This the beginning of an API for in-kernel clients.
First out is a way to get a framebuffer backed by a dumb buffer.

Only GEM drivers are supported.
The original idea of using an exported dma-buf was dropped because it
also creates an anonomous file descriptor which doesn't work when the
buffer is created from a kernel thread. The easy way out is to use
drm_driver.gem_prime_vmap to get the virtual address, which requires a
GEM object. This excludes the vmwgfx driver which is the only non-GEM
driver apart from the legacy ones. A solution for vmwgfx will have to be
worked out later if it wants to support the client API which it probably
will when we have a bootsplash client.
Suggested-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NNoralf Trønnes <noralf@tronnes.org>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20180703160354.59955-2-noralf@tronnes.org

Without this, we get link errors during randconfig build:

drivers/gpu/drm/vkms/vkms_drv.o:(.rodata+0xa0): undefined reference to `drm_atomic_helper_check'
drivers/gpu/drm/vkms/vkms_drv.o:(.rodata+0xa8): undefined reference to `drm_atomic_helper_commit'
drivers/gpu/drm/vkms/vkms_plane.o:(.rodata+0x0): undefined reference to `drm_atomic_helper_update_plane'
drivers/gpu/drm/vkms/vkms_plane.o:(.rodata+0x8): undefined reference to `drm_atomic_helper_disable_plane'
drivers/gpu/drm/vkms/vkms_plane.o:(.rodata+0x18): undefined reference to `drm_atomic_helper_plane_reset'
drivers/gpu/drm/vkms/vkms_plane.o:(.rodata+0x28): undefined reference to `drm_atomic_helper_plane_duplicate_state'
drivers/gpu/drm/vkms/vkms_plane.o:(.rodata+0x30): undefined reference to `drm_atomic_helper_plane_destroy_state'
drivers/gpu/drm/vkms/vkms_output.o:(.rodata+0x1c0): undefined reference to `drm_helper_probe_single_connector_modes'
drivers/gpu/drm/vkms/vkms_crtc.o:(.rodata+0x40): undefined reference to `drm_atomic_helper_crtc_reset'
drivers/gpu/drm/vkms/vkms_crtc.o:(.rodata+0x70): undefined reference to `drm_atomic_helper_set_config'
drivers/gpu/drm/vkms/vkms_crtc.o:(.rodata+0x78): undefined reference to `drm_atomic_helper_page_flip'
drivers/gpu/drm/vkms/vkms_crtc.o:(.rodata+0x90): undefined reference to `drm_atomic_helper_crtc_duplicate_state'
drivers/gpu/drm/vkms/vkms_crtc.o:(.rodata+0x98): undefined reference to `drm_atomic_helper_crtc_destroy_state'

Fixes: 854502fa ("drm/vkms: Add basic CRTC initialization")
Fixes: 1c7c5fd9 ("drm/vkms: Introduce basic VKMS driver")
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20180709154901.1989316-1-arnd@arndb.de

The transposer block is providing support for mem-to-mem composition,
which is exposed as a drm_writeback connector in DRM.

Add a driver to support this feature.
Signed-off-by: NBoris Brezillon <boris.brezillon@free-electrons.com>
Reviewed-by: NEric Anholt <eric@anholt.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20180703075022.15138-9-boris.brezillon@bootlin.com

Mimic what is done in drm_atomic_commit_tail() and call
drm_atomic_helper_fake_vblank() so that VBLANK events are faked
when the drm_crtc_state.no_vblank is true. Will be needed when we'll
add support for the transposer block.
Signed-off-by: NBoris Brezillon <boris.brezillon@bootlin.com>
Reviewed-by: NEric Anholt <eric@anholt.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20180703075022.15138-8-boris.brezillon@bootlin.com

Now that we have a way to fake VBLANK events when requested by the CRTC
hook it up to the generic commit_tail() helpers.
Signed-off-by: NBoris Brezillon <boris.brezillon@bootlin.com>
Reviewed-by: NLiviu Dudau <liviu.dudau@arm.com>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20180703075022.15138-7-boris.brezillon@bootlin.com

In some cases CRTCs are active but are not able to generating events, at
least not at every frame at it's expected to.
This is typically the case when the CRTC is feeding a writeback connector
that has no job queued. In this situation the CRTC is usually stopped
until a new job is queued, and this can lead to timeouts when part of
the pipeline is updated but no new jobs are queued to the active
writeback connector.

In order to solve that, we add a ->no_vblank flag to drm_crtc_state
and ask the CRTC drivers to set it to true when they know they're not
able to generate VBLANK events. The core drm_atomic_helper_fake_vblank()
helper can then be used to fake VBLANKs at commit time.
Signed-off-by: NBoris Brezillon <boris.brezillon@bootlin.com>
Reviewed-by: NLiviu Dudau <liviu.dudau@arm.com>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20180703075022.15138-6-boris.brezillon@bootlin.com

drm_atomic_helper_wait_for_vblanks() assumes the CRTC will continuously
generate VBLANK events and the vblank counter will keep increasing.
While this work for a regular pipeline, it doesn't when you have the
CRTC is feeding the transposer block, because this block works in
oneshot mode, and, by the time we reach
drm_atomic_helper_wait_for_vblanks() the only VBLANK event might have
already been sent and the VBLANK counter will stay unchanged, thus
triggering a timeout.

Luckily, we can replace the drm_atomic_helper_wait_for_vblanks() call
by drm_atomic_helper_wait_for_flip_done() because the only thing we
want to check when calling drm_atomic_helper_wait_for_vblanks() from
vc4_atomic_complete_commit() is that new FBs are in use and the old
ones can be safely released.
Signed-off-by: NBoris Brezillon <boris.brezillon@bootlin.com>
Reviewed-by: NLiviu Dudau <liviu.dudau@arm.com>
Reviewed-by: NEric Anholt <eric@anholt.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20180703075022.15138-5-boris.brezillon@bootlin.com

Not all writeback connector implementations might want to commit things
from the connector driver. Some, like the malidp driver, commit things
from their main commit_tail() function, and would rather not have to
implement a dummy hook for drm_connector_helper_funcs.atomic_commit().

Make this function optional and reflect this fact in the doc.
Signed-off-by: NBoris Brezillon <boris.brezillon@bootlin.com>
Acked-by: NLiviu Dudau <liviu.dudau@arm.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180703075022.15138-4-boris.brezillon@bootlin.com

Other atomic hooks are passed state objects, let's change this one to
be consistent.
Signed-off-by: NBoris Brezillon <boris.brezillon@bootlin.com>
Acked-by: NLiviu Dudau <liviu.dudau@arm.com>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20180703075022.15138-3-boris.brezillon@bootlin.com

Use container_of() instead of type casting so that it keeps working
even if base is moved inside the drm_writeback_connector struct.
Signed-off-by: NBoris Brezillon <boris.brezillon@bootlin.com>
Reviewed-by: NLiviu Dudau <liviu.dudau@arm.com>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20180703075022.15138-2-boris.brezillon@bootlin.com

Fix the bullet list declaration in the overview section.
Signed-off-by: NBoris Brezillon <boris.brezillon@bootlin.com>
Reported-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Fixes: 935774cd ("drm: Add writeback connector type")
Acked-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20180703174046.22396-1-boris.brezillon@bootlin.com

This reduces the amount of spam when you debug a CRC reading
program.
Signed-off-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
[mlankhorst: Change bool overflow to was_overflow (Ville)]
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180418125121.72081-1-maarten.lankhorst@linux.intel.com

Reset must be properly assert before deassert.
This is important if there is an early boot splash screen
before the kernel start up.
Signed-off-by: NYannick Fertre <yannick.fertre@st.com>
Reviewed-by: NPhilippe Cornu <philippe.cornu@st.com>
Tested-by: NPhilippe Cornu <philippe.cornu@st.com>
Signed-off-by: NBenjamin Gaignard <benjamin.gaignard@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/1530271355-5608-1-git-send-email-yannick.fertre@st.com

Filter the requested mode pixel clock frequency according
to the pad maximum supported frequency.
Signed-off-by: NYannick Fertre <yannick.fertre@st.com>
Reviewed-by: NPhilippe Cornu <philippe.cornu@st.com>
Tested-by: NPhilippe Cornu <philippe.cornu@st.com>
Signed-off-by: NBenjamin Gaignard <benjamin.gaignard@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/1530271342-5532-1-git-send-email-yannick.fertre@st.com

When dumping plane state print normalized zpos value as done for
the other plane state fields.
Signed-off-by: NBenjamin Gaignard <benjamin.gaignard@linaro.org>
Reviewed-by: NPhilippe Cornu <philippe.cornu@st.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180605135407.20214-2-benjamin.gaignard@linaro.org

Using += to set the bits in a mask looks funny. It works in this case
because we never set the same bit twice. But let's switch to |= to
make this look more regular.

Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180615170734.2774-1-ville.syrjala@linux.intel.comReviewed-by: NEric Anholt <eric@anholt.net>

Signed-off-by: NEric Anholt <eric@anholt.net>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20180703170515.6298-4-eric@anholt.netReviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Acked-by: NDaniel Vetter <daniel@ffwll.ch>

The dma-fence core as of commit 418cc6ca ("dma-fence: Make ->wait
callback optional") provides appropriate defaults for these methods.
Signed-off-by: NEric Anholt <eric@anholt.net>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20180703170515.6298-2-eric@anholt.netReviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Acked-by: NDaniel Vetter <daniel@ffwll.ch>

GTF-GLES2.gtf.GL.acos.acos_float_vert_xvary submits jobs that take 4
seconds at maximum resolution, but we still want to reset quickly if a
job is really hung.  Sample the CL's current address and the return
address (since we call into tile lists repeatedly) and if either has
changed then assume we've made progress.
Signed-off-by: NEric Anholt <eric@anholt.net>
Cc: Lucas Stach <l.stach@pengutronix.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20180703170515.6298-1-eric@anholt.netReviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Acked-by: NDaniel Vetter <daniel@ffwll.ch>

Instead of converting an errno into a vm_fault_t ourselves, use
vmf_insert_mixed() which returns a vm_fault_t directly.
Signed-off-by: NSouptick Joarder <jrdr.linux@gmail.com>
Signed-off-by: NEric Anholt <eric@anholt.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20180704145556.GA11036@jordon-HP-15-Notebook-PCReviewed-by: NMatthew Wilcox <willy@infradead.org>

malidp_pm_suspend_late checks if the runtime status is not suspended
and if so, invokes malidp_runtime_pm_suspend which disables the
display engine/core interrupts and the clocks. It sets the runtime status
as suspended.

The difference between suspend() and suspend_late() is as follows:-
1. suspend() makes the device quiescent. In our case, we invoke the DRM
helper which disables the CRTC. This would have invoked runtime pm
suspend but the system suspend process disables runtime pm.
2. suspend_late() It continues the suspend operations of the drm device
which was started by suspend(). In our case, it performs the same functionality
as runtime_suspend().

The complimentary functions are resume() and resume_early(). In the case of
resume_early(), we invoke malidp_runtime_pm_resume() which enables the clocks
and the interrupts. It sets the runtime status as active. If the device was
in runtime suspend mode before system suspend was called, pm_runtime_work()
will put the device back in runtime suspended mode( after the complete system
has been resumed).
Signed-off-by: NAyan Kumar Halder <ayan.halder@arm.com>
Acked-by: NLiviu Dudau <liviu.dudau@arm.com>
Signed-off-by: NLiviu Dudau <liviu.dudau@arm.com>

One needs to store the value of the OUTPUT_DEPTH that one has parsed from
device tree, so that it can be restored on system resume. This value is
set in the modeset function as this gets reset when the system suspends.
Signed-off-by: NAyan Kumar Halder <ayan.halder@arm.com>
Acked-by: NLiviu Dudau <liviu.dudau@arm.com>
Signed-off-by: NLiviu Dudau <liviu.dudau@arm.com>

Display and scaling engine interrupts need to be disabled when the
runtime pm invokes malidp_runtime_pm_suspend(). Conversely, they
need to be enabled in malidp_runtime_pm_resume().

This patch depends on:
https://lkml.org/lkml/2017/5/15/695Reported-by: NAlexandru-Cosmin Gheorghe <Alexandru-Cosmin.Gheorghe@arm.com>
Signed-off-by: NAlexandru-Cosmin Gheorghe <Alexandru-Cosmin.Gheorghe@arm.com>
Signed-off-by: NAyan Kumar Halder <ayan.halder@arm.com>
Acked-by: NLiviu Dudau <liviu.dudau@arm.com>
Signed-off-by: NLiviu Dudau <liviu.dudau@arm.com>

Malidp uses two interrupts ie 1. se_irq - used for memory writeback.
 and 2. de_irq - used for display output.
Extract the hardware initialization part from malidp interrupt registration
ie (malidp_de_irq_init()/ malidp_se_irq_init()) into a separate function
(ie malidp_de_irq_hw_init()/malidp_se_irq_hw_init())
which will be later invoked from runtime_pm_resume function when it needs
to re-enable the interrupts.
Signed-off-by: NAyan Kumar Halder <ayan.halder@arm.com>
Acked-by: NLiviu Dudau <liviu.dudau@arm.com>
Signed-off-by: NLiviu Dudau <liviu.dudau@arm.com>

Malidp uses two interrupts ie 1. se_irq - used for memory writeback.
 and 2. de_irq - used for display output.
'struct drm_device' is being replaced with 'struct malidp_hw_device'
as the function argument. The reason being the dependency of
malidp_de_irq_fini on 'struct drm_device' needs to be removed so as to
enable it to call from functions which receives 'struct malidp_hw_device'
as argument. Furthermore, there is no way to retrieve 'struct drm_device'
from 'struct malidp_hw_device'.
Signed-off-by: NAyan Kumar Halder <ayan.halder@arm.com>
Acked-by: NLiviu Dudau <liviu.dudau@arm.com>
Signed-off-by: NLiviu Dudau <liviu.dudau@arm.com>

Status register contains a lot of bits for reporting internal errors
inside Mali DP. Currently, we just silently ignore all of the errors,
that doesn't help when we are investigating different bugs, especially
on the FPGA models which have a lot of constraints, so we could easily
end up in AXI or underrun errors.

Add a new file called debug that contains an aggregate of the
errors reported by the Mali DP hardware.

E.g:
[root@alarm ~]# cat /sys/kernel/debug/dri/1/debug
[DE] num_errors : 167
[DE] last_error_status  : 0x00000001
[DE] last_error_vblank : 385
[SE] num_errors : 3
[SE] last_error_status  : 0x00e23001
[SE] last_error_vblank : 201

Changes since v2:
- Add lock to protect the errors stats.
- Add possibility to reset the error stats by writing anything to the
  debug file.
Signed-off-by: NAlexandru Gheorghe <alexandru-cosmin.gheorghe@arm.com>
Acked-by: NLiviu Dudau <liviu.dudau@arm.com>
Signed-off-by: NLiviu Dudau <liviu.dudau@arm.com>

Mali DP500 operates in continuous writeback mode (writes frame content
until stopped) and it needs special handling in order to behave like
a one-shot writeback engine. The original state machine added for DP500
was a bit fragile, as it did not handle correctly cases where a new
atomic commit was in progress when the SE IRQ happens and it would
commit some partial updates.

Improve the handling by adding a parameter to the set_config_valid()
function to clear the config valid bit in hardware before starting a
new commit and by introducing a MW_RESTART state in the writeback
state machine to cater for the case where a new writeback commit
gets submitted while the last one is still being active.
Reported-by: NBrian Starkey <brian.starkey@arm.com>
Reviewed-by: NBrian Starkey <brian.starkey@arm.com>
Signed-off-by: NLiviu Dudau <liviu.dudau@arm.com>

Mali-DP has a memory writeback engine which can be used to write the
composition result to a memory buffer. Expose this functionality as a
DRM writeback connector on supported hardware.

Changes since v1:
 Daniel Vetter:
 - Don't require a modeset when writeback routing changes
 - Make writeback connector always disconnected

Changes since v2:
 - Rebase onto new drm_writeback_connector
 - Add reset callback, allocating subclassed state
 Daniel Vetter:
 - Squash out-fence support into this commit
 Gustavo Padovan:
 - Don't signal fence directly from driver (and drop malidp_mw_job)

Changes since v3:
 - Modifications to fit with Mali-DP commit tail changes
Signed-off-by: NBrian Starkey <brian.starkey@arm.com>
[rebased and fixed conflicts]
Signed-off-by: NMihail Atanassov <mihail.atanassov@arm.com>
Signed-off-by: NLiviu Dudau <liviu.dudau@arm.com>

Annotate the pixel format matrix for DP500 with the memory-write flag
for formats that are supported by the SE memwrite engine.
Reviewed-by: NBrian Starkey <brian.starkey@arm.com>
Signed-off-by: NLiviu Dudau <liviu.dudau@arm.com>

Mali DP500 behaves differently from the rest of the Mali DP IP,
in that it does not have a one-shot mode and keeps writing the
content of the current frame to the provided memory area until
stopped. As a way of emulating the one-shot behaviour, we are
going to use the CVAL interrupt that is being raised at the
start of each frame, during prefetch phase, to act as End-of-Write
signal, but with a twist: we are going to disable the memory
write engine right after we're notified that it has been enabled,
using the knowledge that the bit controlling the enabling will
only be acted upon on the next vblank/prefetch.

CVAL interrupt will fire durint the next prefetch phase every time
the global CVAL bit gets set, so we need a state byte to track
the memory write enabling. We also need to pay attention during the
disabling of the memory write engine as that requires the CVAL bit
to be set in the control register, but we don't want to do that
during an atomic commit, as it will write into the hardware a partial
state.
Reviewed-by: NBrian Starkey <brian.starkey@arm.com>
Signed-off-by: NLiviu Dudau <liviu.dudau@arm.com>

Add a layer bit for the SE memory-write, and add it to the pixel format
matrix for DP550/DP650.
Signed-off-by: NBrian Starkey <brian.starkey@arm.com>
[rebased and fixed conflicts]
Signed-off-by: NMihail Atanassov <mihail.atanassov@arm.com>
Signed-off-by: NLiviu Dudau <liviu.dudau@arm.com>

Mali-DP display processors are able to write the composition result to a
memory buffer via the SE.

Add entry points in the HAL for enabling/disabling this feature, and
implement support for it on DP650 and DP550. DP500 acts differently and
so is omitted from this change.

Changes since v3:
 - Fix missing vsync interrupt for DP550
Signed-off-by: NLiviu Dudau <Liviu.Dudau@arm.com>
Signed-off-by: NBrian Starkey <brian.starkey@arm.com>
[rebased and fixed conflicts]
Signed-off-by: NMihail Atanassov <mihail.atanassov@arm.com>

Use drm_connector_has_possible_encoder() for checking
whether the encoder has an associated connector.

v2: Replace the drm_for_each_connector_encoder_ids() loop
    with a simple drm_connector_has_possible_encoder() call

Cc: Jyri Sarha <jsarha@ti.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180628131315.14156-10-ville.syrjala@linux.intel.comReviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Acked-by: NJyri Sarha <jsarha@ti.com>

Use drm_connector_has_possible_encoder() for checking
whether the encoder has an associated connector.

v2: Replace the drm_for_each_connector_encoder_ids() loop
    with a simple drm_connector_has_possible_encoder() call

Cc: Rob Clark <robdclark@gmail.com>
Cc: linux-arm-msm@vger.kernel.org
Cc: freedreno@lists.freedesktop.org
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180628131315.14156-9-ville.syrjala@linux.intel.comReviewed-by: NAlex Deucher <alexander.deucher@amd.com>

Add a small helper for checking whether a connector and
encoder are associated with each other.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180628131315.14156-8-ville.syrjala@linux.intel.comReviewed-by: NAlex Deucher <alexander.deucher@amd.com>

Use drm_connector_for_each_possible_encoder() for iterating
connector->encoder_ids[]. A bit more convenient not having
to deal with the implementation details.

v2: Replace drm_for_each_connector_encoder_ids() with
    drm_connector_for_each_possible_encoder() (Daniel)

Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: "Christian König" <christian.koenig@amd.com>
Cc: "David (ChunMing) Zhou" <David1.Zhou@amd.com>
Cc: Harry Wentland <harry.wentland@amd.com>
Cc: amd-gfx@lists.freedesktop.org
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180628131315.14156-7-ville.syrjala@linux.intel.com

Use drm_connector_for_each_possible_encoder() for iterating
connector->encoder_ids[]. A bit more convenient not having
to deal with the implementation details.

v2: Replace drm_for_each_connector_encoder_ids() with
    drm_connector_for_each_possible_encoder() (Daniel)
v3: Initialize nv_encoder to NULL to shut up gcc/smatch

Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: nouveau@lists.freedesktop.org
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180702152927.13351-1-ville.syrjala@linux.intel.com

Use drm_connector_for_each_possible_encoder() for iterating
connector->encoder_ids[]. A bit more convenient not having
to deal with the implementation details.

v2: Replace drm_for_each_connector_encoder_ids() with
    drm_connector_for_each_possible_encoder() (Daniel)

Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: "Christian König" <christian.koenig@amd.com>
Cc: "David (ChunMing) Zhou" <David1.Zhou@amd.com>
Cc: Harry Wentland <harry.wentland@amd.com>
Cc: amd-gfx@lists.freedesktop.org
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180628131315.14156-5-ville.syrjala@linux.intel.com

Add a convenience macro for iterating connector->encoder_ids[].
Isolates the users from the implementation details.

Note that we don't seem to pass the file_priv down to drm_encoder_find()
because encoders apparently don't get leased. No idea why
drm_encoder_finc() even takes the file_priv actually.

Also use ARRAY_SIZE() when populating the array to avoid spreading
knowledge about the array size all over.

v2: Hide the drm_encoder_find() in the macro, and
    rename the macro appropriately (Daniel)
v3: Fix kernel docs (Daniel)

Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180628131315.14156-4-ville.syrjala@linux.intel.comReviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

With the fb-helper no longer relying on the non-atomic .best_encoder()
we can eliminate the hook from the MST encoder.

Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180628131315.14156-3-ville.syrjala@linux.intel.com