gpu.tmpl 149.4 KB
Newer Older
1 2 3 4
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
	"http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []>

5
<book id="gpuDevelopersGuide">
6
  <bookinfo>
7
    <title>Linux GPU Driver Developer's Guide</title>
8

9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
    <authorgroup>
      <author>
	<firstname>Jesse</firstname>
	<surname>Barnes</surname>
	<contrib>Initial version</contrib>
	<affiliation>
	  <orgname>Intel Corporation</orgname>
	  <address>
	    <email>jesse.barnes@intel.com</email>
	  </address>
	</affiliation>
      </author>
      <author>
	<firstname>Laurent</firstname>
	<surname>Pinchart</surname>
	<contrib>Driver internals</contrib>
	<affiliation>
	  <orgname>Ideas on board SPRL</orgname>
	  <address>
	    <email>laurent.pinchart@ideasonboard.com</email>
	  </address>
	</affiliation>
      </author>
D
Daniel Vetter 已提交
32 33 34 35 36 37 38 39 40 41 42
      <author>
	<firstname>Daniel</firstname>
	<surname>Vetter</surname>
	<contrib>Contributions all over the place</contrib>
	<affiliation>
	  <orgname>Intel Corporation</orgname>
	  <address>
	    <email>daniel.vetter@ffwll.ch</email>
	  </address>
	</affiliation>
      </author>
43 44 45 46 47 48 49 50 51 52
      <author>
	<firstname>Lukas</firstname>
	<surname>Wunner</surname>
	<contrib>vga_switcheroo documentation</contrib>
	<affiliation>
	  <address>
	    <email>lukas@wunner.de</email>
	  </address>
	</affiliation>
      </author>
53 54
    </authorgroup>

55 56
    <copyright>
      <year>2008-2009</year>
D
Daniel Vetter 已提交
57
      <year>2013-2014</year>
58
      <holder>Intel Corporation</holder>
D
Daniel Vetter 已提交
59 60 61
    </copyright>
    <copyright>
      <year>2012</year>
62
      <holder>Laurent Pinchart</holder>
63
    </copyright>
64 65 66 67
    <copyright>
      <year>2015</year>
      <holder>Lukas Wunner</holder>
    </copyright>
68 69 70 71 72 73 74 75

    <legalnotice>
      <para>
	The contents of this file may be used under the terms of the GNU
	General Public License version 2 (the "GPL") as distributed in
	the kernel source COPYING file.
      </para>
    </legalnotice>
76 77 78 79 80 81 82 83 84 85

    <revhistory>
      <!-- Put document revisions here, newest first. -->
      <revision>
	<revnumber>1.0</revnumber>
	<date>2012-07-13</date>
	<authorinitials>LP</authorinitials>
	<revremark>Added extensive documentation about driver internals.
	</revremark>
      </revision>
86 87 88 89 90 91 92
      <revision>
	<revnumber>1.1</revnumber>
	<date>2015-10-11</date>
	<authorinitials>LW</authorinitials>
	<revremark>Added vga_switcheroo documentation.
	</revremark>
      </revision>
93
    </revhistory>
94 95 96 97
  </bookinfo>

<toc></toc>

98 99 100 101
<part id="drmCore">
  <title>DRM Core</title>
  <partintro>
    <para>
102 103 104
      This first part of the GPU Driver Developer's Guide documents core DRM
      code, helper libraries for writing drivers and generic userspace
      interfaces exposed by DRM drivers.
105 106
    </para>
  </partintro>
107 108 109 110 111 112 113

  <chapter id="drmIntroduction">
    <title>Introduction</title>
    <para>
      The Linux DRM layer contains code intended to support the needs
      of complex graphics devices, usually containing programmable
      pipelines well suited to 3D graphics acceleration.  Graphics
M
Michael Witten 已提交
114
      drivers in the kernel may make use of DRM functions to make
115 116 117 118 119 120 121 122 123 124 125 126
      tasks like memory management, interrupt handling and DMA easier,
      and provide a uniform interface to applications.
    </para>
    <para>
      A note on versions: this guide covers features found in the DRM
      tree, including the TTM memory manager, output configuration and
      mode setting, and the new vblank internals, in addition to all
      the regular features found in current kernels.
    </para>
    <para>
      [Insert diagram of typical DRM stack here]
    </para>
D
Daniel Vetter 已提交
127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163
  <sect1>
    <title>Style Guidelines</title>
    <para>
      For consistency this documentation uses American English. Abbreviations
      are written as all-uppercase, for example: DRM, KMS, IOCTL, CRTC, and so
      on. To aid in reading, documentations make full use of the markup
      characters kerneldoc provides: @parameter for function parameters, @member
      for structure members, &amp;structure to reference structures and
      function() for functions. These all get automatically hyperlinked if
      kerneldoc for the referenced objects exists. When referencing entries in
      function vtables please use -&gt;vfunc(). Note that kerneldoc does
      not support referencing struct members directly, so please add a reference
      to the vtable struct somewhere in the same paragraph or at least section.
    </para>
    <para>
      Except in special situations (to separate locked from unlocked variants)
      locking requirements for functions aren't documented in the kerneldoc.
      Instead locking should be check at runtime using e.g.
      <code>WARN_ON(!mutex_is_locked(...));</code>. Since it's much easier to
      ignore documentation than runtime noise this provides more value. And on
      top of that runtime checks do need to be updated when the locking rules
      change, increasing the chances that they're correct. Within the
      documentation the locking rules should be explained in the relevant
      structures: Either in the comment for the lock explaining what it
      protects, or data fields need a note about which lock protects them, or
      both.
    </para>
    <para>
      Functions which have a non-<code>void</code> return value should have a
      section called "Returns" explaining the expected return values in
      different cases and their meanings. Currently there's no consensus whether
      that section name should be all upper-case or not, and whether it should
      end in a colon or not. Go with the file-local style. Other common section
      names are "Notes" with information for dangerous or tricky corner cases,
      and "FIXME" where the interface could be cleaned up.
    </para>
  </sect1>
164 165 166 167 168 169 170 171 172 173 174 175
  </chapter>

  <!-- Internals -->

  <chapter id="drmInternals">
    <title>DRM Internals</title>
    <para>
      This chapter documents DRM internals relevant to driver authors
      and developers working to add support for the latest features to
      existing drivers.
    </para>
    <para>
176
      First, we go over some typical driver initialization
177 178
      requirements, like setting up command buffers, creating an
      initial output configuration, and initializing core services.
179
      Subsequent sections cover core internals in more detail,
180 181 182 183 184 185 186 187 188 189 190 191 192 193 194
      providing implementation notes and examples.
    </para>
    <para>
      The DRM layer provides several services to graphics drivers,
      many of them driven by the application interfaces it provides
      through libdrm, the library that wraps most of the DRM ioctls.
      These include vblank event handling, memory
      management, output management, framebuffer management, command
      submission &amp; fencing, suspend/resume support, and DMA
      services.
    </para>

  <!-- Internals: driver init -->

  <sect1>
195 196 197 198
    <title>Driver Initialization</title>
    <para>
      At the core of every DRM driver is a <structname>drm_driver</structname>
      structure. Drivers typically statically initialize a drm_driver structure,
199 200 201 202
      and then pass it to <function>drm_dev_alloc()</function> to allocate a
      device instance. After the device instance is fully initialized it can be
      registered (which makes it accessible from userspace) using
      <function>drm_dev_register()</function>.
203
    </para>
204 205 206 207 208 209 210
    <para>
      The <structname>drm_driver</structname> structure contains static
      information that describes the driver and features it supports, and
      pointers to methods that the DRM core will call to implement the DRM API.
      We will first go through the <structname>drm_driver</structname> static
      information fields, and will then describe individual operations in
      details as they get used in later sections.
211 212
    </para>
    <sect2>
213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263
      <title>Driver Information</title>
      <sect3>
        <title>Driver Features</title>
        <para>
          Drivers inform the DRM core about their requirements and supported
          features by setting appropriate flags in the
          <structfield>driver_features</structfield> field. Since those flags
          influence the DRM core behaviour since registration time, most of them
          must be set to registering the <structname>drm_driver</structname>
          instance.
        </para>
        <synopsis>u32 driver_features;</synopsis>
        <variablelist>
          <title>Driver Feature Flags</title>
          <varlistentry>
            <term>DRIVER_USE_AGP</term>
            <listitem><para>
              Driver uses AGP interface, the DRM core will manage AGP resources.
            </para></listitem>
          </varlistentry>
          <varlistentry>
            <term>DRIVER_REQUIRE_AGP</term>
            <listitem><para>
              Driver needs AGP interface to function. AGP initialization failure
              will become a fatal error.
            </para></listitem>
          </varlistentry>
          <varlistentry>
            <term>DRIVER_PCI_DMA</term>
            <listitem><para>
              Driver is capable of PCI DMA, mapping of PCI DMA buffers to
              userspace will be enabled. Deprecated.
            </para></listitem>
          </varlistentry>
          <varlistentry>
            <term>DRIVER_SG</term>
            <listitem><para>
              Driver can perform scatter/gather DMA, allocation and mapping of
              scatter/gather buffers will be enabled. Deprecated.
            </para></listitem>
          </varlistentry>
          <varlistentry>
            <term>DRIVER_HAVE_DMA</term>
            <listitem><para>
              Driver supports DMA, the userspace DMA API will be supported.
              Deprecated.
            </para></listitem>
          </varlistentry>
          <varlistentry>
            <term>DRIVER_HAVE_IRQ</term><term>DRIVER_IRQ_SHARED</term>
            <listitem><para>
264 265 266 267 268 269
              DRIVER_HAVE_IRQ indicates whether the driver has an IRQ handler
              managed by the DRM Core. The core will support simple IRQ handler
              installation when the flag is set. The installation process is
              described in <xref linkend="drm-irq-registration"/>.</para>
              <para>DRIVER_IRQ_SHARED indicates whether the device &amp; handler
              support shared IRQs (note that this is required of PCI  drivers).
270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289
            </para></listitem>
          </varlistentry>
          <varlistentry>
            <term>DRIVER_GEM</term>
            <listitem><para>
              Driver use the GEM memory manager.
            </para></listitem>
          </varlistentry>
          <varlistentry>
            <term>DRIVER_MODESET</term>
            <listitem><para>
              Driver supports mode setting interfaces (KMS).
            </para></listitem>
          </varlistentry>
          <varlistentry>
            <term>DRIVER_PRIME</term>
            <listitem><para>
              Driver implements DRM PRIME buffer sharing.
            </para></listitem>
          </varlistentry>
290 291 292 293 294 295
          <varlistentry>
            <term>DRIVER_RENDER</term>
            <listitem><para>
              Driver supports dedicated render nodes.
            </para></listitem>
          </varlistentry>
R
Rob Clark 已提交
296 297 298 299 300 301 302 303
          <varlistentry>
            <term>DRIVER_ATOMIC</term>
            <listitem><para>
              Driver supports atomic properties.  In this case the driver
              must implement appropriate obj->atomic_get_property() vfuncs
              for any modeset objects with driver specific properties.
            </para></listitem>
          </varlistentry>
304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351
        </variablelist>
      </sect3>
      <sect3>
        <title>Major, Minor and Patchlevel</title>
        <synopsis>int major;
int minor;
int patchlevel;</synopsis>
        <para>
          The DRM core identifies driver versions by a major, minor and patch
          level triplet. The information is printed to the kernel log at
          initialization time and passed to userspace through the
          DRM_IOCTL_VERSION ioctl.
        </para>
        <para>
          The major and minor numbers are also used to verify the requested driver
          API version passed to DRM_IOCTL_SET_VERSION. When the driver API changes
          between minor versions, applications can call DRM_IOCTL_SET_VERSION to
          select a specific version of the API. If the requested major isn't equal
          to the driver major, or the requested minor is larger than the driver
          minor, the DRM_IOCTL_SET_VERSION call will return an error. Otherwise
          the driver's set_version() method will be called with the requested
          version.
        </para>
      </sect3>
      <sect3>
        <title>Name, Description and Date</title>
        <synopsis>char *name;
char *desc;
char *date;</synopsis>
        <para>
          The driver name is printed to the kernel log at initialization time,
          used for IRQ registration and passed to userspace through
          DRM_IOCTL_VERSION.
        </para>
        <para>
          The driver description is a purely informative string passed to
          userspace through the DRM_IOCTL_VERSION ioctl and otherwise unused by
          the kernel.
        </para>
        <para>
          The driver date, formatted as YYYYMMDD, is meant to identify the date of
          the latest modification to the driver. However, as most drivers fail to
          update it, its value is mostly useless. The DRM core prints it to the
          kernel log at initialization time and passes it to userspace through the
          DRM_IOCTL_VERSION ioctl.
        </para>
      </sect3>
    </sect2>
352
    <sect2>
353 354
      <title>Device Instance and Driver Handling</title>
!Pdrivers/gpu/drm/drm_drv.c driver instance overview
355
!Edrivers/gpu/drm/drm_drv.c
356
    </sect2>
357 358 359 360 361 362 363 364
    <sect2>
      <title>Driver Load</title>
      <sect3 id="drm-irq-registration">
        <title>IRQ Registration</title>
        <para>
          The DRM core tries to facilitate IRQ handler registration and
          unregistration by providing <function>drm_irq_install</function> and
          <function>drm_irq_uninstall</function> functions. Those functions only
365 366
          support a single interrupt per device, devices that use more than one
          IRQs need to be handled manually.
367
        </para>
368 369 370 371 372 373 374 375 376
        <sect4>
          <title>Managed IRQ Registration</title>
          <para>
            <function>drm_irq_install</function> starts by calling the
            <methodname>irq_preinstall</methodname> driver operation. The operation
            is optional and must make sure that the interrupt will not get fired by
            clearing all pending interrupt flags or disabling the interrupt.
          </para>
          <para>
377
            The passed-in IRQ will then be requested by a call to
378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421
            <function>request_irq</function>. If the DRIVER_IRQ_SHARED driver
            feature flag is set, a shared (IRQF_SHARED) IRQ handler will be
            requested.
          </para>
          <para>
            The IRQ handler function must be provided as the mandatory irq_handler
            driver operation. It will get passed directly to
            <function>request_irq</function> and thus has the same prototype as all
            IRQ handlers. It will get called with a pointer to the DRM device as the
            second argument.
          </para>
          <para>
            Finally the function calls the optional
            <methodname>irq_postinstall</methodname> driver operation. The operation
            usually enables interrupts (excluding the vblank interrupt, which is
            enabled separately), but drivers may choose to enable/disable interrupts
            at a different time.
          </para>
          <para>
            <function>drm_irq_uninstall</function> is similarly used to uninstall an
            IRQ handler. It starts by waking up all processes waiting on a vblank
            interrupt to make sure they don't hang, and then calls the optional
            <methodname>irq_uninstall</methodname> driver operation. The operation
            must disable all hardware interrupts. Finally the function frees the IRQ
            by calling <function>free_irq</function>.
          </para>
        </sect4>
        <sect4>
          <title>Manual IRQ Registration</title>
          <para>
            Drivers that require multiple interrupt handlers can't use the managed
            IRQ registration functions. In that case IRQs must be registered and
            unregistered manually (usually with the <function>request_irq</function>
            and <function>free_irq</function> functions, or their devm_* equivalent).
          </para>
          <para>
            When manually registering IRQs, drivers must not set the DRIVER_HAVE_IRQ
            driver feature flag, and must not provide the
	    <methodname>irq_handler</methodname> driver operation. They must set the
	    <structname>drm_device</structname> <structfield>irq_enabled</structfield>
	    field to 1 upon registration of the IRQs, and clear it to 0 after
	    unregistering the IRQs.
          </para>
        </sect4>
422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449
      </sect3>
      <sect3>
        <title>Memory Manager Initialization</title>
        <para>
          Every DRM driver requires a memory manager which must be initialized at
          load time. DRM currently contains two memory managers, the Translation
          Table Manager (TTM) and the Graphics Execution Manager (GEM).
          This document describes the use of the GEM memory manager only. See
          <xref linkend="drm-memory-management"/> for details.
        </para>
      </sect3>
      <sect3>
        <title>Miscellaneous Device Configuration</title>
        <para>
          Another task that may be necessary for PCI devices during configuration
          is mapping the video BIOS. On many devices, the VBIOS describes device
          configuration, LCD panel timings (if any), and contains flags indicating
          device state. Mapping the BIOS can be done using the pci_map_rom() call,
          a convenience function that takes care of mapping the actual ROM,
          whether it has been shadowed into memory (typically at address 0xc0000)
          or exists on the PCI device in the ROM BAR. Note that after the ROM has
          been mapped and any necessary information has been extracted, it should
          be unmapped; on many devices, the ROM address decoder is shared with
          other BARs, so leaving it mapped could cause undesired behaviour like
          hangs or memory corruption.
  <!--!Fdrivers/pci/rom.c pci_map_rom-->
        </para>
      </sect3>
450
    </sect2>
451 452 453 454 455 456 457 458 459 460 461 462
    <sect2>
      <title>Bus-specific Device Registration and PCI Support</title>
      <para>
        A number of functions are provided to help with device registration.
	The functions deal with PCI and platform devices respectively and are
	only provided for historical reasons. These are all deprecated and
	shouldn't be used in new drivers. Besides that there's a few
	helpers for pci drivers.
      </para>
!Edrivers/gpu/drm/drm_pci.c
!Edrivers/gpu/drm/drm_platform.c
    </sect2>
463
  </sect1>
464

465
  <!-- Internals: memory management -->
466

467 468 469 470 471 472 473 474 475 476 477 478 479
  <sect1 id="drm-memory-management">
    <title>Memory management</title>
    <para>
      Modern Linux systems require large amount of graphics memory to store
      frame buffers, textures, vertices and other graphics-related data. Given
      the very dynamic nature of many of that data, managing graphics memory
      efficiently is thus crucial for the graphics stack and plays a central
      role in the DRM infrastructure.
    </para>
    <para>
      The DRM core includes two memory managers, namely Translation Table Maps
      (TTM) and Graphics Execution Manager (GEM). TTM was the first DRM memory
      manager to be developed and tried to be a one-size-fits-them all
480
      solution. It provides a single userspace API to accommodate the need of
481 482 483 484 485 486 487 488 489 490 491
      all hardware, supporting both Unified Memory Architecture (UMA) devices
      and devices with dedicated video RAM (i.e. most discrete video cards).
      This resulted in a large, complex piece of code that turned out to be
      hard to use for driver development.
    </para>
    <para>
      GEM started as an Intel-sponsored project in reaction to TTM's
      complexity. Its design philosophy is completely different: instead of
      providing a solution to every graphics memory-related problems, GEM
      identified common code between drivers and created a support library to
      share it. GEM has simpler initialization and execution requirements than
492
      TTM, but has no video RAM management capabilities and is thus limited to
493 494
      UMA devices.
    </para>
495
    <sect2>
496
      <title>The Translation Table Manager (TTM)</title>
497
      <para>
T
Thierry Reding 已提交
498
        TTM design background and information belongs here.
499 500
      </para>
      <sect3>
T
Thierry Reding 已提交
501
        <title>TTM initialization</title>
502 503 504 505 506 507 508
        <warning><para>This section is outdated.</para></warning>
        <para>
          Drivers wishing to support TTM must fill out a drm_bo_driver
          structure. The structure contains several fields with function
          pointers for initializing the TTM, allocating and freeing memory,
          waiting for command completion and fence synchronization, and memory
          migration. See the radeon_ttm.c file for an example of usage.
T
Thierry Reding 已提交
509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544
        </para>
        <para>
          The ttm_global_reference structure is made up of several fields:
        </para>
        <programlisting>
          struct ttm_global_reference {
                  enum ttm_global_types global_type;
                  size_t size;
                  void *object;
                  int (*init) (struct ttm_global_reference *);
                  void (*release) (struct ttm_global_reference *);
          };
        </programlisting>
        <para>
          There should be one global reference structure for your memory
          manager as a whole, and there will be others for each object
          created by the memory manager at runtime.  Your global TTM should
          have a type of TTM_GLOBAL_TTM_MEM.  The size field for the global
          object should be sizeof(struct ttm_mem_global), and the init and
          release hooks should point at your driver-specific init and
          release routines, which probably eventually call
          ttm_mem_global_init and ttm_mem_global_release, respectively.
        </para>
        <para>
          Once your global TTM accounting structure is set up and initialized
          by calling ttm_global_item_ref() on it,
          you need to create a buffer object TTM to
          provide a pool for buffer object allocation by clients and the
          kernel itself.  The type of this object should be TTM_GLOBAL_TTM_BO,
          and its size should be sizeof(struct ttm_bo_global).  Again,
          driver-specific init and release functions may be provided,
          likely eventually calling ttm_bo_global_init() and
          ttm_bo_global_release(), respectively.  Also, like the previous
          object, ttm_global_item_ref() is used to create an initial reference
          count for the TTM, which will call your initialization function.
        </para>
545
      </sect3>
546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571
    </sect2>
    <sect2 id="drm-gem">
      <title>The Graphics Execution Manager (GEM)</title>
      <para>
        The GEM design approach has resulted in a memory manager that doesn't
        provide full coverage of all (or even all common) use cases in its
        userspace or kernel API. GEM exposes a set of standard memory-related
        operations to userspace and a set of helper functions to drivers, and let
        drivers implement hardware-specific operations with their own private API.
      </para>
      <para>
        The GEM userspace API is described in the
        <ulink url="http://lwn.net/Articles/283798/"><citetitle>GEM - the Graphics
        Execution Manager</citetitle></ulink> article on LWN. While slightly
        outdated, the document provides a good overview of the GEM API principles.
        Buffer allocation and read and write operations, described as part of the
        common GEM API, are currently implemented using driver-specific ioctls.
      </para>
      <para>
        GEM is data-agnostic. It manages abstract buffer objects without knowing
        what individual buffers contain. APIs that require knowledge of buffer
        contents or purpose, such as buffer allocation or synchronization
        primitives, are thus outside of the scope of GEM and must be implemented
        using driver-specific ioctls.
      </para>
      <para>
T
Thierry Reding 已提交
572 573 574 575 576 577 578
        On a fundamental level, GEM involves several operations:
        <itemizedlist>
          <listitem>Memory allocation and freeing</listitem>
          <listitem>Command execution</listitem>
          <listitem>Aperture management at command execution time</listitem>
        </itemizedlist>
        Buffer object allocation is relatively straightforward and largely
579 580 581 582 583
        provided by Linux's shmem layer, which provides memory to back each
        object.
      </para>
      <para>
        Device-specific operations, such as command execution, pinning, buffer
T
Thierry Reding 已提交
584
        read &amp; write, mapping, and domain ownership transfers are left to
585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607
        driver-specific ioctls.
      </para>
      <sect3>
        <title>GEM Initialization</title>
        <para>
          Drivers that use GEM must set the DRIVER_GEM bit in the struct
          <structname>drm_driver</structname>
          <structfield>driver_features</structfield> field. The DRM core will
          then automatically initialize the GEM core before calling the
          <methodname>load</methodname> operation. Behind the scene, this will
          create a DRM Memory Manager object which provides an address space
          pool for object allocation.
        </para>
        <para>
          In a KMS configuration, drivers need to allocate and initialize a
          command ring buffer following core GEM initialization if required by
          the hardware. UMA devices usually have what is called a "stolen"
          memory region, which provides space for the initial framebuffer and
          large, contiguous memory regions required by the device. This space is
          typically not managed by GEM, and must be initialized separately into
          its own DRM MM object.
        </para>
      </sect3>
608
      <sect3>
609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662
        <title>GEM Objects Creation</title>
        <para>
          GEM splits creation of GEM objects and allocation of the memory that
          backs them in two distinct operations.
        </para>
        <para>
          GEM objects are represented by an instance of struct
          <structname>drm_gem_object</structname>. Drivers usually need to extend
          GEM objects with private information and thus create a driver-specific
          GEM object structure type that embeds an instance of struct
          <structname>drm_gem_object</structname>.
        </para>
        <para>
          To create a GEM object, a driver allocates memory for an instance of its
          specific GEM object type and initializes the embedded struct
          <structname>drm_gem_object</structname> with a call to
          <function>drm_gem_object_init</function>. The function takes a pointer to
          the DRM device, a pointer to the GEM object and the buffer object size
          in bytes.
        </para>
        <para>
          GEM uses shmem to allocate anonymous pageable memory.
          <function>drm_gem_object_init</function> will create an shmfs file of
          the requested size and store it into the struct
          <structname>drm_gem_object</structname> <structfield>filp</structfield>
          field. The memory is used as either main storage for the object when the
          graphics hardware uses system memory directly or as a backing store
          otherwise.
        </para>
        <para>
          Drivers are responsible for the actual physical pages allocation by
          calling <function>shmem_read_mapping_page_gfp</function> for each page.
          Note that they can decide to allocate pages when initializing the GEM
          object, or to delay allocation until the memory is needed (for instance
          when a page fault occurs as a result of a userspace memory access or
          when the driver needs to start a DMA transfer involving the memory).
        </para>
        <para>
          Anonymous pageable memory allocation is not always desired, for instance
          when the hardware requires physically contiguous system memory as is
          often the case in embedded devices. Drivers can create GEM objects with
          no shmfs backing (called private GEM objects) by initializing them with
          a call to <function>drm_gem_private_object_init</function> instead of
          <function>drm_gem_object_init</function>. Storage for private GEM
          objects must be managed by drivers.
        </para>
      </sect3>
      <sect3>
        <title>GEM Objects Lifetime</title>
        <para>
          All GEM objects are reference-counted by the GEM core. References can be
          acquired and release by <function>calling drm_gem_object_reference</function>
          and <function>drm_gem_object_unreference</function> respectively. The
          caller must hold the <structname>drm_device</structname>
D
Daniel Vetter 已提交
663 664 665 666
	  <structfield>struct_mutex</structfield> lock when calling
	  <function>drm_gem_object_reference</function>. As a convenience, GEM
	  provides <function>drm_gem_object_unreference_unlocked</function>
	  functions that can be called without holding the lock.
667 668 669 670 671 672 673 674 675 676
        </para>
        <para>
          When the last reference to a GEM object is released the GEM core calls
          the <structname>drm_driver</structname>
          <methodname>gem_free_object</methodname> operation. That operation is
          mandatory for GEM-enabled drivers and must free the GEM object and all
          associated resources.
        </para>
        <para>
          <synopsis>void (*gem_free_object) (struct drm_gem_object *obj);</synopsis>
D
Daniel Vetter 已提交
677 678 679
          Drivers are responsible for freeing all GEM object resources. This includes
          the resources created by the GEM core, which need to be released with
          <function>drm_gem_object_release</function>.
680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725
        </para>
      </sect3>
      <sect3>
        <title>GEM Objects Naming</title>
        <para>
          Communication between userspace and the kernel refers to GEM objects
          using local handles, global names or, more recently, file descriptors.
          All of those are 32-bit integer values; the usual Linux kernel limits
          apply to the file descriptors.
        </para>
        <para>
          GEM handles are local to a DRM file. Applications get a handle to a GEM
          object through a driver-specific ioctl, and can use that handle to refer
          to the GEM object in other standard or driver-specific ioctls. Closing a
          DRM file handle frees all its GEM handles and dereferences the
          associated GEM objects.
        </para>
        <para>
          To create a handle for a GEM object drivers call
          <function>drm_gem_handle_create</function>. The function takes a pointer
          to the DRM file and the GEM object and returns a locally unique handle.
          When the handle is no longer needed drivers delete it with a call to
          <function>drm_gem_handle_delete</function>. Finally the GEM object
          associated with a handle can be retrieved by a call to
          <function>drm_gem_object_lookup</function>.
        </para>
        <para>
          Handles don't take ownership of GEM objects, they only take a reference
          to the object that will be dropped when the handle is destroyed. To
          avoid leaking GEM objects, drivers must make sure they drop the
          reference(s) they own (such as the initial reference taken at object
          creation time) as appropriate, without any special consideration for the
          handle. For example, in the particular case of combined GEM object and
          handle creation in the implementation of the
          <methodname>dumb_create</methodname> operation, drivers must drop the
          initial reference to the GEM object before returning the handle.
        </para>
        <para>
          GEM names are similar in purpose to handles but are not local to DRM
          files. They can be passed between processes to reference a GEM object
          globally. Names can't be used directly to refer to objects in the DRM
          API, applications must convert handles to names and names to handles
          using the DRM_IOCTL_GEM_FLINK and DRM_IOCTL_GEM_OPEN ioctls
          respectively. The conversion is handled by the DRM core without any
          driver-specific support.
        </para>
T
Thierry Reding 已提交
726 727 728 729 730 731 732 733 734 735
        <para>
          GEM also supports buffer sharing with dma-buf file descriptors through
          PRIME. GEM-based drivers must use the provided helpers functions to
          implement the exporting and importing correctly. See <xref linkend="drm-prime-support" />.
          Since sharing file descriptors is inherently more secure than the
          easily guessable and global GEM names it is the preferred buffer
          sharing mechanism. Sharing buffers through GEM names is only supported
          for legacy userspace. Furthermore PRIME also allows cross-device
          buffer sharing since it is based on dma-bufs.
        </para>
736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761
      </sect3>
      <sect3 id="drm-gem-objects-mapping">
        <title>GEM Objects Mapping</title>
        <para>
          Because mapping operations are fairly heavyweight GEM favours
          read/write-like access to buffers, implemented through driver-specific
          ioctls, over mapping buffers to userspace. However, when random access
          to the buffer is needed (to perform software rendering for instance),
          direct access to the object can be more efficient.
        </para>
        <para>
          The mmap system call can't be used directly to map GEM objects, as they
          don't have their own file handle. Two alternative methods currently
          co-exist to map GEM objects to userspace. The first method uses a
          driver-specific ioctl to perform the mapping operation, calling
          <function>do_mmap</function> under the hood. This is often considered
          dubious, seems to be discouraged for new GEM-enabled drivers, and will
          thus not be described here.
        </para>
        <para>
          The second method uses the mmap system call on the DRM file handle.
          <synopsis>void *mmap(void *addr, size_t length, int prot, int flags, int fd,
             off_t offset);</synopsis>
          DRM identifies the GEM object to be mapped by a fake offset passed
          through the mmap offset argument. Prior to being mapped, a GEM object
          must thus be associated with a fake offset. To do so, drivers must call
D
Daniel Vetter 已提交
762
          <function>drm_gem_create_mmap_offset</function> on the object.
763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832
        </para>
        <para>
          Once allocated, the fake offset value
          must be passed to the application in a driver-specific way and can then
          be used as the mmap offset argument.
        </para>
        <para>
          The GEM core provides a helper method <function>drm_gem_mmap</function>
          to handle object mapping. The method can be set directly as the mmap
          file operation handler. It will look up the GEM object based on the
          offset value and set the VMA operations to the
          <structname>drm_driver</structname> <structfield>gem_vm_ops</structfield>
          field. Note that <function>drm_gem_mmap</function> doesn't map memory to
          userspace, but relies on the driver-provided fault handler to map pages
          individually.
        </para>
        <para>
          To use <function>drm_gem_mmap</function>, drivers must fill the struct
          <structname>drm_driver</structname> <structfield>gem_vm_ops</structfield>
          field with a pointer to VM operations.
        </para>
        <para>
          <synopsis>struct vm_operations_struct *gem_vm_ops

  struct vm_operations_struct {
          void (*open)(struct vm_area_struct * area);
          void (*close)(struct vm_area_struct * area);
          int (*fault)(struct vm_area_struct *vma, struct vm_fault *vmf);
  };</synopsis>
        </para>
        <para>
          The <methodname>open</methodname> and <methodname>close</methodname>
          operations must update the GEM object reference count. Drivers can use
          the <function>drm_gem_vm_open</function> and
          <function>drm_gem_vm_close</function> helper functions directly as open
          and close handlers.
        </para>
        <para>
          The fault operation handler is responsible for mapping individual pages
          to userspace when a page fault occurs. Depending on the memory
          allocation scheme, drivers can allocate pages at fault time, or can
          decide to allocate memory for the GEM object at the time the object is
          created.
        </para>
        <para>
          Drivers that want to map the GEM object upfront instead of handling page
          faults can implement their own mmap file operation handler.
        </para>
      </sect3>
      <sect3>
        <title>Memory Coherency</title>
        <para>
          When mapped to the device or used in a command buffer, backing pages
          for an object are flushed to memory and marked write combined so as to
          be coherent with the GPU. Likewise, if the CPU accesses an object
          after the GPU has finished rendering to the object, then the object
          must be made coherent with the CPU's view of memory, usually involving
          GPU cache flushing of various kinds. This core CPU&lt;-&gt;GPU
          coherency management is provided by a device-specific ioctl, which
          evaluates an object's current domain and performs any necessary
          flushing or synchronization to put the object into the desired
          coherency domain (note that the object may be busy, i.e. an active
          render target; in that case, setting the domain blocks the client and
          waits for rendering to complete before performing any necessary
          flushing operations).
        </para>
      </sect3>
      <sect3>
        <title>Command Execution</title>
        <para>
T
Thierry Reding 已提交
833
          Perhaps the most important GEM function for GPU devices is providing a
834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849
          command execution interface to clients. Client programs construct
          command buffers containing references to previously allocated memory
          objects, and then submit them to GEM. At that point, GEM takes care to
          bind all the objects into the GTT, execute the buffer, and provide
          necessary synchronization between clients accessing the same buffers.
          This often involves evicting some objects from the GTT and re-binding
          others (a fairly expensive operation), and providing relocation
          support which hides fixed GTT offsets from clients. Clients must take
          care not to submit command buffers that reference more objects than
          can fit in the GTT; otherwise, GEM will reject them and no rendering
          will occur. Similarly, if several objects in the buffer require fence
          registers to be allocated for correct rendering (e.g. 2D blits on
          pre-965 chips), care must be taken not to require more fence registers
          than are available to the client. Such resource management should be
          abstracted from the client in libdrm.
        </para>
850
      </sect3>
D
Daniel Vetter 已提交
851 852 853
    </sect2>
    <sect2>
      <title>GEM Function Reference</title>
854
!Edrivers/gpu/drm/drm_gem.c
D
Daniel Vetter 已提交
855
!Iinclude/drm/drm_gem.h
T
Thierry Reding 已提交
856 857 858
    </sect2>
    <sect2>
      <title>VMA Offset Manager</title>
859 860 861
!Pdrivers/gpu/drm/drm_vma_manager.c vma offset manager
!Edrivers/gpu/drm/drm_vma_manager.c
!Iinclude/drm/drm_vma_manager.h
T
Thierry Reding 已提交
862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890
    </sect2>
    <sect2 id="drm-prime-support">
      <title>PRIME Buffer Sharing</title>
      <para>
        PRIME is the cross device buffer sharing framework in drm, originally
        created for the OPTIMUS range of multi-gpu platforms. To userspace
        PRIME buffers are dma-buf based file descriptors.
      </para>
      <sect3>
        <title>Overview and Driver Interface</title>
        <para>
          Similar to GEM global names, PRIME file descriptors are
          also used to share buffer objects across processes. They offer
          additional security: as file descriptors must be explicitly sent over
          UNIX domain sockets to be shared between applications, they can't be
          guessed like the globally unique GEM names.
        </para>
        <para>
          Drivers that support the PRIME
          API must set the DRIVER_PRIME bit in the struct
          <structname>drm_driver</structname>
          <structfield>driver_features</structfield> field, and implement the
          <methodname>prime_handle_to_fd</methodname> and
          <methodname>prime_fd_to_handle</methodname> operations.
        </para>
        <para>
          <synopsis>int (*prime_handle_to_fd)(struct drm_device *dev,
                          struct drm_file *file_priv, uint32_t handle,
                          uint32_t flags, int *prime_fd);
891
int (*prime_fd_to_handle)(struct drm_device *dev,
T
Thierry Reding 已提交
892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913
                          struct drm_file *file_priv, int prime_fd,
                          uint32_t *handle);</synopsis>
            Those two operations convert a handle to a PRIME file descriptor and
            vice versa. Drivers must use the kernel dma-buf buffer sharing framework
            to manage the PRIME file descriptors. Similar to the mode setting
            API PRIME is agnostic to the underlying buffer object manager, as
            long as handles are 32bit unsigned integers.
          </para>
          <para>
            While non-GEM drivers must implement the operations themselves, GEM
            drivers must use the <function>drm_gem_prime_handle_to_fd</function>
            and <function>drm_gem_prime_fd_to_handle</function> helper functions.
            Those helpers rely on the driver
            <methodname>gem_prime_export</methodname> and
            <methodname>gem_prime_import</methodname> operations to create a dma-buf
            instance from a GEM object (dma-buf exporter role) and to create a GEM
            object from a dma-buf instance (dma-buf importer role).
          </para>
          <para>
            <synopsis>struct dma_buf * (*gem_prime_export)(struct drm_device *dev,
                             struct drm_gem_object *obj,
                             int flags);
914
struct drm_gem_object * (*gem_prime_import)(struct drm_device *dev,
T
Thierry Reding 已提交
915 916 917 918
                                            struct dma_buf *dma_buf);</synopsis>
            These two operations are mandatory for GEM drivers that support
            PRIME.
          </para>
919
        </sect3>
T
Thierry Reding 已提交
920 921 922 923 924 925 926
      <sect3>
        <title>PRIME Helper Functions</title>
!Pdrivers/gpu/drm/drm_prime.c PRIME Helpers
      </sect3>
    </sect2>
    <sect2>
      <title>PRIME Function References</title>
927
!Edrivers/gpu/drm/drm_prime.c
T
Thierry Reding 已提交
928 929 930 931 932
    </sect2>
    <sect2>
      <title>DRM MM Range Allocator</title>
      <sect3>
        <title>Overview</title>
933
!Pdrivers/gpu/drm/drm_mm.c Overview
T
Thierry Reding 已提交
934 935 936
      </sect3>
      <sect3>
        <title>LRU Scan/Eviction Support</title>
937
!Pdrivers/gpu/drm/drm_mm.c lru scan roaster
T
Thierry Reding 已提交
938
      </sect3>
939
      </sect2>
T
Thierry Reding 已提交
940 941
    <sect2>
      <title>DRM MM Range Allocator Function References</title>
942 943
!Edrivers/gpu/drm/drm_mm.c
!Iinclude/drm/drm_mm.h
T
Thierry Reding 已提交
944
    </sect2>
945 946 947 948 949 950
    <sect2>
      <title>CMA Helper Functions Reference</title>
!Pdrivers/gpu/drm/drm_gem_cma_helper.c cma helpers
!Edrivers/gpu/drm/drm_gem_cma_helper.c
!Iinclude/drm/drm_gem_cma_helper.h
    </sect2>
951 952 953
  </sect1>

  <!-- Internals: mode setting -->
954

955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977
  <sect1 id="drm-mode-setting">
    <title>Mode Setting</title>
    <para>
      Drivers must initialize the mode setting core by calling
      <function>drm_mode_config_init</function> on the DRM device. The function
      initializes the <structname>drm_device</structname>
      <structfield>mode_config</structfield> field and never fails. Once done,
      mode configuration must be setup by initializing the following fields.
    </para>
    <itemizedlist>
      <listitem>
        <synopsis>int min_width, min_height;
int max_width, max_height;</synopsis>
        <para>
	  Minimum and maximum width and height of the frame buffers in pixel
	  units.
	</para>
      </listitem>
      <listitem>
        <synopsis>struct drm_mode_config_funcs *funcs;</synopsis>
	<para>Mode setting functions.</para>
      </listitem>
    </itemizedlist>
978 979
    <sect2>
      <title>Display Modes Function Reference</title>
980
!Iinclude/drm/drm_modes.h
981
!Edrivers/gpu/drm/drm_modes.c
D
Daniel Vetter 已提交
982 983 984 985
    </sect2>
    <sect2>
      <title>Atomic Mode Setting Function Reference</title>
!Edrivers/gpu/drm/drm_atomic.c
986
!Idrivers/gpu/drm/drm_atomic.c
987
    </sect2>
988
    <sect2>
989 990 991 992
      <title>Frame Buffer Creation</title>
      <synopsis>struct drm_framebuffer *(*fb_create)(struct drm_device *dev,
				     struct drm_file *file_priv,
				     struct drm_mode_fb_cmd2 *mode_cmd);</synopsis>
993
      <para>
994 995 996 997 998 999 1000 1001 1002 1003
        Frame buffers are abstract memory objects that provide a source of
        pixels to scanout to a CRTC. Applications explicitly request the
        creation of frame buffers through the DRM_IOCTL_MODE_ADDFB(2) ioctls and
        receive an opaque handle that can be passed to the KMS CRTC control,
        plane configuration and page flip functions.
      </para>
      <para>
        Frame buffers rely on the underneath memory manager for low-level memory
        operations. When creating a frame buffer applications pass a memory
        handle (or a list of memory handles for multi-planar formats) through
1004 1005 1006 1007 1008
	the <parameter>drm_mode_fb_cmd2</parameter> argument. For drivers using
	GEM as their userspace buffer management interface this would be a GEM
	handle.  Drivers are however free to use their own backing storage object
	handles, e.g. vmwgfx directly exposes special TTM handles to userspace
	and so expects TTM handles in the create ioctl and not GEM handles.
1009 1010 1011 1012 1013 1014 1015 1016 1017 1018
      </para>
      <para>
        Drivers must first validate the requested frame buffer parameters passed
        through the mode_cmd argument. In particular this is where invalid
        sizes, pixel formats or pitches can be caught.
      </para>
      <para>
        If the parameters are deemed valid, drivers then create, initialize and
        return an instance of struct <structname>drm_framebuffer</structname>.
        If desired the instance can be embedded in a larger driver-specific
1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029
	structure. Drivers must fill its <structfield>width</structfield>,
	<structfield>height</structfield>, <structfield>pitches</structfield>,
        <structfield>offsets</structfield>, <structfield>depth</structfield>,
        <structfield>bits_per_pixel</structfield> and
        <structfield>pixel_format</structfield> fields from the values passed
        through the <parameter>drm_mode_fb_cmd2</parameter> argument. They
        should call the <function>drm_helper_mode_fill_fb_struct</function>
        helper function to do so.
      </para>

      <para>
1030
	The initialization of the new framebuffer instance is finalized with a
1031 1032 1033 1034 1035 1036 1037
	call to <function>drm_framebuffer_init</function> which takes a pointer
	to DRM frame buffer operations (struct
	<structname>drm_framebuffer_funcs</structname>). Note that this function
	publishes the framebuffer and so from this point on it can be accessed
	concurrently from other threads. Hence it must be the last step in the
	driver's framebuffer initialization sequence. Frame buffer operations
	are
1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077
        <itemizedlist>
          <listitem>
            <synopsis>int (*create_handle)(struct drm_framebuffer *fb,
		     struct drm_file *file_priv, unsigned int *handle);</synopsis>
            <para>
              Create a handle to the frame buffer underlying memory object. If
              the frame buffer uses a multi-plane format, the handle will
              reference the memory object associated with the first plane.
            </para>
            <para>
              Drivers call <function>drm_gem_handle_create</function> to create
              the handle.
            </para>
          </listitem>
          <listitem>
            <synopsis>void (*destroy)(struct drm_framebuffer *framebuffer);</synopsis>
            <para>
              Destroy the frame buffer object and frees all associated
              resources. Drivers must call
              <function>drm_framebuffer_cleanup</function> to free resources
              allocated by the DRM core for the frame buffer object, and must
              make sure to unreference all memory objects associated with the
              frame buffer. Handles created by the
              <methodname>create_handle</methodname> operation are released by
              the DRM core.
            </para>
          </listitem>
          <listitem>
            <synopsis>int (*dirty)(struct drm_framebuffer *framebuffer,
	     struct drm_file *file_priv, unsigned flags, unsigned color,
	     struct drm_clip_rect *clips, unsigned num_clips);</synopsis>
            <para>
              This optional operation notifies the driver that a region of the
              frame buffer has changed in response to a DRM_IOCTL_MODE_DIRTYFB
              ioctl call.
            </para>
          </listitem>
        </itemizedlist>
      </para>
      <para>
1078 1079
	The lifetime of a drm framebuffer is controlled with a reference count,
	drivers can grab additional references with
D
Daniel Vetter 已提交
1080
	<function>drm_framebuffer_reference</function>and drop them
1081 1082 1083 1084 1085 1086 1087
	again with <function>drm_framebuffer_unreference</function>. For
	driver-private framebuffers for which the last reference is never
	dropped (e.g. for the fbdev framebuffer when the struct
	<structname>drm_framebuffer</structname> is embedded into the fbdev
	helper struct) drivers can manually clean up a framebuffer at module
	unload time with
	<function>drm_framebuffer_unregister_private</function>.
D
Daniel Vetter 已提交
1088
      </para>
1089
    </sect2>
1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154
    <sect2>
      <title>Dumb Buffer Objects</title>
      <para>
	The KMS API doesn't standardize backing storage object creation and
	leaves it to driver-specific ioctls. Furthermore actually creating a
	buffer object even for GEM-based drivers is done through a
	driver-specific ioctl - GEM only has a common userspace interface for
	sharing and destroying objects. While not an issue for full-fledged
	graphics stacks that include device-specific userspace components (in
	libdrm for instance), this limit makes DRM-based early boot graphics
	unnecessarily complex.
      </para>
      <para>
        Dumb objects partly alleviate the problem by providing a standard
        API to create dumb buffers suitable for scanout, which can then be used
        to create KMS frame buffers.
      </para>
      <para>
        To support dumb objects drivers must implement the
        <methodname>dumb_create</methodname>,
        <methodname>dumb_destroy</methodname> and
        <methodname>dumb_map_offset</methodname> operations.
      </para>
      <itemizedlist>
        <listitem>
          <synopsis>int (*dumb_create)(struct drm_file *file_priv, struct drm_device *dev,
                   struct drm_mode_create_dumb *args);</synopsis>
          <para>
            The <methodname>dumb_create</methodname> operation creates a driver
	    object (GEM or TTM handle) suitable for scanout based on the
	    width, height and depth from the struct
	    <structname>drm_mode_create_dumb</structname> argument. It fills the
	    argument's <structfield>handle</structfield>,
	    <structfield>pitch</structfield> and <structfield>size</structfield>
	    fields with a handle for the newly created object and its line
            pitch and size in bytes.
          </para>
        </listitem>
        <listitem>
          <synopsis>int (*dumb_destroy)(struct drm_file *file_priv, struct drm_device *dev,
                    uint32_t handle);</synopsis>
          <para>
            The <methodname>dumb_destroy</methodname> operation destroys a dumb
            object created by <methodname>dumb_create</methodname>.
          </para>
        </listitem>
        <listitem>
          <synopsis>int (*dumb_map_offset)(struct drm_file *file_priv, struct drm_device *dev,
                       uint32_t handle, uint64_t *offset);</synopsis>
          <para>
            The <methodname>dumb_map_offset</methodname> operation associates an
            mmap fake offset with the object given by the handle and returns
            it. Drivers must use the
            <function>drm_gem_create_mmap_offset</function> function to
            associate the fake offset as described in
            <xref linkend="drm-gem-objects-mapping"/>.
          </para>
        </listitem>
      </itemizedlist>
      <para>
        Note that dumb objects may not be used for gpu acceleration, as has been
	attempted on some ARM embedded platforms. Such drivers really must have
	a hardware-specific ioctl to allocate suitable buffer objects.
      </para>
    </sect2>
1155 1156 1157 1158 1159 1160 1161 1162 1163 1164
    <sect2>
      <title>Output Polling</title>
      <synopsis>void (*output_poll_changed)(struct drm_device *dev);</synopsis>
      <para>
        This operation notifies the driver that the status of one or more
        connectors has changed. Drivers that use the fb helper can just call the
        <function>drm_fb_helper_hotplug_event</function> function to handle this
        operation.
      </para>
    </sect2>
1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180
    <sect2>
      <title>Locking</title>
      <para>
        Beside some lookup structures with their own locking (which is hidden
	behind the interface functions) most of the modeset state is protected
	by the <code>dev-&lt;mode_config.lock</code> mutex and additionally
	per-crtc locks to allow cursor updates, pageflips and similar operations
	to occur concurrently with background tasks like output detection.
	Operations which cross domains like a full modeset always grab all
	locks. Drivers there need to protect resources shared between crtcs with
	additional locking. They also need to be careful to always grab the
	relevant crtc locks if a modset functions touches crtc state, e.g. for
	load detection (which does only grab the <code>mode_config.lock</code>
	to allow concurrent screen updates on live crtcs).
      </para>
    </sect2>
1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202
  </sect1>

  <!-- Internals: kms initialization and cleanup -->

  <sect1 id="drm-kms-init">
    <title>KMS Initialization and Cleanup</title>
    <para>
      A KMS device is abstracted and exposed as a set of planes, CRTCs, encoders
      and connectors. KMS drivers must thus create and initialize all those
      objects at load time after initializing mode setting.
    </para>
    <sect2>
      <title>CRTCs (struct <structname>drm_crtc</structname>)</title>
      <para>
        A CRTC is an abstraction representing a part of the chip that contains a
	pointer to a scanout buffer. Therefore, the number of CRTCs available
	determines how many independent scanout buffers can be active at any
	given time. The CRTC structure contains several fields to support this:
	a pointer to some video memory (abstracted as a frame buffer object), a
	display mode, and an (x, y) offset into the video memory to support
	panning or configurations where one piece of video memory spans multiple
	CRTCs.
1203 1204
      </para>
      <sect3>
1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223
        <title>CRTC Initialization</title>
        <para>
          A KMS device must create and register at least one struct
          <structname>drm_crtc</structname> instance. The instance is allocated
          and zeroed by the driver, possibly as part of a larger structure, and
          registered with a call to <function>drm_crtc_init</function> with a
          pointer to CRTC functions.
        </para>
      </sect3>
    </sect2>
    <sect2>
      <title>Planes (struct <structname>drm_plane</structname>)</title>
      <para>
        A plane represents an image source that can be blended with or overlayed
	on top of a CRTC during the scanout process. Planes are associated with
	a frame buffer to crop a portion of the image memory (source) and
	optionally scale it to a destination size. The result is then blended
	with or overlayed on top of a CRTC.
      </para>
1224 1225 1226 1227 1228
      <para>
      The DRM core recognizes three types of planes:
      <itemizedlist>
        <listitem>
        DRM_PLANE_TYPE_PRIMARY represents a "main" plane for a CRTC.  Primary
T
Thierry Reding 已提交
1229
        planes are the planes operated upon by CRTC modesetting and flipping
D
Daniel Vetter 已提交
1230
	operations described in the page_flip hook in <structname>drm_crtc_funcs</structname>.
1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246
        </listitem>
        <listitem>
        DRM_PLANE_TYPE_CURSOR represents a "cursor" plane for a CRTC.  Cursor
        planes are the planes operated upon by the DRM_IOCTL_MODE_CURSOR and
        DRM_IOCTL_MODE_CURSOR2 ioctls.
        </listitem>
        <listitem>
        DRM_PLANE_TYPE_OVERLAY represents all non-primary, non-cursor planes.
        Some drivers refer to these types of planes as "sprites" internally.
        </listitem>
      </itemizedlist>
      For compatibility with legacy userspace, only overlay planes are made
      available to userspace by default.  Userspace clients may set the
      DRM_CLIENT_CAP_UNIVERSAL_PLANES client capability bit to indicate that
      they wish to receive a universal plane list containing all plane types.
      </para>
1247 1248 1249
      <sect3>
        <title>Plane Initialization</title>
        <para>
1250
          To create a plane, a KMS drivers allocates and
1251 1252
          zeroes an instances of struct <structname>drm_plane</structname>
          (possibly as part of a larger structure) and registers it with a call
1253
          to <function>drm_universal_plane_init</function>. The function takes a bitmask
1254
          of the CRTCs that can be associated with the plane, a pointer to the
1255 1256 1257 1258 1259 1260 1261 1262 1263 1264
          plane functions, a list of format supported formats, and the type of
          plane (primary, cursor, or overlay) being initialized.
        </para>
        <para>
          Cursor and overlay planes are optional.  All drivers should provide
          one primary plane per CRTC (although this requirement may change in
          the future); drivers that do not wish to provide special handling for
          primary planes may make use of the helper functions described in
          <xref linkend="drm-kms-planehelpers"/> to create and register a
          primary plane with standard capabilities.
1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403
        </para>
      </sect3>
    </sect2>
    <sect2>
      <title>Encoders (struct <structname>drm_encoder</structname>)</title>
      <para>
        An encoder takes pixel data from a CRTC and converts it to a format
	suitable for any attached connectors. On some devices, it may be
	possible to have a CRTC send data to more than one encoder. In that
	case, both encoders would receive data from the same scanout buffer,
	resulting in a "cloned" display configuration across the connectors
	attached to each encoder.
      </para>
      <sect3>
        <title>Encoder Initialization</title>
        <para>
          As for CRTCs, a KMS driver must create, initialize and register at
          least one struct <structname>drm_encoder</structname> instance. The
          instance is allocated and zeroed by the driver, possibly as part of a
          larger structure.
        </para>
        <para>
          Drivers must initialize the struct <structname>drm_encoder</structname>
          <structfield>possible_crtcs</structfield> and
          <structfield>possible_clones</structfield> fields before registering the
          encoder. Both fields are bitmasks of respectively the CRTCs that the
          encoder can be connected to, and sibling encoders candidate for cloning.
        </para>
        <para>
          After being initialized, the encoder must be registered with a call to
          <function>drm_encoder_init</function>. The function takes a pointer to
          the encoder functions and an encoder type. Supported types are
          <itemizedlist>
            <listitem>
              DRM_MODE_ENCODER_DAC for VGA and analog on DVI-I/DVI-A
              </listitem>
            <listitem>
              DRM_MODE_ENCODER_TMDS for DVI, HDMI and (embedded) DisplayPort
            </listitem>
            <listitem>
              DRM_MODE_ENCODER_LVDS for display panels
            </listitem>
            <listitem>
              DRM_MODE_ENCODER_TVDAC for TV output (Composite, S-Video, Component,
              SCART)
            </listitem>
            <listitem>
              DRM_MODE_ENCODER_VIRTUAL for virtual machine displays
            </listitem>
          </itemizedlist>
        </para>
        <para>
          Encoders must be attached to a CRTC to be used. DRM drivers leave
          encoders unattached at initialization time. Applications (or the fbdev
          compatibility layer when implemented) are responsible for attaching the
          encoders they want to use to a CRTC.
        </para>
      </sect3>
    </sect2>
    <sect2>
      <title>Connectors (struct <structname>drm_connector</structname>)</title>
      <para>
        A connector is the final destination for pixel data on a device, and
	usually connects directly to an external display device like a monitor
	or laptop panel. A connector can only be attached to one encoder at a
	time. The connector is also the structure where information about the
	attached display is kept, so it contains fields for display data, EDID
	data, DPMS &amp; connection status, and information about modes
	supported on the attached displays.
      </para>
      <sect3>
        <title>Connector Initialization</title>
        <para>
          Finally a KMS driver must create, initialize, register and attach at
          least one struct <structname>drm_connector</structname> instance. The
          instance is created as other KMS objects and initialized by setting the
          following fields.
        </para>
        <variablelist>
          <varlistentry>
            <term><structfield>interlace_allowed</structfield></term>
            <listitem><para>
              Whether the connector can handle interlaced modes.
            </para></listitem>
          </varlistentry>
          <varlistentry>
            <term><structfield>doublescan_allowed</structfield></term>
            <listitem><para>
              Whether the connector can handle doublescan.
            </para></listitem>
          </varlistentry>
          <varlistentry>
            <term><structfield>display_info
            </structfield></term>
            <listitem><para>
              Display information is filled from EDID information when a display
              is detected. For non hot-pluggable displays such as flat panels in
              embedded systems, the driver should initialize the
              <structfield>display_info</structfield>.<structfield>width_mm</structfield>
              and
              <structfield>display_info</structfield>.<structfield>height_mm</structfield>
              fields with the physical size of the display.
            </para></listitem>
          </varlistentry>
          <varlistentry>
            <term id="drm-kms-connector-polled"><structfield>polled</structfield></term>
            <listitem><para>
              Connector polling mode, a combination of
              <variablelist>
                <varlistentry>
                  <term>DRM_CONNECTOR_POLL_HPD</term>
                  <listitem><para>
                    The connector generates hotplug events and doesn't need to be
                    periodically polled. The CONNECT and DISCONNECT flags must not
                    be set together with the HPD flag.
                  </para></listitem>
                </varlistentry>
                <varlistentry>
                  <term>DRM_CONNECTOR_POLL_CONNECT</term>
                  <listitem><para>
                    Periodically poll the connector for connection.
                  </para></listitem>
                </varlistentry>
                <varlistentry>
                  <term>DRM_CONNECTOR_POLL_DISCONNECT</term>
                  <listitem><para>
                    Periodically poll the connector for disconnection.
                  </para></listitem>
                </varlistentry>
              </variablelist>
              Set to 0 for connectors that don't support connection status
              discovery.
            </para></listitem>
          </varlistentry>
        </variablelist>
        <para>
          The connector is then registered with a call to
          <function>drm_connector_init</function> with a pointer to the connector
          functions and a connector type, and exposed through sysfs with a call to
1404
          <function>drm_connector_register</function>.
1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540
        </para>
        <para>
          Supported connector types are
          <itemizedlist>
            <listitem>DRM_MODE_CONNECTOR_VGA</listitem>
            <listitem>DRM_MODE_CONNECTOR_DVII</listitem>
            <listitem>DRM_MODE_CONNECTOR_DVID</listitem>
            <listitem>DRM_MODE_CONNECTOR_DVIA</listitem>
            <listitem>DRM_MODE_CONNECTOR_Composite</listitem>
            <listitem>DRM_MODE_CONNECTOR_SVIDEO</listitem>
            <listitem>DRM_MODE_CONNECTOR_LVDS</listitem>
            <listitem>DRM_MODE_CONNECTOR_Component</listitem>
            <listitem>DRM_MODE_CONNECTOR_9PinDIN</listitem>
            <listitem>DRM_MODE_CONNECTOR_DisplayPort</listitem>
            <listitem>DRM_MODE_CONNECTOR_HDMIA</listitem>
            <listitem>DRM_MODE_CONNECTOR_HDMIB</listitem>
            <listitem>DRM_MODE_CONNECTOR_TV</listitem>
            <listitem>DRM_MODE_CONNECTOR_eDP</listitem>
            <listitem>DRM_MODE_CONNECTOR_VIRTUAL</listitem>
          </itemizedlist>
        </para>
        <para>
          Connectors must be attached to an encoder to be used. For devices that
          map connectors to encoders 1:1, the connector should be attached at
          initialization time with a call to
          <function>drm_mode_connector_attach_encoder</function>. The driver must
          also set the <structname>drm_connector</structname>
          <structfield>encoder</structfield> field to point to the attached
          encoder.
        </para>
        <para>
          Finally, drivers must initialize the connectors state change detection
          with a call to <function>drm_kms_helper_poll_init</function>. If at
          least one connector is pollable but can't generate hotplug interrupts
          (indicated by the DRM_CONNECTOR_POLL_CONNECT and
          DRM_CONNECTOR_POLL_DISCONNECT connector flags), a delayed work will
          automatically be queued to periodically poll for changes. Connectors
          that can generate hotplug interrupts must be marked with the
          DRM_CONNECTOR_POLL_HPD flag instead, and their interrupt handler must
          call <function>drm_helper_hpd_irq_event</function>. The function will
          queue a delayed work to check the state of all connectors, but no
          periodic polling will be done.
        </para>
      </sect3>
      <sect3>
        <title>Connector Operations</title>
        <note><para>
          Unless otherwise state, all operations are mandatory.
        </para></note>
        <sect4>
          <title>DPMS</title>
          <synopsis>void (*dpms)(struct drm_connector *connector, int mode);</synopsis>
          <para>
            The DPMS operation sets the power state of a connector. The mode
            argument is one of
            <itemizedlist>
              <listitem><para>DRM_MODE_DPMS_ON</para></listitem>
              <listitem><para>DRM_MODE_DPMS_STANDBY</para></listitem>
              <listitem><para>DRM_MODE_DPMS_SUSPEND</para></listitem>
              <listitem><para>DRM_MODE_DPMS_OFF</para></listitem>
            </itemizedlist>
          </para>
          <para>
            In all but DPMS_ON mode the encoder to which the connector is attached
            should put the display in low-power mode by driving its signals
            appropriately. If more than one connector is attached to the encoder
            care should be taken not to change the power state of other displays as
            a side effect. Low-power mode should be propagated to the encoders and
            CRTCs when all related connectors are put in low-power mode.
          </para>
        </sect4>
        <sect4>
          <title>Modes</title>
          <synopsis>int (*fill_modes)(struct drm_connector *connector, uint32_t max_width,
                      uint32_t max_height);</synopsis>
          <para>
            Fill the mode list with all supported modes for the connector. If the
            <parameter>max_width</parameter> and <parameter>max_height</parameter>
            arguments are non-zero, the implementation must ignore all modes wider
            than <parameter>max_width</parameter> or higher than
            <parameter>max_height</parameter>.
          </para>
          <para>
            The connector must also fill in this operation its
            <structfield>display_info</structfield>
            <structfield>width_mm</structfield> and
            <structfield>height_mm</structfield> fields with the connected display
            physical size in millimeters. The fields should be set to 0 if the value
            isn't known or is not applicable (for instance for projector devices).
          </para>
        </sect4>
        <sect4>
          <title>Connection Status</title>
          <para>
            The connection status is updated through polling or hotplug events when
            supported (see <xref linkend="drm-kms-connector-polled"/>). The status
            value is reported to userspace through ioctls and must not be used
            inside the driver, as it only gets initialized by a call to
            <function>drm_mode_getconnector</function> from userspace.
          </para>
          <synopsis>enum drm_connector_status (*detect)(struct drm_connector *connector,
                                        bool force);</synopsis>
          <para>
            Check to see if anything is attached to the connector. The
            <parameter>force</parameter> parameter is set to false whilst polling or
            to true when checking the connector due to user request.
            <parameter>force</parameter> can be used by the driver to avoid
            expensive, destructive operations during automated probing.
          </para>
          <para>
            Return connector_status_connected if something is connected to the
            connector, connector_status_disconnected if nothing is connected and
            connector_status_unknown if the connection state isn't known.
          </para>
          <para>
            Drivers should only return connector_status_connected if the connection
            status has really been probed as connected. Connectors that can't detect
            the connection status, or failed connection status probes, should return
            connector_status_unknown.
          </para>
        </sect4>
      </sect3>
    </sect2>
    <sect2>
      <title>Cleanup</title>
      <para>
        The DRM core manages its objects' lifetime. When an object is not needed
	anymore the core calls its destroy function, which must clean up and
	free every resource allocated for the object. Every
	<function>drm_*_init</function> call must be matched with a
	corresponding <function>drm_*_cleanup</function> call to cleanup CRTCs
	(<function>drm_crtc_cleanup</function>), planes
	(<function>drm_plane_cleanup</function>), encoders
	(<function>drm_encoder_cleanup</function>) and connectors
	(<function>drm_connector_cleanup</function>). Furthermore, connectors
	that have been added to sysfs must be removed by a call to
1541
	<function>drm_connector_unregister</function> before calling
1542 1543 1544 1545 1546 1547 1548 1549 1550 1551
	<function>drm_connector_cleanup</function>.
      </para>
      <para>
        Connectors state change detection must be cleanup up with a call to
	<function>drm_kms_helper_poll_fini</function>.
      </para>
    </sect2>
    <sect2>
      <title>Output discovery and initialization example</title>
      <programlisting><![CDATA[
1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585
void intel_crt_init(struct drm_device *dev)
{
	struct drm_connector *connector;
	struct intel_output *intel_output;

	intel_output = kzalloc(sizeof(struct intel_output), GFP_KERNEL);
	if (!intel_output)
		return;

	connector = &intel_output->base;
	drm_connector_init(dev, &intel_output->base,
			   &intel_crt_connector_funcs, DRM_MODE_CONNECTOR_VGA);

	drm_encoder_init(dev, &intel_output->enc, &intel_crt_enc_funcs,
			 DRM_MODE_ENCODER_DAC);

	drm_mode_connector_attach_encoder(&intel_output->base,
					  &intel_output->enc);

	/* Set up the DDC bus. */
	intel_output->ddc_bus = intel_i2c_create(dev, GPIOA, "CRTDDC_A");
	if (!intel_output->ddc_bus) {
		dev_printk(KERN_ERR, &dev->pdev->dev, "DDC bus registration "
			   "failed.\n");
		return;
	}

	intel_output->type = INTEL_OUTPUT_ANALOG;
	connector->interlace_allowed = 0;
	connector->doublescan_allowed = 0;

	drm_encoder_helper_add(&intel_output->enc, &intel_crt_helper_funcs);
	drm_connector_helper_add(connector, &intel_crt_connector_helper_funcs);

1586
	drm_connector_register(connector);
1587 1588 1589 1590 1591 1592 1593 1594
}]]></programlisting>
      <para>
        In the example above (taken from the i915 driver), a CRTC, connector and
        encoder combination is created. A device-specific i2c bus is also
        created for fetching EDID data and performing monitor detection. Once
        the process is complete, the new connector is registered with sysfs to
        make its properties available to applications.
      </para>
1595
    </sect2>
1596 1597 1598
    <sect2>
      <title>KMS API Functions</title>
!Edrivers/gpu/drm/drm_crtc.c
1599 1600 1601 1602
    </sect2>
    <sect2>
      <title>KMS Data Structures</title>
!Iinclude/drm/drm_crtc.h
1603
    </sect2>
1604 1605 1606 1607 1608 1609
    <sect2>
      <title>KMS Locking</title>
!Pdrivers/gpu/drm/drm_modeset_lock.c kms locking
!Iinclude/drm/drm_modeset_lock.h
!Edrivers/gpu/drm/drm_modeset_lock.c
    </sect2>
1610 1611
  </sect1>

1612
  <!-- Internals: kms helper functions -->
1613 1614

  <sect1>
1615
    <title>Mode Setting Helper Functions</title>
1616
    <para>
1617
      The plane, CRTC, encoder and connector functions provided by the drivers
1618 1619 1620 1621 1622 1623 1624
      implement the DRM API. They're called by the DRM core and ioctl handlers
      to handle device state changes and configuration request. As implementing
      those functions often requires logic not specific to drivers, mid-layer
      helper functions are available to avoid duplicating boilerplate code.
    </para>
    <para>
      The DRM core contains one mid-layer implementation. The mid-layer provides
1625 1626
      implementations of several plane, CRTC, encoder and connector functions
      (called from the top of the mid-layer) that pre-process requests and call
1627 1628 1629 1630 1631 1632 1633
      lower-level functions provided by the driver (at the bottom of the
      mid-layer). For instance, the
      <function>drm_crtc_helper_set_config</function> function can be used to
      fill the struct <structname>drm_crtc_funcs</structname>
      <structfield>set_config</structfield> field. When called, it will split
      the <methodname>set_config</methodname> operation in smaller, simpler
      operations and call the driver to handle them.
1634 1635
    </para>
    <para>
1636 1637 1638 1639 1640 1641 1642 1643 1644
      To use the mid-layer, drivers call <function>drm_crtc_helper_add</function>,
      <function>drm_encoder_helper_add</function> and
      <function>drm_connector_helper_add</function> functions to install their
      mid-layer bottom operations handlers, and fill the
      <structname>drm_crtc_funcs</structname>,
      <structname>drm_encoder_funcs</structname> and
      <structname>drm_connector_funcs</structname> structures with pointers to
      the mid-layer top API functions. Installing the mid-layer bottom operation
      handlers is best done right after registering the corresponding KMS object.
1645 1646
    </para>
    <para>
1647 1648 1649
      The mid-layer is not split between CRTC, encoder and connector operations.
      To use it, a driver must provide bottom functions for all of the three KMS
      entities.
1650
    </para>
1651
    <sect2>
1652
      <title>Legacy CRTC Helper Operations</title>
1653 1654 1655 1656 1657 1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 1749 1750 1751 1752 1753 1754 1755 1756 1757 1758 1759 1760 1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778 1779 1780 1781 1782 1783
      <itemizedlist>
        <listitem id="drm-helper-crtc-mode-fixup">
          <synopsis>bool (*mode_fixup)(struct drm_crtc *crtc,
                       const struct drm_display_mode *mode,
                       struct drm_display_mode *adjusted_mode);</synopsis>
          <para>
            Let CRTCs adjust the requested mode or reject it completely. This
            operation returns true if the mode is accepted (possibly after being
            adjusted) or false if it is rejected.
          </para>
          <para>
            The <methodname>mode_fixup</methodname> operation should reject the
            mode if it can't reasonably use it. The definition of "reasonable"
            is currently fuzzy in this context. One possible behaviour would be
            to set the adjusted mode to the panel timings when a fixed-mode
            panel is used with hardware capable of scaling. Another behaviour
            would be to accept any input mode and adjust it to the closest mode
            supported by the hardware (FIXME: This needs to be clarified).
          </para>
        </listitem>
        <listitem>
          <synopsis>int (*mode_set_base)(struct drm_crtc *crtc, int x, int y,
                     struct drm_framebuffer *old_fb)</synopsis>
          <para>
            Move the CRTC on the current frame buffer (stored in
            <literal>crtc-&gt;fb</literal>) to position (x,y). Any of the frame
            buffer, x position or y position may have been modified.
          </para>
          <para>
            This helper operation is optional. If not provided, the
            <function>drm_crtc_helper_set_config</function> function will fall
            back to the <methodname>mode_set</methodname> helper operation.
          </para>
          <note><para>
            FIXME: Why are x and y passed as arguments, as they can be accessed
            through <literal>crtc-&gt;x</literal> and
            <literal>crtc-&gt;y</literal>?
          </para></note>
        </listitem>
        <listitem>
          <synopsis>void (*prepare)(struct drm_crtc *crtc);</synopsis>
          <para>
            Prepare the CRTC for mode setting. This operation is called after
            validating the requested mode. Drivers use it to perform
            device-specific operations required before setting the new mode.
          </para>
        </listitem>
        <listitem>
          <synopsis>int (*mode_set)(struct drm_crtc *crtc, struct drm_display_mode *mode,
                struct drm_display_mode *adjusted_mode, int x, int y,
                struct drm_framebuffer *old_fb);</synopsis>
          <para>
            Set a new mode, position and frame buffer. Depending on the device
            requirements, the mode can be stored internally by the driver and
            applied in the <methodname>commit</methodname> operation, or
            programmed to the hardware immediately.
          </para>
          <para>
            The <methodname>mode_set</methodname> operation returns 0 on success
	    or a negative error code if an error occurs.
          </para>
        </listitem>
        <listitem>
          <synopsis>void (*commit)(struct drm_crtc *crtc);</synopsis>
          <para>
            Commit a mode. This operation is called after setting the new mode.
            Upon return the device must use the new mode and be fully
            operational.
          </para>
        </listitem>
      </itemizedlist>
    </sect2>
    <sect2>
      <title>Encoder Helper Operations</title>
      <itemizedlist>
        <listitem>
          <synopsis>bool (*mode_fixup)(struct drm_encoder *encoder,
                       const struct drm_display_mode *mode,
                       struct drm_display_mode *adjusted_mode);</synopsis>
          <para>
            Let encoders adjust the requested mode or reject it completely. This
            operation returns true if the mode is accepted (possibly after being
            adjusted) or false if it is rejected. See the
            <link linkend="drm-helper-crtc-mode-fixup">mode_fixup CRTC helper
            operation</link> for an explanation of the allowed adjustments.
          </para>
        </listitem>
        <listitem>
          <synopsis>void (*prepare)(struct drm_encoder *encoder);</synopsis>
          <para>
            Prepare the encoder for mode setting. This operation is called after
            validating the requested mode. Drivers use it to perform
            device-specific operations required before setting the new mode.
          </para>
        </listitem>
        <listitem>
          <synopsis>void (*mode_set)(struct drm_encoder *encoder,
                 struct drm_display_mode *mode,
                 struct drm_display_mode *adjusted_mode);</synopsis>
          <para>
            Set a new mode. Depending on the device requirements, the mode can
            be stored internally by the driver and applied in the
            <methodname>commit</methodname> operation, or programmed to the
            hardware immediately.
          </para>
        </listitem>
        <listitem>
          <synopsis>void (*commit)(struct drm_encoder *encoder);</synopsis>
          <para>
            Commit a mode. This operation is called after setting the new mode.
            Upon return the device must use the new mode and be fully
            operational.
          </para>
        </listitem>
      </itemizedlist>
    </sect2>
    <sect2>
      <title>Connector Helper Operations</title>
      <itemizedlist>
        <listitem>
          <synopsis>struct drm_encoder *(*best_encoder)(struct drm_connector *connector);</synopsis>
          <para>
            Return a pointer to the best encoder for the connecter. Device that
            map connectors to encoders 1:1 simply return the pointer to the
            associated encoder. This operation is mandatory.
          </para>
        </listitem>
        <listitem>
          <synopsis>int (*get_modes)(struct drm_connector *connector);</synopsis>
          <para>
            Fill the connector's <structfield>probed_modes</structfield> list
1784 1785 1786
            by parsing EDID data with <function>drm_add_edid_modes</function>,
            adding standard VESA DMT modes with <function>drm_add_modes_noedid</function>,
            or calling <function>drm_mode_probed_add</function> directly for every
1787 1788 1789
            supported mode and return the number of modes it has detected. This
            operation is mandatory.
          </para>
1790 1791 1792 1793 1794 1795 1796
          <para>
            Note that the caller function will automatically add standard VESA
            DMT modes up to 1024x768 if the <methodname>get_modes</methodname>
            helper operation returns no mode and if the connector status is
            connector_status_connected. There is no need to call
            <function>drm_add_edid_modes</function> manually in that case.
          </para>
1797 1798 1799 1800 1801
          <para>
            The <structfield>vrefresh</structfield> value is computed by
            <function>drm_helper_probe_single_connector_modes</function>.
          </para>
          <para>
1802
            When parsing EDID data, <function>drm_add_edid_modes</function> fills the
1803 1804 1805 1806 1807 1808 1809
            connector <structfield>display_info</structfield>
            <structfield>width_mm</structfield> and
            <structfield>height_mm</structfield> fields. When creating modes
            manually the <methodname>get_modes</methodname> helper operation must
            set the <structfield>display_info</structfield>
            <structfield>width_mm</structfield> and
            <structfield>height_mm</structfield> fields if they haven't been set
1810
            already (for instance at initialization time when a fixed-size panel is
1811 1812 1813 1814 1815 1816 1817 1818 1819 1820 1821
            attached to the connector). The mode <structfield>width_mm</structfield>
            and <structfield>height_mm</structfield> fields are only used internally
            during EDID parsing and should not be set when creating modes manually.
          </para>
        </listitem>
        <listitem>
          <synopsis>int (*mode_valid)(struct drm_connector *connector,
		  struct drm_display_mode *mode);</synopsis>
          <para>
            Verify whether a mode is valid for the connector. Return MODE_OK for
            supported modes and one of the enum drm_mode_status values (MODE_*)
1822
            for unsupported modes. This operation is optional.
1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834 1835 1836 1837 1838
          </para>
          <para>
            As the mode rejection reason is currently not used beside for
            immediately removing the unsupported mode, an implementation can
            return MODE_BAD regardless of the exact reason why the mode is not
            valid.
          </para>
          <note><para>
            Note that the <methodname>mode_valid</methodname> helper operation is
            only called for modes detected by the device, and
            <emphasis>not</emphasis> for modes set by the user through the CRTC
            <methodname>set_config</methodname> operation.
          </para></note>
        </listitem>
      </itemizedlist>
    </sect2>
1839 1840 1841 1842 1843 1844 1845 1846 1847 1848 1849 1850 1851 1852
    <sect2>
      <title>Atomic Modeset Helper Functions Reference</title>
      <sect3>
	<title>Overview</title>
!Pdrivers/gpu/drm/drm_atomic_helper.c overview
      </sect3>
      <sect3>
	<title>Implementing Asynchronous Atomic Commit</title>
!Pdrivers/gpu/drm/drm_atomic_helper.c implementing async commit
      </sect3>
      <sect3>
	<title>Atomic State Reset and Initialization</title>
!Pdrivers/gpu/drm/drm_atomic_helper.c atomic state reset and initialization
      </sect3>
R
Rob Clark 已提交
1853
!Iinclude/drm/drm_atomic_helper.h
1854
!Edrivers/gpu/drm/drm_atomic_helper.c
1855 1856 1857 1858 1859
    </sect2>
    <sect2>
      <title>Modeset Helper Reference for Common Vtables</title>
!Iinclude/drm/drm_modeset_helper_vtables.h
!Pinclude/drm/drm_modeset_helper_vtables.h overview
1860
    </sect2>
1861
    <sect2>
1862
      <title>Legacy CRTC/Modeset Helper Functions Reference</title>
1863
!Edrivers/gpu/drm/drm_crtc_helper.c
1864
!Pdrivers/gpu/drm/drm_crtc_helper.c overview
1865 1866 1867 1868 1869
    </sect2>
    <sect2>
      <title>Output Probing Helper Functions Reference</title>
!Pdrivers/gpu/drm/drm_probe_helper.c output probing helper overview
!Edrivers/gpu/drm/drm_probe_helper.c
1870
    </sect2>
1871 1872 1873 1874
    <sect2>
      <title>fbdev Helper Functions Reference</title>
!Pdrivers/gpu/drm/drm_fb_helper.c fbdev helpers
!Edrivers/gpu/drm/drm_fb_helper.c
D
Daniel Vetter 已提交
1875
!Iinclude/drm/drm_fb_helper.h
1876
    </sect2>
1877 1878 1879 1880 1881
    <sect2>
      <title>Display Port Helper Functions Reference</title>
!Pdrivers/gpu/drm/drm_dp_helper.c dp helpers
!Iinclude/drm/drm_dp_helper.h
!Edrivers/gpu/drm/drm_dp_helper.c
1882 1883 1884 1885 1886 1887
    </sect2>
    <sect2>
      <title>Display Port MST Helper Functions Reference</title>
!Pdrivers/gpu/drm/drm_dp_mst_topology.c dp mst helper
!Iinclude/drm/drm_dp_mst_helper.h
!Edrivers/gpu/drm/drm_dp_mst_topology.c
1888 1889 1890 1891 1892 1893
    </sect2>
    <sect2>
      <title>MIPI DSI Helper Functions Reference</title>
!Pdrivers/gpu/drm/drm_mipi_dsi.c dsi helpers
!Iinclude/drm/drm_mipi_dsi.h
!Edrivers/gpu/drm/drm_mipi_dsi.c
1894
    </sect2>
1895 1896 1897 1898
    <sect2>
      <title>EDID Helper Functions Reference</title>
!Edrivers/gpu/drm/drm_edid.c
    </sect2>
1899 1900 1901 1902 1903
    <sect2>
      <title>Rectangle Utilities Reference</title>
!Pinclude/drm/drm_rect.h rect utils
!Iinclude/drm/drm_rect.h
!Edrivers/gpu/drm/drm_rect.c
R
Rob Clark 已提交
1904 1905 1906 1907 1908 1909
    </sect2>
    <sect2>
      <title>Flip-work Helper Reference</title>
!Pinclude/drm/drm_flip_work.h flip utils
!Iinclude/drm/drm_flip_work.h
!Edrivers/gpu/drm/drm_flip_work.c
1910
    </sect2>
1911 1912 1913 1914 1915 1916 1917 1918 1919 1920 1921
    <sect2>
      <title>HDMI Infoframes Helper Reference</title>
      <para>
	Strictly speaking this is not a DRM helper library but generally useable
	by any driver interfacing with HDMI outputs like v4l or alsa drivers.
	But it nicely fits into the overall topic of mode setting helper
	libraries and hence is also included here.
      </para>
!Iinclude/linux/hdmi.h
!Edrivers/video/hdmi.c
    </sect2>
1922 1923
    <sect2>
      <title id="drm-kms-planehelpers">Plane Helper Reference</title>
1924 1925
!Edrivers/gpu/drm/drm_plane_helper.c
!Pdrivers/gpu/drm/drm_plane_helper.c overview
1926
    </sect2>
D
Dave Airlie 已提交
1927 1928 1929 1930
    <sect2>
	  <title>Tile group</title>
!Pdrivers/gpu/drm/drm_crtc.c Tile group
    </sect2>
1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942
    <sect2>
	<title>Bridges</title>
      <sect3>
	 <title>Overview</title>
!Pdrivers/gpu/drm/drm_bridge.c overview
      </sect3>
      <sect3>
	 <title>Default bridge callback sequence</title>
!Pdrivers/gpu/drm/drm_bridge.c bridge callbacks
      </sect3>
!Edrivers/gpu/drm/drm_bridge.c
    </sect2>
1943 1944
  </sect1>

1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964
  <!-- Internals: kms properties -->

  <sect1 id="drm-kms-properties">
    <title>KMS Properties</title>
    <para>
      Drivers may need to expose additional parameters to applications than
      those described in the previous sections. KMS supports attaching
      properties to CRTCs, connectors and planes and offers a userspace API to
      list, get and set the property values.
    </para>
    <para>
      Properties are identified by a name that uniquely defines the property
      purpose, and store an associated value. For all property types except blob
      properties the value is a 64-bit unsigned integer.
    </para>
    <para>
      KMS differentiates between properties and property instances. Drivers
      first create properties and then create and associate individual instances
      of those properties to objects. A property can be instantiated multiple
      times and associated with different objects. Values are stored in property
1965
      instances, and all other property information are stored in the property
1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 2043 2044 2045 2046 2047 2048 2049 2050 2051 2052 2053 2054 2055 2056 2057 2058
      and shared between all instances of the property.
    </para>
    <para>
      Every property is created with a type that influences how the KMS core
      handles the property. Supported property types are
      <variablelist>
        <varlistentry>
          <term>DRM_MODE_PROP_RANGE</term>
          <listitem><para>Range properties report their minimum and maximum
            admissible values. The KMS core verifies that values set by
            application fit in that range.</para></listitem>
        </varlistentry>
        <varlistentry>
          <term>DRM_MODE_PROP_ENUM</term>
          <listitem><para>Enumerated properties take a numerical value that
            ranges from 0 to the number of enumerated values defined by the
            property minus one, and associate a free-formed string name to each
            value. Applications can retrieve the list of defined value-name pairs
            and use the numerical value to get and set property instance values.
            </para></listitem>
        </varlistentry>
        <varlistentry>
          <term>DRM_MODE_PROP_BITMASK</term>
          <listitem><para>Bitmask properties are enumeration properties that
            additionally restrict all enumerated values to the 0..63 range.
            Bitmask property instance values combine one or more of the
            enumerated bits defined by the property.</para></listitem>
        </varlistentry>
        <varlistentry>
          <term>DRM_MODE_PROP_BLOB</term>
          <listitem><para>Blob properties store a binary blob without any format
            restriction. The binary blobs are created as KMS standalone objects,
            and blob property instance values store the ID of their associated
            blob object.</para>
	    <para>Blob properties are only used for the connector EDID property
	    and cannot be created by drivers.</para></listitem>
        </varlistentry>
      </variablelist>
    </para>
    <para>
      To create a property drivers call one of the following functions depending
      on the property type. All property creation functions take property flags
      and name, as well as type-specific arguments.
      <itemizedlist>
        <listitem>
          <synopsis>struct drm_property *drm_property_create_range(struct drm_device *dev, int flags,
                                               const char *name,
                                               uint64_t min, uint64_t max);</synopsis>
          <para>Create a range property with the given minimum and maximum
            values.</para>
        </listitem>
        <listitem>
          <synopsis>struct drm_property *drm_property_create_enum(struct drm_device *dev, int flags,
                                              const char *name,
                                              const struct drm_prop_enum_list *props,
                                              int num_values);</synopsis>
          <para>Create an enumerated property. The <parameter>props</parameter>
            argument points to an array of <parameter>num_values</parameter>
            value-name pairs.</para>
        </listitem>
        <listitem>
          <synopsis>struct drm_property *drm_property_create_bitmask(struct drm_device *dev,
                                                 int flags, const char *name,
                                                 const struct drm_prop_enum_list *props,
                                                 int num_values);</synopsis>
          <para>Create a bitmask property. The <parameter>props</parameter>
            argument points to an array of <parameter>num_values</parameter>
            value-name pairs.</para>
        </listitem>
      </itemizedlist>
    </para>
    <para>
      Properties can additionally be created as immutable, in which case they
      will be read-only for applications but can be modified by the driver. To
      create an immutable property drivers must set the DRM_MODE_PROP_IMMUTABLE
      flag at property creation time.
    </para>
    <para>
      When no array of value-name pairs is readily available at property
      creation time for enumerated or range properties, drivers can create
      the property using the <function>drm_property_create</function> function
      and manually add enumeration value-name pairs by calling the
      <function>drm_property_add_enum</function> function. Care must be taken to
      properly specify the property type through the <parameter>flags</parameter>
      argument.
    </para>
    <para>
      After creating properties drivers can attach property instances to CRTC,
      connector and plane objects by calling the
      <function>drm_object_attach_property</function>. The function takes a
      pointer to the target object, a pointer to the previously created property
      and an initial instance value.
    </para>
2059 2060 2061 2062 2063 2064 2065 2066 2067 2068 2069 2070 2071 2072 2073 2074 2075 2076
    <sect2>
	<title>Existing KMS Properties</title>
	<para>
	The following table gives description of drm properties exposed by various
	modules/drivers.
	</para>
	<table border="1" cellpadding="0" cellspacing="0">
	<tbody>
	<tr style="font-weight: bold;">
	<td valign="top" >Owner Module/Drivers</td>
	<td valign="top" >Group</td>
	<td valign="top" >Property Name</td>
	<td valign="top" >Type</td>
	<td valign="top" >Property Values</td>
	<td valign="top" >Object attached</td>
	<td valign="top" >Description/Restrictions</td>
	</tr>
	<tr>
2077 2078 2079 2080 2081 2082 2083 2084 2085 2086 2087 2088 2089 2090 2091 2092
	<td rowspan="37" valign="top" >DRM</td>
	<td valign="top" >Generic</td>
	<td valign="top" >“rotation”</td>
	<td valign="top" >BITMASK</td>
	<td valign="top" >{ 0, "rotate-0" },
	{ 1, "rotate-90" },
	{ 2, "rotate-180" },
	{ 3, "rotate-270" },
	{ 4, "reflect-x" },
	{ 5, "reflect-y" }</td>
	<td valign="top" >CRTC, Plane</td>
	<td valign="top" >rotate-(degrees) rotates the image by the specified amount in degrees
	in counter clockwise direction. reflect-x and reflect-y reflects the
	image along the specified axis prior to rotation</td>
	</tr>
	<tr>
2093
	<td rowspan="5" valign="top" >Connector</td>
2094 2095 2096 2097 2098 2099 2100 2101 2102 2103 2104 2105 2106 2107
	<td valign="top" >“EDID”</td>
	<td valign="top" >BLOB | IMMUTABLE</td>
	<td valign="top" >0</td>
	<td valign="top" >Connector</td>
	<td valign="top" >Contains id of edid blob ptr object.</td>
	</tr>
	<tr>
	<td valign="top" >“DPMS”</td>
	<td valign="top" >ENUM</td>
	<td valign="top" >{ “On”, “Standby”, “Suspend”, “Off” }</td>
	<td valign="top" >Connector</td>
	<td valign="top" >Contains DPMS operation mode value.</td>
	</tr>
	<tr>
2108 2109 2110 2111 2112 2113 2114
	<td valign="top" >“PATH”</td>
	<td valign="top" >BLOB | IMMUTABLE</td>
	<td valign="top" >0</td>
	<td valign="top" >Connector</td>
	<td valign="top" >Contains topology path to a connector.</td>
	</tr>
	<tr>
2115 2116 2117 2118 2119 2120 2121
	<td valign="top" >“TILE”</td>
	<td valign="top" >BLOB | IMMUTABLE</td>
	<td valign="top" >0</td>
	<td valign="top" >Connector</td>
	<td valign="top" >Contains tiling information for a connector.</td>
	</tr>
	<tr>
2122 2123 2124 2125 2126 2127 2128
	<td valign="top" >“CRTC_ID”</td>
	<td valign="top" >OBJECT</td>
	<td valign="top" >DRM_MODE_OBJECT_CRTC</td>
	<td valign="top" >Connector</td>
	<td valign="top" >CRTC that connector is attached to (atomic)</td>
	</tr>
	<tr>
R
Rob Clark 已提交
2129
	<td rowspan="11" valign="top" >Plane</td>
2130 2131 2132 2133 2134 2135 2136
	<td valign="top" >“type”</td>
	<td valign="top" >ENUM | IMMUTABLE</td>
	<td valign="top" >{ "Overlay", "Primary", "Cursor" }</td>
	<td valign="top" >Plane</td>
	<td valign="top" >Plane type</td>
	</tr>
	<tr>
R
Rob Clark 已提交
2137 2138 2139 2140 2141 2142 2143 2144 2145 2146 2147 2148 2149 2150 2151 2152 2153 2154 2155 2156 2157 2158 2159 2160 2161 2162 2163 2164 2165 2166 2167 2168 2169 2170 2171 2172 2173 2174 2175 2176 2177 2178 2179 2180 2181 2182 2183 2184 2185 2186 2187 2188 2189 2190 2191 2192 2193 2194 2195 2196 2197 2198 2199 2200 2201 2202 2203 2204 2205 2206
	<td valign="top" >“SRC_X”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=UINT_MAX</td>
	<td valign="top" >Plane</td>
	<td valign="top" >Scanout source x coordinate in 16.16 fixed point (atomic)</td>
	</tr>
	<tr>
	<td valign="top" >“SRC_Y”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=UINT_MAX</td>
	<td valign="top" >Plane</td>
	<td valign="top" >Scanout source y coordinate in 16.16 fixed point (atomic)</td>
	</tr>
	<tr>
	<td valign="top" >“SRC_W”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=UINT_MAX</td>
	<td valign="top" >Plane</td>
	<td valign="top" >Scanout source width in 16.16 fixed point (atomic)</td>
	</tr>
	<tr>
	<td valign="top" >“SRC_H”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=UINT_MAX</td>
	<td valign="top" >Plane</td>
	<td valign="top" >Scanout source height in 16.16 fixed point (atomic)</td>
	</tr>
	<tr>
	<td valign="top" >“CRTC_X”</td>
	<td valign="top" >SIGNED_RANGE</td>
	<td valign="top" >Min=INT_MIN, Max=INT_MAX</td>
	<td valign="top" >Plane</td>
	<td valign="top" >Scanout CRTC (destination) x coordinate (atomic)</td>
	</tr>
	<tr>
	<td valign="top" >“CRTC_Y”</td>
	<td valign="top" >SIGNED_RANGE</td>
	<td valign="top" >Min=INT_MIN, Max=INT_MAX</td>
	<td valign="top" >Plane</td>
	<td valign="top" >Scanout CRTC (destination) y coordinate (atomic)</td>
	</tr>
	<tr>
	<td valign="top" >“CRTC_W”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=UINT_MAX</td>
	<td valign="top" >Plane</td>
	<td valign="top" >Scanout CRTC (destination) width (atomic)</td>
	</tr>
	<tr>
	<td valign="top" >“CRTC_H”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=UINT_MAX</td>
	<td valign="top" >Plane</td>
	<td valign="top" >Scanout CRTC (destination) height (atomic)</td>
	</tr>
	<tr>
	<td valign="top" >“FB_ID”</td>
	<td valign="top" >OBJECT</td>
	<td valign="top" >DRM_MODE_OBJECT_FB</td>
	<td valign="top" >Plane</td>
	<td valign="top" >Scanout framebuffer (atomic)</td>
	</tr>
	<tr>
	<td valign="top" >“CRTC_ID”</td>
	<td valign="top" >OBJECT</td>
	<td valign="top" >DRM_MODE_OBJECT_CRTC</td>
	<td valign="top" >Plane</td>
	<td valign="top" >CRTC that plane is attached to (atomic)</td>
	</tr>
	<tr>
2207 2208 2209 2210 2211 2212 2213 2214 2215 2216 2217 2218 2219 2220 2221 2222 2223 2224 2225 2226 2227 2228 2229 2230 2231 2232 2233 2234 2235 2236 2237 2238 2239 2240 2241 2242 2243 2244 2245 2246 2247 2248 2249 2250 2251 2252 2253 2254 2255 2256 2257 2258 2259 2260 2261 2262 2263 2264 2265 2266 2267 2268 2269 2270 2271 2272 2273 2274 2275 2276 2277 2278 2279 2280 2281 2282 2283 2284 2285 2286 2287 2288 2289 2290 2291 2292 2293 2294 2295 2296 2297 2298 2299 2300 2301 2302 2303 2304 2305 2306 2307 2308 2309 2310 2311 2312 2313
	<td rowspan="2" valign="top" >DVI-I</td>
	<td valign="top" >“subconnector”</td>
	<td valign="top" >ENUM</td>
	<td valign="top" >{ “Unknown”, “DVI-D”, “DVI-A” }</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“select subconnector”</td>
	<td valign="top" >ENUM</td>
	<td valign="top" >{ “Automatic”, “DVI-D”, “DVI-A” }</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td rowspan="13" valign="top" >TV</td>
	<td valign="top" >“subconnector”</td>
	<td valign="top" >ENUM</td>
	<td valign="top" >{ "Unknown", "Composite", "SVIDEO", "Component", "SCART" }</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“select subconnector”</td>
	<td valign="top" >ENUM</td>
	<td valign="top" >{ "Automatic", "Composite", "SVIDEO", "Component", "SCART" }</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“mode”</td>
	<td valign="top" >ENUM</td>
	<td valign="top" >{ "NTSC_M", "NTSC_J", "NTSC_443", "PAL_B" } etc.</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“left margin”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=100</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“right margin”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=100</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“top margin”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=100</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“bottom margin”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=100</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“brightness”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=100</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“contrast”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=100</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“flicker reduction”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=100</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“overscan”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=100</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“saturation”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=100</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“hue”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=100</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
2314 2315 2316 2317 2318 2319 2320 2321 2322 2323 2324 2325 2326 2327 2328
	<td rowspan="2" valign="top" >Virtual GPU</td>
	<td valign="top" >“suggested X”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=0xffffffff</td>
	<td valign="top" >Connector</td>
	<td valign="top" >property to suggest an X offset for a connector</td>
	</tr>
	<tr>
	<td valign="top" >“suggested Y”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=0xffffffff</td>
	<td valign="top" >Connector</td>
	<td valign="top" >property to suggest an Y offset for a connector</td>
	</tr>
	<tr>
2329
	<td rowspan="3" valign="top" >Optional</td>
2330 2331 2332 2333 2334 2335 2336
	<td valign="top" >“scaling mode”</td>
	<td valign="top" >ENUM</td>
	<td valign="top" >{ "None", "Full", "Center", "Full aspect" }</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
2337 2338 2339 2340 2341 2342 2343 2344 2345
	<td valign="top" >"aspect ratio"</td>
	<td valign="top" >ENUM</td>
	<td valign="top" >{ "None", "4:3", "16:9" }</td>
	<td valign="top" >Connector</td>
	<td valign="top" >DRM property to set aspect ratio from user space app.
		This enum is made generic to allow addition of custom aspect
		ratios.</td>
	</tr>
	<tr>
2346 2347 2348 2349 2350 2351 2352
	<td valign="top" >“dirty”</td>
	<td valign="top" >ENUM | IMMUTABLE</td>
	<td valign="top" >{ "Off", "On", "Annotate" }</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
2353
	<td rowspan="20" valign="top" >i915</td>
2354
	<td rowspan="2" valign="top" >Generic</td>
2355 2356 2357 2358 2359 2360 2361 2362 2363 2364 2365 2366 2367 2368 2369 2370 2371 2372 2373 2374 2375 2376 2377 2378 2379 2380 2381 2382 2383 2384 2385 2386 2387 2388 2389 2390 2391 2392 2393 2394 2395 2396 2397 2398 2399 2400 2401 2402 2403 2404 2405 2406 2407 2408 2409 2410 2411 2412 2413 2414 2415 2416 2417 2418 2419 2420 2421 2422 2423 2424 2425 2426 2427 2428 2429 2430 2431 2432 2433 2434 2435 2436 2437 2438 2439 2440 2441 2442 2443 2444 2445 2446 2447 2448 2449 2450 2451 2452 2453 2454 2455 2456 2457 2458 2459 2460 2461 2462 2463 2464 2465 2466 2467 2468 2469 2470 2471 2472 2473 2474 2475 2476 2477 2478 2479 2480 2481 2482 2483 2484 2485 2486 2487 2488 2489 2490 2491 2492 2493 2494 2495 2496
	<td valign="top" >"Broadcast RGB"</td>
	<td valign="top" >ENUM</td>
	<td valign="top" >{ "Automatic", "Full", "Limited 16:235" }</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“audio”</td>
	<td valign="top" >ENUM</td>
	<td valign="top" >{ "force-dvi", "off", "auto", "on" }</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td rowspan="17" valign="top" >SDVO-TV</td>
	<td valign="top" >“mode”</td>
	<td valign="top" >ENUM</td>
	<td valign="top" >{ "NTSC_M", "NTSC_J", "NTSC_443", "PAL_B" } etc.</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >"left_margin"</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max= SDVO dependent</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >"right_margin"</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max= SDVO dependent</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >"top_margin"</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max= SDVO dependent</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >"bottom_margin"</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max= SDVO dependent</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“hpos”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max= SDVO dependent</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“vpos”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max= SDVO dependent</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“contrast”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max= SDVO dependent</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“saturation”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max= SDVO dependent</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“hue”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max= SDVO dependent</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“sharpness”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max= SDVO dependent</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“flicker_filter”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max= SDVO dependent</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“flicker_filter_adaptive”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max= SDVO dependent</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“flicker_filter_2d”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max= SDVO dependent</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“tv_chroma_filter”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max= SDVO dependent</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“tv_luma_filter”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max= SDVO dependent</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“dot_crawl”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=1</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >SDVO-TV/LVDS</td>
	<td valign="top" >“brightness”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max= SDVO dependent</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
2497 2498
	<td rowspan="2" valign="top" >CDV gma-500</td>
	<td rowspan="2" valign="top" >Generic</td>
2499 2500 2501 2502 2503 2504 2505 2506 2507 2508 2509 2510 2511 2512
	<td valign="top" >"Broadcast RGB"</td>
	<td valign="top" >ENUM</td>
	<td valign="top" >{ “Full”, “Limited 16:235” }</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >"Broadcast RGB"</td>
	<td valign="top" >ENUM</td>
	<td valign="top" >{ “off”, “auto”, “on” }</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
2513 2514
	<td rowspan="19" valign="top" >Poulsbo</td>
	<td rowspan="1" valign="top" >Generic</td>
2515 2516 2517 2518 2519 2520 2521 2522 2523 2524 2525 2526 2527 2528 2529 2530 2531 2532 2533 2534 2535 2536 2537 2538 2539 2540 2541 2542 2543 2544 2545 2546 2547 2548 2549 2550 2551 2552 2553 2554 2555 2556 2557 2558 2559 2560 2561 2562 2563 2564 2565 2566 2567 2568 2569 2570 2571 2572 2573 2574 2575 2576 2577 2578 2579 2580 2581 2582 2583 2584 2585 2586 2587 2588 2589 2590 2591 2592 2593 2594 2595 2596 2597 2598 2599 2600 2601 2602 2603 2604 2605 2606 2607 2608 2609 2610 2611 2612 2613 2614 2615 2616 2617 2618 2619 2620 2621 2622 2623 2624 2625 2626 2627 2628 2629 2630 2631 2632 2633 2634 2635 2636 2637 2638 2639 2640 2641 2642 2643 2644 2645 2646 2647 2648 2649 2650 2651 2652 2653 2654 2655 2656 2657 2658 2659 2660 2661 2662 2663 2664 2665 2666 2667 2668 2669 2670 2671 2672 2673 2674 2675 2676 2677 2678 2679 2680 2681 2682 2683 2684 2685 2686 2687 2688 2689 2690 2691 2692 2693 2694 2695 2696 2697 2698 2699 2700 2701 2702 2703 2704 2705 2706 2707 2708 2709 2710 2711 2712 2713 2714 2715 2716 2717 2718 2719 2720 2721 2722 2723 2724 2725 2726 2727 2728 2729 2730 2731 2732 2733 2734 2735 2736 2737 2738 2739 2740 2741 2742 2743 2744 2745 2746 2747
	<td valign="top" >“backlight”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=100</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td rowspan="17" valign="top" >SDVO-TV</td>
	<td valign="top" >“mode”</td>
	<td valign="top" >ENUM</td>
	<td valign="top" >{ "NTSC_M", "NTSC_J", "NTSC_443", "PAL_B" } etc.</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >"left_margin"</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max= SDVO dependent</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >"right_margin"</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max= SDVO dependent</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >"top_margin"</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max= SDVO dependent</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >"bottom_margin"</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max= SDVO dependent</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“hpos”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max= SDVO dependent</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“vpos”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max= SDVO dependent</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“contrast”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max= SDVO dependent</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“saturation”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max= SDVO dependent</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“hue”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max= SDVO dependent</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“sharpness”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max= SDVO dependent</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“flicker_filter”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max= SDVO dependent</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“flicker_filter_adaptive”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max= SDVO dependent</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“flicker_filter_2d”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max= SDVO dependent</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“tv_chroma_filter”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max= SDVO dependent</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“tv_luma_filter”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max= SDVO dependent</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“dot_crawl”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=1</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >SDVO-TV/LVDS</td>
	<td valign="top" >“brightness”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max= SDVO dependent</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td rowspan="11" valign="top" >armada</td>
	<td rowspan="2" valign="top" >CRTC</td>
	<td valign="top" >"CSC_YUV"</td>
	<td valign="top" >ENUM</td>
	<td valign="top" >{ "Auto" , "CCIR601", "CCIR709" }</td>
	<td valign="top" >CRTC</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >"CSC_RGB"</td>
	<td valign="top" >ENUM</td>
	<td valign="top" >{ "Auto", "Computer system", "Studio" }</td>
	<td valign="top" >CRTC</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td rowspan="9" valign="top" >Overlay</td>
	<td valign="top" >"colorkey"</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=0xffffff</td>
	<td valign="top" >Plane</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >"colorkey_min"</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=0xffffff</td>
	<td valign="top" >Plane</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >"colorkey_max"</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=0xffffff</td>
	<td valign="top" >Plane</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >"colorkey_val"</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=0xffffff</td>
	<td valign="top" >Plane</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >"colorkey_alpha"</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=0xffffff</td>
	<td valign="top" >Plane</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >"colorkey_mode"</td>
	<td valign="top" >ENUM</td>
	<td valign="top" >{ "disabled", "Y component", "U component"
	, "V component", "RGB", “R component", "G component", "B component" }</td>
	<td valign="top" >Plane</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >"brightness"</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=256 + 255</td>
	<td valign="top" >Plane</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >"contrast"</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=0x7fff</td>
	<td valign="top" >Plane</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >"saturation"</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=0x7fff</td>
	<td valign="top" >Plane</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td rowspan="2" valign="top" >exynos</td>
	<td valign="top" >CRTC</td>
	<td valign="top" >“mode”</td>
	<td valign="top" >ENUM</td>
	<td valign="top" >{ "normal", "blank" }</td>
	<td valign="top" >CRTC</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >Overlay</td>
	<td valign="top" >“zpos”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=MAX_PLANE-1</td>
	<td valign="top" >Plane</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
2748
	<td rowspan="2" valign="top" >i2c/ch7006_drv</td>
2749 2750 2751 2752 2753 2754 2755 2756
	<td valign="top" >Generic</td>
	<td valign="top" >“scale”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=2</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
2757
	<td rowspan="1" valign="top" >TV</td>
2758 2759 2760 2761 2762 2763 2764 2765
	<td valign="top" >“mode”</td>
	<td valign="top" >ENUM</td>
	<td valign="top" >{ "PAL", "PAL-M","PAL-N"}, ”PAL-Nc"
	, "PAL-60", "NTSC-M", "NTSC-J" }</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
2766
	<td rowspan="15" valign="top" >nouveau</td>
2767 2768 2769 2770 2771 2772 2773 2774 2775 2776 2777 2778 2779 2780 2781 2782 2783 2784 2785 2786 2787 2788 2789 2790 2791 2792 2793 2794 2795 2796 2797 2798 2799 2800 2801 2802 2803 2804 2805 2806 2807 2808 2809 2810 2811 2812 2813 2814 2815 2816 2817 2818 2819 2820 2821 2822 2823 2824 2825 2826 2827 2828 2829 2830 2831 2832 2833 2834 2835 2836 2837 2838 2839 2840 2841 2842 2843 2844 2845 2846 2847 2848 2849 2850 2851 2852 2853 2854 2855 2856 2857 2858 2859 2860 2861 2862 2863 2864 2865 2866 2867 2868 2869 2870 2871 2872 2873 2874
	<td rowspan="6" valign="top" >NV10 Overlay</td>
	<td valign="top" >"colorkey"</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=0x01ffffff</td>
	<td valign="top" >Plane</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“contrast”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=8192-1</td>
	<td valign="top" >Plane</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“brightness”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=1024</td>
	<td valign="top" >Plane</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“hue”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=359</td>
	<td valign="top" >Plane</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“saturation”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=8192-1</td>
	<td valign="top" >Plane</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“iturbt_709”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=1</td>
	<td valign="top" >Plane</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td rowspan="2" valign="top" >Nv04 Overlay</td>
	<td valign="top" >“colorkey”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=0x01ffffff</td>
	<td valign="top" >Plane</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“brightness”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=1024</td>
	<td valign="top" >Plane</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td rowspan="7" valign="top" >Display</td>
	<td valign="top" >“dithering mode”</td>
	<td valign="top" >ENUM</td>
	<td valign="top" >{ "auto", "off", "on" }</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“dithering depth”</td>
	<td valign="top" >ENUM</td>
	<td valign="top" >{ "auto", "off", "on", "static 2x2", "dynamic 2x2", "temporal" }</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“underscan”</td>
	<td valign="top" >ENUM</td>
	<td valign="top" >{ "auto", "6 bpc", "8 bpc" }</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“underscan hborder”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=128</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“underscan vborder”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=128</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“vibrant hue”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=180</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >“color vibrance”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=200</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
2875
	<td valign="top" >omap</td>
2876
	<td valign="top" >Generic</td>
2877 2878 2879 2880 2881 2882 2883 2884 2885 2886 2887 2888 2889 2890 2891 2892
	<td valign="top" >“zorder”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=3</td>
	<td valign="top" >CRTC, Plane</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >qxl</td>
	<td valign="top" >Generic</td>
	<td valign="top" >“hotplug_mode_update"</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=1</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
2893
	<td rowspan="9" valign="top" >radeon</td>
2894 2895 2896 2897 2898 2899 2900 2901 2902 2903 2904 2905 2906 2907 2908 2909 2910 2911 2912 2913 2914 2915 2916 2917 2918 2919 2920 2921 2922 2923 2924 2925 2926 2927 2928 2929 2930 2931 2932 2933 2934 2935 2936 2937 2938 2939 2940 2941 2942 2943 2944 2945 2946 2947 2948 2949 2950 2951 2952 2953 2954 2955 2956 2957 2958 2959 2960 2961 2962 2963 2964 2965 2966 2967 2968 2969 2970 2971 2972 2973 2974 2975 2976 2977 2978 2979 2980 2981 2982 2983 2984 2985 2986 2987 2988 2989
	<td valign="top" >DVI-I</td>
	<td valign="top" >“coherent”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=1</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >DAC enable load detect</td>
	<td valign="top" >“load detection”</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=1</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >TV Standard</td>
	<td valign="top" >"tv standard"</td>
	<td valign="top" >ENUM</td>
	<td valign="top" >{ "ntsc", "pal", "pal-m", "pal-60", "ntsc-j"
	, "scart-pal", "pal-cn", "secam" }</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >legacy TMDS PLL detect</td>
	<td valign="top" >"tmds_pll"</td>
	<td valign="top" >ENUM</td>
	<td valign="top" >{ "driver", "bios" }</td>
	<td valign="top" >-</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td rowspan="3" valign="top" >Underscan</td>
	<td valign="top" >"underscan"</td>
	<td valign="top" >ENUM</td>
	<td valign="top" >{ "off", "on", "auto" }</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >"underscan hborder"</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=128</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >"underscan vborder"</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=128</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >Audio</td>
	<td valign="top" >“audio”</td>
	<td valign="top" >ENUM</td>
	<td valign="top" >{ "off", "on", "auto" }</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >FMT Dithering</td>
	<td valign="top" >“dither”</td>
	<td valign="top" >ENUM</td>
	<td valign="top" >{ "off", "on" }</td>
	<td valign="top" >Connector</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td rowspan="3" valign="top" >rcar-du</td>
	<td rowspan="3" valign="top" >Generic</td>
	<td valign="top" >"alpha"</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=255</td>
	<td valign="top" >Plane</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >"colorkey"</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=0, Max=0x01ffffff</td>
	<td valign="top" >Plane</td>
	<td valign="top" >TBD</td>
	</tr>
	<tr>
	<td valign="top" >"zpos"</td>
	<td valign="top" >RANGE</td>
	<td valign="top" >Min=1, Max=7</td>
	<td valign="top" >Plane</td>
	<td valign="top" >TBD</td>
	</tr>
	</tbody>
	</table>
    </sect2>
2990 2991
  </sect1>

2992 2993 2994 2995 2996 2997 2998 2999 3000 3001 3002 3003 3004 3005 3006 3007 3008 3009 3010 3011 3012 3013 3014 3015 3016 3017 3018 3019 3020 3021 3022 3023 3024 3025 3026 3027 3028
  <!-- Internals: vertical blanking -->

  <sect1 id="drm-vertical-blank">
    <title>Vertical Blanking</title>
    <para>
      Vertical blanking plays a major role in graphics rendering. To achieve
      tear-free display, users must synchronize page flips and/or rendering to
      vertical blanking. The DRM API offers ioctls to perform page flips
      synchronized to vertical blanking and wait for vertical blanking.
    </para>
    <para>
      The DRM core handles most of the vertical blanking management logic, which
      involves filtering out spurious interrupts, keeping race-free blanking
      counters, coping with counter wrap-around and resets and keeping use
      counts. It relies on the driver to generate vertical blanking interrupts
      and optionally provide a hardware vertical blanking counter. Drivers must
      implement the following operations.
    </para>
    <itemizedlist>
      <listitem>
        <synopsis>int (*enable_vblank) (struct drm_device *dev, int crtc);
void (*disable_vblank) (struct drm_device *dev, int crtc);</synopsis>
        <para>
	  Enable or disable vertical blanking interrupts for the given CRTC.
	</para>
      </listitem>
      <listitem>
        <synopsis>u32 (*get_vblank_counter) (struct drm_device *dev, int crtc);</synopsis>
        <para>
	  Retrieve the value of the vertical blanking counter for the given
	  CRTC. If the hardware maintains a vertical blanking counter its value
	  should be returned. Otherwise drivers can use the
	  <function>drm_vblank_count</function> helper function to handle this
	  operation.
	</para>
      </listitem>
    </itemizedlist>
3029
    <para>
3030 3031 3032 3033 3034 3035 3036 3037 3038 3039
      Drivers must initialize the vertical blanking handling core with a call to
      <function>drm_vblank_init</function> in their
      <methodname>load</methodname> operation. The function will set the struct
      <structname>drm_device</structname>
      <structfield>vblank_disable_allowed</structfield> field to 0. This will
      keep vertical blanking interrupts enabled permanently until the first mode
      set operation, where <structfield>vblank_disable_allowed</structfield> is
      set to 1. The reason behind this is not clear. Drivers can set the field
      to 1 after <function>calling drm_vblank_init</function> to make vertical
      blanking interrupts dynamically managed from the beginning.
3040
    </para>
3041 3042 3043 3044 3045 3046 3047 3048 3049 3050 3051 3052 3053 3054 3055
    <para>
      Vertical blanking interrupts can be enabled by the DRM core or by drivers
      themselves (for instance to handle page flipping operations). The DRM core
      maintains a vertical blanking use count to ensure that the interrupts are
      not disabled while a user still needs them. To increment the use count,
      drivers call <function>drm_vblank_get</function>. Upon return vertical
      blanking interrupts are guaranteed to be enabled.
    </para>
    <para>
      To decrement the use count drivers call
      <function>drm_vblank_put</function>. Only when the use count drops to zero
      will the DRM core disable the vertical blanking interrupts after a delay
      by scheduling a timer. The delay is accessible through the vblankoffdelay
      module parameter or the <varname>drm_vblank_offdelay</varname> global
      variable and expressed in milliseconds. Its default value is 5000 ms.
3056
      Zero means never disable, and a negative value means disable immediately.
3057 3058 3059 3060 3061 3062
      Drivers may override the behaviour by setting the
      <structname>drm_device</structname>
      <structfield>vblank_disable_immediate</structfield> flag, which when set
      causes vblank interrupts to be disabled immediately regardless of the
      drm_vblank_offdelay value. The flag should only be set if there's a
      properly working hardware vblank counter present.
3063 3064 3065 3066 3067 3068 3069 3070 3071 3072 3073
    </para>
    <para>
      When a vertical blanking interrupt occurs drivers only need to call the
      <function>drm_handle_vblank</function> function to account for the
      interrupt.
    </para>
    <para>
      Resources allocated by <function>drm_vblank_init</function> must be freed
      with a call to <function>drm_vblank_cleanup</function> in the driver
      <methodname>unload</methodname> operation handler.
    </para>
D
Daniel Vetter 已提交
3074 3075 3076
    <sect2>
      <title>Vertical Blanking and Interrupt Handling Functions Reference</title>
!Edrivers/gpu/drm/drm_irq.c
3077
!Finclude/drm/drmP.h drm_crtc_vblank_waitqueue
D
Daniel Vetter 已提交
3078
    </sect2>
3079 3080 3081
  </sect1>

  <!-- Internals: open/close, file operations and ioctls -->
3082

3083 3084
  <sect1>
    <title>Open/Close, File Operations and IOCTLs</title>
3085
    <sect2>
3086 3087 3088 3089 3090 3091 3092 3093
      <title>Open and Close</title>
      <synopsis>int (*firstopen) (struct drm_device *);
void (*lastclose) (struct drm_device *);
int (*open) (struct drm_device *, struct drm_file *);
void (*preclose) (struct drm_device *, struct drm_file *);
void (*postclose) (struct drm_device *, struct drm_file *);</synopsis>
      <abstract>Open and close handlers. None of those methods are mandatory.
      </abstract>
3094
      <para>
3095
        The <methodname>firstopen</methodname> method is called by the DRM core
3096 3097 3098 3099 3100
	for legacy UMS (User Mode Setting) drivers only when an application
	opens a device that has no other opened file handle. UMS drivers can
	implement it to acquire device resources. KMS drivers can't use the
	method and must acquire resources in the <methodname>load</methodname>
	method instead.
3101 3102
      </para>
      <para>
3103 3104 3105 3106 3107
	Similarly the <methodname>lastclose</methodname> method is called when
	the last application holding a file handle opened on the device closes
	it, for both UMS and KMS drivers. Additionally, the method is also
	called at module unload time or, for hot-pluggable devices, when the
	device is unplugged. The <methodname>firstopen</methodname> and
3108
	<methodname>lastclose</methodname> calls can thus be unbalanced.
3109 3110
      </para>
      <para>
3111 3112 3113 3114 3115 3116 3117 3118 3119 3120 3121 3122 3123 3124 3125 3126 3127 3128 3129 3130 3131 3132 3133 3134 3135
        The <methodname>open</methodname> method is called every time the device
	is opened by an application. Drivers can allocate per-file private data
	in this method and store them in the struct
	<structname>drm_file</structname> <structfield>driver_priv</structfield>
	field. Note that the <methodname>open</methodname> method is called
	before <methodname>firstopen</methodname>.
      </para>
      <para>
        The close operation is split into <methodname>preclose</methodname> and
	<methodname>postclose</methodname> methods. Drivers must stop and
	cleanup all per-file operations in the <methodname>preclose</methodname>
	method. For instance pending vertical blanking and page flip events must
	be cancelled. No per-file operation is allowed on the file handle after
	returning from the <methodname>preclose</methodname> method.
      </para>
      <para>
        Finally the <methodname>postclose</methodname> method is called as the
	last step of the close operation, right before calling the
	<methodname>lastclose</methodname> method if no other open file handle
	exists for the device. Drivers that have allocated per-file private data
	in the <methodname>open</methodname> method should free it here.
      </para>
      <para>
        The <methodname>lastclose</methodname> method should restore CRTC and
	plane properties to default value, so that a subsequent open of the
3136 3137
	device will not inherit state from the previous user. It can also be
	used to execute delayed power switching state changes, e.g. in
3138 3139 3140 3141 3142
	conjunction with the vga_switcheroo infrastructure (see
	<xref linkend="vga_switcheroo"/>). Beyond that KMS drivers should not
	do any further cleanup. Only legacy UMS drivers might need to clean up
	device state so that the vga console or an independent fbdev driver
	could take over.
3143 3144 3145
      </para>
    </sect2>
    <sect2>
3146 3147 3148
      <title>File Operations</title>
      <synopsis>const struct file_operations *fops</synopsis>
      <abstract>File operations for the DRM device node.</abstract>
3149
      <para>
3150 3151 3152 3153 3154 3155 3156 3157 3158 3159 3160 3161 3162 3163
        Drivers must define the file operations structure that forms the DRM
	userspace API entry point, even though most of those operations are
	implemented in the DRM core. The <methodname>open</methodname>,
	<methodname>release</methodname> and <methodname>ioctl</methodname>
	operations are handled by
	<programlisting>
	.owner = THIS_MODULE,
	.open = drm_open,
	.release = drm_release,
	.unlocked_ioctl = drm_ioctl,
  #ifdef CONFIG_COMPAT
	.compat_ioctl = drm_compat_ioctl,
  #endif
        </programlisting>
3164 3165
      </para>
      <para>
3166 3167 3168 3169
        Drivers that implement private ioctls that requires 32/64bit
	compatibility support must provide their own
	<methodname>compat_ioctl</methodname> handler that processes private
	ioctls and calls <function>drm_compat_ioctl</function> for core ioctls.
3170 3171
      </para>
      <para>
3172 3173 3174 3175 3176 3177 3178 3179 3180 3181 3182 3183 3184 3185 3186 3187 3188 3189 3190 3191 3192 3193 3194 3195 3196 3197 3198 3199 3200 3201 3202 3203 3204 3205 3206 3207 3208 3209 3210 3211 3212 3213 3214 3215 3216 3217 3218 3219 3220 3221 3222 3223 3224 3225 3226 3227 3228 3229 3230 3231 3232 3233 3234 3235 3236 3237 3238 3239
        The <methodname>read</methodname> and <methodname>poll</methodname>
	operations provide support for reading DRM events and polling them. They
	are implemented by
	<programlisting>
	.poll = drm_poll,
	.read = drm_read,
	.llseek = no_llseek,
	</programlisting>
      </para>
      <para>
        The memory mapping implementation varies depending on how the driver
	manages memory. Pre-GEM drivers will use <function>drm_mmap</function>,
	while GEM-aware drivers will use <function>drm_gem_mmap</function>. See
	<xref linkend="drm-gem"/>.
	<programlisting>
	.mmap = drm_gem_mmap,
	</programlisting>
      </para>
      <para>
        No other file operation is supported by the DRM API.
      </para>
    </sect2>
    <sect2>
      <title>IOCTLs</title>
      <synopsis>struct drm_ioctl_desc *ioctls;
int num_ioctls;</synopsis>
      <abstract>Driver-specific ioctls descriptors table.</abstract>
      <para>
        Driver-specific ioctls numbers start at DRM_COMMAND_BASE. The ioctls
	descriptors table is indexed by the ioctl number offset from the base
	value. Drivers can use the DRM_IOCTL_DEF_DRV() macro to initialize the
	table entries.
      </para>
      <para>
        <programlisting>DRM_IOCTL_DEF_DRV(ioctl, func, flags)</programlisting>
	<para>
	  <parameter>ioctl</parameter> is the ioctl name. Drivers must define
	  the DRM_##ioctl and DRM_IOCTL_##ioctl macros to the ioctl number
	  offset from DRM_COMMAND_BASE and the ioctl number respectively. The
	  first macro is private to the device while the second must be exposed
	  to userspace in a public header.
	</para>
	<para>
	  <parameter>func</parameter> is a pointer to the ioctl handler function
	  compatible with the <type>drm_ioctl_t</type> type.
	  <programlisting>typedef int drm_ioctl_t(struct drm_device *dev, void *data,
		struct drm_file *file_priv);</programlisting>
	</para>
	<para>
	  <parameter>flags</parameter> is a bitmask combination of the following
	  values. It restricts how the ioctl is allowed to be called.
	  <itemizedlist>
	    <listitem><para>
	      DRM_AUTH - Only authenticated callers allowed
	    </para></listitem>
	    <listitem><para>
	      DRM_MASTER - The ioctl can only be called on the master file
	      handle
	    </para></listitem>
            <listitem><para>
	      DRM_ROOT_ONLY - Only callers with the SYSADMIN capability allowed
	    </para></listitem>
            <listitem><para>
	      DRM_CONTROL_ALLOW - The ioctl can only be called on a control
	      device
	    </para></listitem>
            <listitem><para>
	      DRM_UNLOCKED - The ioctl handler will be called without locking
3240 3241 3242
	      the DRM global mutex. This is the enforced default for kms drivers
	      (i.e. using the DRIVER_MODESET flag) and hence shouldn't be used
	      any more for new drivers.
3243 3244 3245
	    </para></listitem>
	  </itemizedlist>
	</para>
3246
      </para>
D
Daniel Vetter 已提交
3247
!Edrivers/gpu/drm/drm_ioctl.c
3248 3249 3250
    </sect2>
  </sect1>
  <sect1>
3251
    <title>Legacy Support Code</title>
3252
    <para>
3253
      The section very briefly covers some of the old legacy support code which
3254 3255
      is only used by old DRM drivers which have done a so-called shadow-attach
      to the underlying device instead of registering as a real driver. This
3256
      also includes some of the old generic buffer management and command
3257
      submission code. Do not use any of this in new and modern drivers.
3258 3259
    </para>

3260 3261 3262 3263 3264 3265 3266 3267 3268 3269 3270 3271 3272 3273 3274 3275 3276 3277 3278 3279 3280 3281 3282 3283 3284 3285 3286 3287
    <sect2>
      <title>Legacy Suspend/Resume</title>
      <para>
	The DRM core provides some suspend/resume code, but drivers wanting full
	suspend/resume support should provide save() and restore() functions.
	These are called at suspend, hibernate, or resume time, and should perform
	any state save or restore required by your device across suspend or
	hibernate states.
      </para>
      <synopsis>int (*suspend) (struct drm_device *, pm_message_t state);
  int (*resume) (struct drm_device *);</synopsis>
      <para>
	Those are legacy suspend and resume methods which
	<emphasis>only</emphasis> work with the legacy shadow-attach driver
	registration functions. New driver should use the power management
	interface provided by their bus type (usually through
	the struct <structname>device_driver</structname> dev_pm_ops) and set
	these methods to NULL.
      </para>
    </sect2>

    <sect2>
      <title>Legacy DMA Services</title>
      <para>
	This should cover how DMA mapping etc. is supported by the core.
	These functions are deprecated and should not be used.
      </para>
    </sect2>
3288 3289 3290
  </sect1>
  </chapter>

3291 3292 3293 3294 3295 3296 3297 3298 3299 3300 3301 3302 3303 3304 3305 3306 3307 3308 3309 3310 3311 3312 3313 3314 3315 3316 3317 3318 3319
<!-- TODO

- Add a glossary
- Document the struct_mutex catch-all lock
- Document connector properties

- Why is the load method optional?
- What are drivers supposed to set the initial display state to, and how?
  Connector's DPMS states are not initialized and are thus equal to
  DRM_MODE_DPMS_ON. The fbcon compatibility layer calls
  drm_helper_disable_unused_functions(), which disables unused encoders and
  CRTCs, but doesn't touch the connectors' DPMS state, and
  drm_helper_connector_dpms() in reaction to fbdev blanking events. Do drivers
  that don't implement (or just don't use) fbcon compatibility need to call
  those functions themselves?
- KMS drivers must call drm_vblank_pre_modeset() and drm_vblank_post_modeset()
  around mode setting. Should this be done in the DRM core?
- vblank_disable_allowed is set to 1 in the first drm_vblank_post_modeset()
  call and never set back to 0. It seems to be safe to permanently set it to 1
  in drm_vblank_init() for KMS driver, and it might be safe for UMS drivers as
  well. This should be investigated.
- crtc and connector .save and .restore operations are only used internally in
  drivers, should they be removed from the core?
- encoder mid-layer .save and .restore operations are only used internally in
  drivers, should they be removed from the core?
- encoder mid-layer .detect operation is only used internally in drivers,
  should it be removed from the core?
-->

3320 3321 3322 3323 3324 3325 3326
  <!-- External interfaces -->

  <chapter id="drmExternals">
    <title>Userland interfaces</title>
    <para>
      The DRM core exports several interfaces to applications,
      generally intended to be used through corresponding libdrm
3327
      wrapper functions.  In addition, drivers export device-specific
3328
      interfaces for use by userspace drivers &amp; device-aware
3329 3330 3331 3332 3333 3334 3335 3336
      applications through ioctls and sysfs files.
    </para>
    <para>
      External interfaces include: memory mapping, context management,
      DMA operations, AGP management, vblank control, fence
      management, memory management, and output management.
    </para>
    <para>
3337 3338
      Cover generic ioctls and sysfs layout here.  We only need high-level
      info, since man pages should cover the rest.
3339
    </para>
3340

3341 3342 3343 3344 3345 3346 3347 3348
  <!-- External: render nodes -->

    <sect1>
      <title>Render nodes</title>
      <para>
        DRM core provides multiple character-devices for user-space to use.
        Depending on which device is opened, user-space can perform a different
        set of operations (mainly ioctls). The primary node is always created
3349 3350
        and called card&lt;num&gt;. Additionally, a currently
        unused control node, called controlD&lt;num&gt; is also
3351 3352 3353 3354 3355 3356 3357 3358 3359 3360 3361 3362 3363 3364
        created. The primary node provides all legacy operations and
        historically was the only interface used by userspace. With KMS, the
        control node was introduced. However, the planned KMS control interface
        has never been written and so the control node stays unused to date.
      </para>
      <para>
        With the increased use of offscreen renderers and GPGPU applications,
        clients no longer require running compositors or graphics servers to
        make use of a GPU. But the DRM API required unprivileged clients to
        authenticate to a DRM-Master prior to getting GPU access. To avoid this
        step and to grant clients GPU access without authenticating, render
        nodes were introduced. Render nodes solely serve render clients, that
        is, no modesetting or privileged ioctls can be issued on render nodes.
        Only non-global rendering commands are allowed. If a driver supports
3365
        render nodes, it must advertise it via the DRIVER_RENDER
3366 3367 3368 3369 3370 3371
        DRM driver capability. If not supported, the primary node must be used
        for render clients together with the legacy drmAuth authentication
        procedure.
      </para>
      <para>
        If a driver advertises render node support, DRM core will create a
3372
        separate render node called renderD&lt;num&gt;. There will
3373
        be one render node per device. No ioctls except  PRIME-related ioctls
3374
        will be allowed on this node. Especially GEM_OPEN will be
3375 3376 3377 3378
        explicitly prohibited. Render nodes are designed to avoid the
        buffer-leaks, which occur if clients guess the flink names or mmap
        offsets on the legacy interface. Additionally to this basic interface,
        drivers must mark their driver-dependent render-only ioctls as
3379
        DRM_RENDER_ALLOW so render clients can use them. Driver
3380 3381 3382 3383 3384 3385 3386 3387 3388 3389 3390 3391 3392 3393 3394 3395 3396 3397 3398 3399 3400 3401 3402 3403
        authors must be careful not to allow any privileged ioctls on render
        nodes.
      </para>
      <para>
        With render nodes, user-space can now control access to the render node
        via basic file-system access-modes. A running graphics server which
        authenticates clients on the privileged primary/legacy node is no longer
        required. Instead, a client can open the render node and is immediately
        granted GPU access. Communication between clients (or servers) is done
        via PRIME. FLINK from render node to legacy node is not supported. New
        clients must not use the insecure FLINK interface.
      </para>
      <para>
        Besides dropping all modeset/global ioctls, render nodes also drop the
        DRM-Master concept. There is no reason to associate render clients with
        a DRM-Master as they are independent of any graphics server. Besides,
        they must work without any running master, anyway.
        Drivers must be able to run without a master object if they support
        render nodes. If, on the other hand, a driver requires shared state
        between clients which is visible to user-space and accessible beyond
        open-file boundaries, they cannot support render nodes.
      </para>
    </sect1>

3404 3405 3406 3407 3408 3409 3410 3411 3412 3413 3414 3415 3416 3417 3418 3419 3420 3421 3422 3423 3424
  <!-- External: vblank handling -->

    <sect1>
      <title>VBlank event handling</title>
      <para>
        The DRM core exposes two vertical blank related ioctls:
        <variablelist>
          <varlistentry>
            <term>DRM_IOCTL_WAIT_VBLANK</term>
            <listitem>
              <para>
                This takes a struct drm_wait_vblank structure as its argument,
                and it is used to block or request a signal when a specified
                vblank event occurs.
              </para>
            </listitem>
          </varlistentry>
          <varlistentry>
            <term>DRM_IOCTL_MODESET_CTL</term>
            <listitem>
              <para>
3425 3426 3427 3428 3429 3430
		This was only used for user-mode-settind drivers around
		modesetting changes to allow the kernel to update the vblank
		interrupt after mode setting, since on many devices the vertical
		blank counter is reset to 0 at some point during modeset. Modern
		drivers should not call this any more since with kernel mode
		setting it is a no-op.
3431 3432 3433 3434 3435 3436 3437
              </para>
            </listitem>
          </varlistentry>
        </variablelist>
      </para>
    </sect1>

3438
  </chapter>
3439 3440 3441
</part>
<part id="drmDrivers">
  <title>DRM Drivers</title>
3442

3443 3444
  <partintro>
    <para>
3445 3446
      This second part of the GPU Driver Developer's Guide documents driver
      code, implementation details and also all the driver-specific userspace
3447 3448 3449 3450 3451 3452
      interfaces. Especially since all hardware-acceleration interfaces to
      userspace are driver specific for efficiency and other reasons these
      interfaces can be rather substantial. Hence every driver has its own
      chapter.
    </para>
  </partintro>
3453

3454 3455
  <chapter id="drmI915">
    <title>drm/i915 Intel GFX Driver</title>
3456
    <para>
3457 3458 3459 3460
      The drm/i915 driver supports all (with the exception of some very early
      models) integrated GFX chipsets with both Intel display and rendering
      blocks. This excludes a set of SoC platforms with an SGX rendering unit,
      those have basic support through the gma500 drm driver.
3461
    </para>
3462 3463 3464 3465 3466 3467 3468 3469 3470 3471
    <sect1>
      <title>Core Driver Infrastructure</title>
      <para>
	This section covers core driver infrastructure used by both the display
	and the GEM parts of the driver.
      </para>
      <sect2>
        <title>Runtime Power Management</title>
!Pdrivers/gpu/drm/i915/intel_runtime_pm.c runtime pm
!Idrivers/gpu/drm/i915/intel_runtime_pm.c
3472
!Idrivers/gpu/drm/i915/intel_uncore.c
3473
      </sect2>
3474 3475 3476 3477 3478 3479 3480
      <sect2>
        <title>Interrupt Handling</title>
!Pdrivers/gpu/drm/i915/i915_irq.c interrupt handling
!Fdrivers/gpu/drm/i915/i915_irq.c intel_irq_init intel_irq_init_hw intel_hpd_init
!Fdrivers/gpu/drm/i915/i915_irq.c intel_runtime_pm_disable_interrupts
!Fdrivers/gpu/drm/i915/i915_irq.c intel_runtime_pm_enable_interrupts
      </sect2>
3481 3482 3483 3484 3485
      <sect2>
        <title>Intel GVT-g Guest Support(vGPU)</title>
!Pdrivers/gpu/drm/i915/i915_vgpu.c Intel GVT-g guest support
!Idrivers/gpu/drm/i915/i915_vgpu.c
      </sect2>
3486
    </sect1>
3487 3488 3489 3490 3491 3492 3493 3494 3495 3496 3497 3498 3499 3500 3501 3502
    <sect1>
      <title>Display Hardware Handling</title>
      <para>
        This section covers everything related to the display hardware including
        the mode setting infrastructure, plane, sprite and cursor handling and
        display, output probing and related topics.
      </para>
      <sect2>
        <title>Mode Setting Infrastructure</title>
        <para>
          The i915 driver is thus far the only DRM driver which doesn't use the
          common DRM helper code to implement mode setting sequences. Thus it
          has its own tailor-made infrastructure for executing a display
          configuration change.
        </para>
      </sect2>
3503 3504 3505 3506 3507
      <sect2>
        <title>Frontbuffer Tracking</title>
!Pdrivers/gpu/drm/i915/intel_frontbuffer.c frontbuffer tracking
!Idrivers/gpu/drm/i915/intel_frontbuffer.c
!Fdrivers/gpu/drm/i915/i915_gem.c i915_gem_track_fb
3508 3509 3510 3511 3512
      </sect2>
      <sect2>
        <title>Display FIFO Underrun Reporting</title>
!Pdrivers/gpu/drm/i915/intel_fifo_underrun.c fifo underrun handling
!Idrivers/gpu/drm/i915/intel_fifo_underrun.c
3513
      </sect2>
3514 3515 3516 3517 3518 3519 3520 3521 3522 3523
      <sect2>
        <title>Plane Configuration</title>
        <para>
	  This section covers plane configuration and composition with the
	  primary plane, sprites, cursors and overlays. This includes the
	  infrastructure to do atomic vsync'ed updates of all this state and
	  also tightly coupled topics like watermark setup and computation,
	  framebuffer compression and panel self refresh.
        </para>
      </sect2>
3524 3525 3526 3527 3528
      <sect2>
        <title>Atomic Plane Helpers</title>
!Pdrivers/gpu/drm/i915/intel_atomic_plane.c atomic plane helpers
!Idrivers/gpu/drm/i915/intel_atomic_plane.c
      </sect2>
3529 3530 3531 3532 3533 3534 3535 3536 3537
      <sect2>
        <title>Output Probing</title>
        <para>
	  This section covers output probing and related infrastructure like the
	  hotplug interrupt storm detection and mitigation code. Note that the
	  i915 driver still uses most of the common DRM helper code for output
	  probing, so those sections fully apply.
        </para>
      </sect2>
3538 3539 3540 3541 3542
      <sect2>
        <title>Hotplug</title>
!Pdrivers/gpu/drm/i915/intel_hotplug.c Hotplug
!Idrivers/gpu/drm/i915/intel_hotplug.c
      </sect2>
3543 3544 3545 3546
      <sect2>
	<title>High Definition Audio</title>
!Pdrivers/gpu/drm/i915/intel_audio.c High Definition Audio over HDMI and Display Port
!Idrivers/gpu/drm/i915/intel_audio.c
3547
!Iinclude/drm/i915_component.h
R
Rodrigo Vivi 已提交
3548 3549 3550 3551 3552
      </sect2>
      <sect2>
	<title>Panel Self Refresh PSR (PSR/SRD)</title>
!Pdrivers/gpu/drm/i915/intel_psr.c Panel Self Refresh (PSR/SRD)
!Idrivers/gpu/drm/i915/intel_psr.c
R
Rodrigo Vivi 已提交
3553 3554 3555 3556 3557
      </sect2>
      <sect2>
	<title>Frame Buffer Compression (FBC)</title>
!Pdrivers/gpu/drm/i915/intel_fbc.c Frame Buffer Compression (FBC)
!Idrivers/gpu/drm/i915/intel_fbc.c
3558 3559 3560 3561 3562 3563 3564 3565 3566 3567 3568
      </sect2>
      <sect2>
        <title>Display Refresh Rate Switching (DRRS)</title>
!Pdrivers/gpu/drm/i915/intel_dp.c Display Refresh Rate Switching (DRRS)
!Fdrivers/gpu/drm/i915/intel_dp.c intel_dp_set_drrs_state
!Fdrivers/gpu/drm/i915/intel_dp.c intel_edp_drrs_enable
!Fdrivers/gpu/drm/i915/intel_dp.c intel_edp_drrs_disable
!Fdrivers/gpu/drm/i915/intel_dp.c intel_edp_drrs_invalidate
!Fdrivers/gpu/drm/i915/intel_dp.c intel_edp_drrs_flush
!Fdrivers/gpu/drm/i915/intel_dp.c intel_dp_drrs_init

3569
      </sect2>
3570 3571 3572 3573
      <sect2>
        <title>DPIO</title>
!Pdrivers/gpu/drm/i915/i915_reg.h DPIO
      </sect2>
3574 3575 3576 3577 3578 3579

      <sect2>
       <title>CSR firmware support for DMC</title>
!Pdrivers/gpu/drm/i915/intel_csr.c csr support for dmc
!Idrivers/gpu/drm/i915/intel_csr.c
      </sect2>
3580
    </sect1>
3581

3582 3583 3584 3585 3586 3587
    <sect1>
      <title>Memory Management and Command Submission</title>
      <para>
	This sections covers all things related to the GEM implementation in the
	i915 driver.
      </para>
3588 3589 3590 3591
      <sect2>
        <title>Batchbuffer Parsing</title>
!Pdrivers/gpu/drm/i915/i915_cmd_parser.c batch buffer command parser
!Idrivers/gpu/drm/i915/i915_cmd_parser.c
3592 3593 3594 3595 3596
      </sect2>
      <sect2>
        <title>Batchbuffer Pools</title>
!Pdrivers/gpu/drm/i915/i915_gem_batch_pool.c batch pool
!Idrivers/gpu/drm/i915/i915_gem_batch_pool.c
3597
      </sect2>
3598 3599 3600 3601 3602
      <sect2>
        <title>Logical Rings, Logical Ring Contexts and Execlists</title>
!Pdrivers/gpu/drm/i915/intel_lrc.c Logical Rings, Logical Ring Contexts and Execlists
!Idrivers/gpu/drm/i915/intel_lrc.c
      </sect2>
3603 3604 3605 3606
      <sect2>
        <title>Global GTT views</title>
!Pdrivers/gpu/drm/i915/i915_gem_gtt.c Global GTT views
!Idrivers/gpu/drm/i915/i915_gem_gtt.c
D
Daniel Vetter 已提交
3607 3608
      </sect2>
      <sect2>
3609
        <title>GTT Fences and Swizzling</title>
D
Daniel Vetter 已提交
3610
!Idrivers/gpu/drm/i915/i915_gem_fence.c
3611 3612 3613 3614 3615 3616 3617 3618 3619 3620 3621 3622 3623
        <sect3>
          <title>Global GTT Fence Handling</title>
!Pdrivers/gpu/drm/i915/i915_gem_fence.c fence register handling
        </sect3>
        <sect3>
          <title>Hardware Tiling and Swizzling Details</title>
!Pdrivers/gpu/drm/i915/i915_gem_fence.c tiling swizzling details
        </sect3>
      </sect2>
      <sect2>
        <title>Object Tiling IOCTLs</title>
!Idrivers/gpu/drm/i915/i915_gem_tiling.c
!Pdrivers/gpu/drm/i915/i915_gem_tiling.c buffer object tiling
3624
      </sect2>
3625 3626 3627
      <sect2>
        <title>Buffer Object Eviction</title>
	<para>
3628
	  This section documents the interface functions for evicting buffer
3629 3630 3631 3632 3633 3634 3635
	  objects to make space available in the virtual gpu address spaces.
	  Note that this is mostly orthogonal to shrinking buffer objects
	  caches, which has the goal to make main memory (shared with the gpu
	  through the unified memory architecture) available.
	</para>
!Idrivers/gpu/drm/i915/i915_gem_evict.c
      </sect2>
3636 3637 3638 3639 3640 3641 3642 3643 3644 3645 3646
      <sect2>
        <title>Buffer Object Memory Shrinking</title>
	<para>
	  This section documents the interface function for shrinking memory
	  usage of buffer object caches. Shrinking is used to make main memory
	  available.  Note that this is mostly orthogonal to evicting buffer
	  objects, which has the goal to make space in gpu virtual address
	  spaces.
	</para>
!Idrivers/gpu/drm/i915/i915_gem_shrinker.c
      </sect2>
3647
    </sect1>
3648
    <sect1>
A
Alex Dai 已提交
3649
      <title>GuC</title>
3650
      <sect2>
A
Alex Dai 已提交
3651
        <title>GuC-specific firmware loader</title>
3652 3653 3654 3655
!Pdrivers/gpu/drm/i915/intel_guc_loader.c GuC-specific firmware loader
!Idrivers/gpu/drm/i915/intel_guc_loader.c
      </sect2>
      <sect2>
A
Alex Dai 已提交
3656 3657
        <title>GuC-based command submission</title>
!Pdrivers/gpu/drm/i915/i915_guc_submission.c GuC-based command submission
3658
!Idrivers/gpu/drm/i915/i915_guc_submission.c
3659
      </sect2>
A
Alex Dai 已提交
3660 3661 3662 3663
      <sect2>
        <title>GuC Firmware Layout</title>
!Pdrivers/gpu/drm/i915/intel_guc_fwif.h GuC Firmware Layout
      </sect2>
3664 3665
    </sect1>

3666 3667 3668 3669 3670 3671 3672 3673 3674 3675 3676 3677 3678 3679 3680 3681 3682 3683 3684 3685
    <sect1>
      <title> Tracing </title>
      <para>
    This sections covers all things related to the tracepoints implemented in
    the i915 driver.
      </para>
      <sect2>
        <title> i915_ppgtt_create and i915_ppgtt_release </title>
!Pdrivers/gpu/drm/i915/i915_trace.h i915_ppgtt_create and i915_ppgtt_release tracepoints
      </sect2>
      <sect2>
        <title> i915_context_create and i915_context_free </title>
!Pdrivers/gpu/drm/i915/i915_trace.h i915_context_create and i915_context_free tracepoints
      </sect2>
      <sect2>
        <title> switch_mm </title>
!Pdrivers/gpu/drm/i915/i915_trace.h switch_mm tracepoint
      </sect2>
    </sect1>

3686
  </chapter>
3687
!Cdrivers/gpu/drm/i915/i915_irq.c
3688
</part>
3689 3690 3691 3692 3693 3694 3695 3696 3697 3698 3699 3700 3701 3702 3703 3704 3705 3706 3707 3708 3709 3710 3711 3712 3713 3714 3715 3716 3717 3718 3719 3720 3721 3722 3723 3724 3725 3726 3727 3728 3729 3730 3731 3732 3733 3734

<part id="vga_switcheroo">
  <title>vga_switcheroo</title>
  <partintro>
!Pdrivers/gpu/vga/vga_switcheroo.c Overview
  </partintro>

  <chapter id="modes_of_use">
    <title>Modes of Use</title>
  <sect1>
    <title>Manual switching and manual power control</title>
!Pdrivers/gpu/vga/vga_switcheroo.c Manual switching and manual power control
  </sect1>
  <sect1>
    <title>Driver power control</title>
!Pdrivers/gpu/vga/vga_switcheroo.c Driver power control
  </sect1>
  </chapter>

  <chapter id="pubfunctions">
    <title>Public functions</title>
!Edrivers/gpu/vga/vga_switcheroo.c
  </chapter>

  <chapter id="pubstructures">
    <title>Public structures</title>
!Finclude/linux/vga_switcheroo.h vga_switcheroo_handler
!Finclude/linux/vga_switcheroo.h vga_switcheroo_client_ops
  </chapter>

  <chapter id="pubconstants">
    <title>Public constants</title>
!Finclude/linux/vga_switcheroo.h vga_switcheroo_client_id
!Finclude/linux/vga_switcheroo.h vga_switcheroo_state
  </chapter>

  <chapter id="privstructures">
    <title>Private structures</title>
!Fdrivers/gpu/vga/vga_switcheroo.c vgasr_priv
!Fdrivers/gpu/vga/vga_switcheroo.c vga_switcheroo_client
  </chapter>

!Cdrivers/gpu/vga/vga_switcheroo.c
!Cinclude/linux/vga_switcheroo.h
</part>

3735
</book>