Documentation/gpu: split up the gpu documentation

Make the gpu documentation easier to manage by splitting to separate
files. Again, this is just the split, no real edits.
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/bd2b599b5105c28c8f05923005e6cc9b7efa7fc1.1466506505.git.jani.nikula@intel.com

Documentation/gpu/drm-uapi.rst

+Userland interfaces
+===================
+
+The DRM core exports several interfaces to applications, generally
+intended to be used through corresponding libdrm wrapper functions. In
+addition, drivers export device-specific interfaces for use by userspace
+drivers & device-aware applications through ioctls and sysfs files.
+
+External interfaces include: memory mapping, context management, DMA
+operations, AGP management, vblank control, fence management, memory
+management, and output management.
+
+Cover generic ioctls and sysfs layout here. We only need high-level
+info, since man pages should cover the rest.
+
+Render nodes
+------------
+
+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
+and called card<num>. Additionally, a currently unused control node,
+called controlD<num> is also 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.
+
+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
+render nodes, it must advertise it via the DRIVER_RENDER DRM driver
+capability. If not supported, the primary node must be used for render
+clients together with the legacy drmAuth authentication procedure.
+
+If a driver advertises render node support, DRM core will create a
+separate render node called renderD<num>. There will be one render node
+per device. No ioctls except PRIME-related ioctls will be allowed on
+this node. Especially GEM_OPEN will be 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 DRM_RENDER_ALLOW so render
+clients can use them. Driver authors must be careful not to allow any
+privileged ioctls on render nodes.
+
+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.
+
+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.
+
+VBlank event handling
+---------------------
+
+The DRM core exposes two vertical blank related ioctls:
+
+DRM_IOCTL_WAIT_VBLANK
+    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.
+
+DRM_IOCTL_MODESET_CTL
+    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.
+
+This second part of the GPU Driver Developer's Guide documents driver
+code, implementation details and also all the driver-specific userspace
+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.

Documentation/gpu/i915.rst

+drm/i915 Intel GFX Driver
+=========================
+
+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.
+
+Core Driver Infrastructure
+--------------------------
+
+This section covers core driver infrastructure used by both the display
+and the GEM parts of the driver.
+
+Runtime Power Management
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. kernel-doc:: drivers/gpu/drm/i915/intel_runtime_pm.c
+   :doc: runtime pm
+
+.. kernel-doc:: drivers/gpu/drm/i915/intel_runtime_pm.c
+   :internal:
+
+.. kernel-doc:: drivers/gpu/drm/i915/intel_uncore.c
+   :internal:
+
+Interrupt Handling
+~~~~~~~~~~~~~~~~~~
+
+.. kernel-doc:: drivers/gpu/drm/i915/i915_irq.c
+   :doc: interrupt handling
+
+.. kernel-doc:: drivers/gpu/drm/i915/i915_irq.c
+   :functions: intel_irq_init intel_irq_init_hw intel_hpd_init
+
+.. kernel-doc:: drivers/gpu/drm/i915/i915_irq.c
+   :functions: intel_runtime_pm_disable_interrupts
+
+.. kernel-doc:: drivers/gpu/drm/i915/i915_irq.c
+   :functions: intel_runtime_pm_enable_interrupts
+
+Intel GVT-g Guest Support(vGPU)
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. kernel-doc:: drivers/gpu/drm/i915/i915_vgpu.c
+   :doc: Intel GVT-g guest support
+
+.. kernel-doc:: drivers/gpu/drm/i915/i915_vgpu.c
+   :internal:
+
+Display Hardware Handling
+-------------------------
+
+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.
+
+Mode Setting Infrastructure
+~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+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.
+
+Frontbuffer Tracking
+~~~~~~~~~~~~~~~~~~~~
+
+.. kernel-doc:: drivers/gpu/drm/i915/intel_frontbuffer.c
+   :doc: frontbuffer tracking
+
+.. kernel-doc:: drivers/gpu/drm/i915/intel_frontbuffer.c
+   :internal:
+
+.. kernel-doc:: drivers/gpu/drm/i915/i915_gem.c
+   :functions: i915_gem_track_fb
+
+Display FIFO Underrun Reporting
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. kernel-doc:: drivers/gpu/drm/i915/intel_fifo_underrun.c
+   :doc: fifo underrun handling
+
+.. kernel-doc:: drivers/gpu/drm/i915/intel_fifo_underrun.c
+   :internal:
+
+Plane Configuration
+~~~~~~~~~~~~~~~~~~~
+
+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.
+
+Atomic Plane Helpers
+~~~~~~~~~~~~~~~~~~~~
+
+.. kernel-doc:: drivers/gpu/drm/i915/intel_atomic_plane.c
+   :doc: atomic plane helpers
+
+.. kernel-doc:: drivers/gpu/drm/i915/intel_atomic_plane.c
+   :internal:
+
+Output Probing
+~~~~~~~~~~~~~~
+
+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.
+
+Hotplug
+~~~~~~~
+
+.. kernel-doc:: drivers/gpu/drm/i915/intel_hotplug.c
+   :doc: Hotplug
+
+.. kernel-doc:: drivers/gpu/drm/i915/intel_hotplug.c
+   :internal:
+
+High Definition Audio
+~~~~~~~~~~~~~~~~~~~~~
+
+.. kernel-doc:: drivers/gpu/drm/i915/intel_audio.c
+   :doc: High Definition Audio over HDMI and Display Port
+
+.. kernel-doc:: drivers/gpu/drm/i915/intel_audio.c
+   :internal:
+
+.. kernel-doc:: include/drm/i915_component.h
+   :internal:
+
+Panel Self Refresh PSR (PSR/SRD)
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. kernel-doc:: drivers/gpu/drm/i915/intel_psr.c
+   :doc: Panel Self Refresh (PSR/SRD)
+
+.. kernel-doc:: drivers/gpu/drm/i915/intel_psr.c
+   :internal:
+
+Frame Buffer Compression (FBC)
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. kernel-doc:: drivers/gpu/drm/i915/intel_fbc.c
+   :doc: Frame Buffer Compression (FBC)
+
+.. kernel-doc:: drivers/gpu/drm/i915/intel_fbc.c
+   :internal:
+
+Display Refresh Rate Switching (DRRS)
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. kernel-doc:: drivers/gpu/drm/i915/intel_dp.c
+   :doc: Display Refresh Rate Switching (DRRS)
+
+.. kernel-doc:: drivers/gpu/drm/i915/intel_dp.c
+   :functions: intel_dp_set_drrs_state
+
+.. kernel-doc:: drivers/gpu/drm/i915/intel_dp.c
+   :functions: intel_edp_drrs_enable
+
+.. kernel-doc:: drivers/gpu/drm/i915/intel_dp.c
+   :functions: intel_edp_drrs_disable
+
+.. kernel-doc:: drivers/gpu/drm/i915/intel_dp.c
+   :functions: intel_edp_drrs_invalidate
+
+.. kernel-doc:: drivers/gpu/drm/i915/intel_dp.c
+   :functions: intel_edp_drrs_flush
+
+.. kernel-doc:: drivers/gpu/drm/i915/intel_dp.c
+   :functions: intel_dp_drrs_init
+
+DPIO
+~~~~
+
+.. kernel-doc:: drivers/gpu/drm/i915/i915_reg.h
+   :doc: DPIO
+
+CSR firmware support for DMC
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. kernel-doc:: drivers/gpu/drm/i915/intel_csr.c
+   :doc: csr support for dmc
+
+.. kernel-doc:: drivers/gpu/drm/i915/intel_csr.c
+   :internal:
+
+Video BIOS Table (VBT)
+~~~~~~~~~~~~~~~~~~~~~~
+
+.. kernel-doc:: drivers/gpu/drm/i915/intel_bios.c
+   :doc: Video BIOS Table (VBT)
+
+.. kernel-doc:: drivers/gpu/drm/i915/intel_bios.c
+   :internal:
+
+.. kernel-doc:: drivers/gpu/drm/i915/intel_vbt_defs.h
+   :internal:
+
+Memory Management and Command Submission
+----------------------------------------
+
+This sections covers all things related to the GEM implementation in the
+i915 driver.
+
+Batchbuffer Parsing
+~~~~~~~~~~~~~~~~~~~
+
+.. kernel-doc:: drivers/gpu/drm/i915/i915_cmd_parser.c
+   :doc: batch buffer command parser
+
+.. kernel-doc:: drivers/gpu/drm/i915/i915_cmd_parser.c
+   :internal:
+
+Batchbuffer Pools
+~~~~~~~~~~~~~~~~~
+
+.. kernel-doc:: drivers/gpu/drm/i915/i915_gem_batch_pool.c
+   :doc: batch pool
+
+.. kernel-doc:: drivers/gpu/drm/i915/i915_gem_batch_pool.c
+   :internal:
+
+Logical Rings, Logical Ring Contexts and Execlists
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. kernel-doc:: drivers/gpu/drm/i915/intel_lrc.c
+   :doc: Logical Rings, Logical Ring Contexts and Execlists
+
+.. kernel-doc:: drivers/gpu/drm/i915/intel_lrc.c
+   :internal:
+
+Global GTT views
+~~~~~~~~~~~~~~~~
+
+.. kernel-doc:: drivers/gpu/drm/i915/i915_gem_gtt.c
+   :doc: Global GTT views
+
+.. kernel-doc:: drivers/gpu/drm/i915/i915_gem_gtt.c
+   :internal:
+
+GTT Fences and Swizzling
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. kernel-doc:: drivers/gpu/drm/i915/i915_gem_fence.c
+   :internal:
+
+Global GTT Fence Handling
+^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. kernel-doc:: drivers/gpu/drm/i915/i915_gem_fence.c
+   :doc: fence register handling
+
+Hardware Tiling and Swizzling Details
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. kernel-doc:: drivers/gpu/drm/i915/i915_gem_fence.c
+   :doc: tiling swizzling details
+
+Object Tiling IOCTLs
+~~~~~~~~~~~~~~~~~~~~
+
+.. kernel-doc:: drivers/gpu/drm/i915/i915_gem_tiling.c
+   :internal:
+
+.. kernel-doc:: drivers/gpu/drm/i915/i915_gem_tiling.c
+   :doc: buffer object tiling
+
+Buffer Object Eviction
+~~~~~~~~~~~~~~~~~~~~~~
+
+This section documents the interface functions for evicting buffer
+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.
+
+.. kernel-doc:: drivers/gpu/drm/i915/i915_gem_evict.c
+   :internal:
+
+Buffer Object Memory Shrinking
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+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.
+
+.. kernel-doc:: drivers/gpu/drm/i915/i915_gem_shrinker.c
+   :internal:
+
+GuC
+---
+
+GuC-specific firmware loader
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. kernel-doc:: drivers/gpu/drm/i915/intel_guc_loader.c
+   :doc: GuC-specific firmware loader
+
+.. kernel-doc:: drivers/gpu/drm/i915/intel_guc_loader.c
+   :internal:
+
+GuC-based command submission
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. kernel-doc:: drivers/gpu/drm/i915/i915_guc_submission.c
+   :doc: GuC-based command submission
+
+.. kernel-doc:: drivers/gpu/drm/i915/i915_guc_submission.c
+   :internal:
+
+GuC Firmware Layout
+~~~~~~~~~~~~~~~~~~~
+
+.. kernel-doc:: drivers/gpu/drm/i915/intel_guc_fwif.h
+   :doc: GuC Firmware Layout
+
+Tracing
+-------
+
+This sections covers all things related to the tracepoints implemented
+in the i915 driver.
+
+i915_ppgtt_create and i915_ppgtt_release
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. kernel-doc:: drivers/gpu/drm/i915/i915_trace.h
+   :doc: i915_ppgtt_create and i915_ppgtt_release tracepoints
+
+i915_context_create and i915_context_free
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. kernel-doc:: drivers/gpu/drm/i915/i915_trace.h
+   :doc: i915_context_create and i915_context_free tracepoints
+
+switch_mm
+~~~~~~~~~~
+
+.. kernel-doc:: drivers/gpu/drm/i915/i915_trace.h
+   :doc: switch_mm tracepoint
+
+.. WARNING: DOCPROC directive not supported: !Cdrivers/gpu/drm/i915/i915_irq.c

Documentation/gpu/introduction.rst

+Introduction
+============
+
+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 drivers in the kernel may
+make use of DRM functions to make tasks like memory management,
+interrupt handling and DMA easier, and provide a uniform interface to
+applications.
+
+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.
+
+[Insert diagram of typical DRM stack here]
+
+Style Guidelines
+----------------
+
+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, &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 ->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.
+
+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.
+``WARN_ON(!mutex_is_locked(...));``. 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.
+
+Functions which have a non-\ ``void`` 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.

Documentation/gpu/vga-switcheroo.rst

+==============
+VGA Switcheroo
+==============
+
+.. kernel-doc:: drivers/gpu/vga/vga_switcheroo.c
+   :doc: Overview
+
+Modes of Use
+============
+
+Manual switching and manual power control
+-----------------------------------------
+
+.. kernel-doc:: drivers/gpu/vga/vga_switcheroo.c
+   :doc: Manual switching and manual power control
+
+Driver power control
+--------------------
+
+.. kernel-doc:: drivers/gpu/vga/vga_switcheroo.c
+   :doc: Driver power control
+
+API
+===
+
+Public functions
+----------------
+
+.. kernel-doc:: drivers/gpu/vga/vga_switcheroo.c
+   :export:
+
+Public structures
+-----------------
+
+.. kernel-doc:: include/linux/vga_switcheroo.h
+   :functions: vga_switcheroo_handler
+
+.. kernel-doc:: include/linux/vga_switcheroo.h
+   :functions: vga_switcheroo_client_ops
+
+Public constants
+----------------
+
+.. kernel-doc:: include/linux/vga_switcheroo.h
+   :functions: vga_switcheroo_handler_flags_t
+
+.. kernel-doc:: include/linux/vga_switcheroo.h
+   :functions: vga_switcheroo_client_id
+
+.. kernel-doc:: include/linux/vga_switcheroo.h
+   :functions: vga_switcheroo_state
+
+Private structures
+------------------
+
+.. kernel-doc:: drivers/gpu/vga/vga_switcheroo.c
+   :functions: vgasr_priv
+
+.. kernel-doc:: drivers/gpu/vga/vga_switcheroo.c
+   :functions: vga_switcheroo_client
+
+Handlers
+========
+
+apple-gmux Handler
+------------------
+
+.. kernel-doc:: drivers/platform/x86/apple-gmux.c
+   :doc: Overview
+
+.. kernel-doc:: drivers/platform/x86/apple-gmux.c
+   :doc: Interrupt
+
+Graphics mux
+~~~~~~~~~~~~
+
+.. kernel-doc:: drivers/platform/x86/apple-gmux.c
+   :doc: Graphics mux
+
+Power control
+~~~~~~~~~~~~~
+
+.. kernel-doc:: drivers/platform/x86/apple-gmux.c
+   :doc: Power control
+
+Backlight control
+~~~~~~~~~~~~~~~~~
+
+.. kernel-doc:: drivers/platform/x86/apple-gmux.c
+   :doc: Backlight control
+
+Public functions
+~~~~~~~~~~~~~~~~
+
+.. kernel-doc:: include/linux/apple-gmux.h
+   :internal:
+
+.. WARNING: DOCPROC directive not supported: !Cdrivers/gpu/vga/vga_switcheroo.c
+
+.. WARNING: DOCPROC directive not supported: !Cinclude/linux/vga_switcheroo.h
+
+.. WARNING: DOCPROC directive not supported: !Cdrivers/platform/x86/apple-gmux.c