This has been unused since commit 44b460cf ("drm: imx: remove struct
imx_drm_crtc and imx_drm_crtc_helper_funcs")
Signed-off-by: NLeonard Crestez <leonard.crestez@nxp.com>
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>

This patch unifies the naming of DRM functions for reference counting
of struct drm_device. The resulting code is more aligned with the rest
of the Linux kernel interfaces.
Signed-off-by: NThomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>

This adds FB modifier support for the Vivante single buffer tiled formats,
when the PRG/PRE engines are present.
Signed-off-by: NLucas Stach <l.stach@pengutronix.de>
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>

Use drm_fb_cma_fbdev_init() and drm_fb_cma_fbdev_fini() which relies on
the fact that drm_device holds a pointer to the drm_fb_helper structure.
This means that the driver doesn't have to keep track of that.
Also use the drm_fb_helper functions directly.

Cc: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: NNoralf Trønnes <noralf@tronnes.org>
Acked-by: NPhilipp Zabel <p.zabel@pengutronix.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20171115142001.45358-8-noralf@tronnes.org

drm_atomic_helper_wait_for_vblanks will go away in the future.

The new drm_atomic_helper_setup_commit in 4.15 expects that blocking commits
have completed flipping before the commit_tail returns. This must be ensured
by calling wait_for_vblanks or wait_for_flip_done, where flip_done might do
a less agressive wait, which is fine for imx-drm.

Fixes: 080de2e5 (drm/atomic: Check for busy planes/connectors before
                     setting the commit)
Signed-off-by: NLucas Stach <l.stach@pengutronix.de>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>

drm_fb_cma_create() and drm_fb_cma_prepare_fb() are just wrappers now,
use drm_gem_fb_create() and drm_gem_fb_prepare_fb() directly.

Cc: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: NNoralf Trønnes <noralf@tronnes.org>
Acked-by: NPhilipp Zabel <p.zabel@pengutronix.de>
Link: https://patchwork.freedesktop.org/patch/msgid/1502631125-13557-11-git-send-email-noralf@tronnes.org

This driver can use the drm_driver.dumb_destroy and
drm_driver.dumb_map_offset defaults, so no need to set them.

Cc: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: NNoralf Trønnes <noralf@tronnes.org>
Acked-by: NPhilipp Zabel <p.zabel@pengutronix.de>
Link: https://patchwork.freedesktop.org/patch/msgid/1500837417-40580-10-git-send-email-noralf@tronnes.org

for_each_obj_in_state is about to be removed, so use the new atomic
iterator macros.
Signed-off-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Philipp Zabel <p.zabel@pengutronix.de>
Link: http://patchwork.freedesktop.org/patch/msgid/20170712081344.25495-13-maarten.lankhorst@linux.intel.comReviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: NPhilipp Zabel <p.zabel@pengutronix.de>
Tested-by: NPhilipp Zabel <p.zabel@pengutronix.de>

It's only done in the driver load error path, where vblanks don't need
to be quiescent anyway. And that's all drm_vblank_cleanup does, since
the core will release the vblank allocations on its own already. So
drop it.

Cc: Philipp Zabel <p.zabel@pengutronix.de>
Acked-by: NPhilipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170524145212.27837-24-daniel.vetter@ffwll.ch

While it is possible to hook other CRTC implementations into imx-drm
in practice there are none yet and the option to disable ipuv3-crtc
support has been hidden for a long time.

Now that the imx-drm-core has learned to deal with some of the
specifics of IPUv3 there is a cyclic dependency between both parts.
To get rid of this and to decimate the Kconfig maze a bit, simply
merge both parts into one module.
Signed-off-by: NLucas Stach <l.stach@pengutronix.de>
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>

No one is using the structure imx_drm_component, so let's remove the
definition to save several lines.
Signed-off-by: NLiu Ying <gnuiyl@gmail.com>
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>

Allow the planes to use the PRG/PRE units as linear prefetchers when
possible. This improves DRAM efficiency a bit and reduces the chance
for display underflow when the memory subsystem is under load.

This does not yet support scanning out tiled buffers directly, as this
needs more work, but it already wires up the basic interaction between
imx-drm, the IPUv3 driver and the PRG and PRE drivers.
Signed-off-by: NLucas Stach <l.stach@pengutronix.de>
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>

The DP (display processor) channel disable code tried to busy wait for
the DP sync flow end interrupt status bit when disabling the partial
plane without a full modeset. That never worked reliably, and it was
disabled completely by the recent "gpu: ipu-v3: remove IRQ dance on DC
channel disable" patch, causing ipu_wait_interrupt to always time out
after 50 ms, which in turn would trigger a timeout in
drm_atomic_helper_wait_for_vblanks.

This patch changes ipu_plane_atomic_disable to only queue a DP channel
register update at the next frame boundary and set a flag, which can be
done without any waiting whatsoever. The imx_drm_atomic_commit_tail then
calls a new ipu_plane_disable_deferred function that does the actual
IDMAC teardown of the planes that are flagged for deferred disabling,
after waiting for the vblank.
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: NLucas Stach <l.stach@pengutronix.de>

drm_atomic_helper_cleanup_planes only calls the cleanup_fb plane
helpers, which we don't implement as a CMA framebuffer based driver.
There is no reason to wait for vblanks in commit_tail only to do nothing
afterwards.
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: NLucas Stach <l.stach@pengutronix.de>

Less code ftw.

This converts all drivers except the tinydrm helper module. That one
needs more work, since it gets the THIS_MODULE reference from
tinydrm.ko instead of the actual driver module like it should.
Probably needs a similar trick like I used here with generating the
entire struct with a macro.

Cc: Noralf Trønnes <noralf@tronnes.org>
Reviewed-by: NSean Paul <seanpaul@chromium.org>
Reviewed-by: NLiviu Dudau <Liviu.Dudau@arm.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170308141257.12119-24-daniel.vetter@ffwll.ch

There is no reason to limit framebuffer size to 64x64 pixels at a
minimum on creation. The actual scanout limitations (width >= 13 for the
base plane and height >= 2) are checked in atomic_check.
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: NLucas Stach <l.stach@pengutronix.de>

The drm_mode_config helper private field points to a structure of
function pointers that don't need to be modified at runtime. Make it
const.
Signed-off-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: NGabriel Krisman Bertazi <krisman@collabora.co.uk>
Acked-by: NBrian Starkey <brian.starkey@arm.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20170102091613.6310-1-laurent.pinchart@ideasonboard.com

With the vblank hooks in struct drm_crtc_funcs, we do not need to
maintain the CRTC specific vblank callbacks with struct
imx_drm_crtc_helper_funcs any more.  By moving the stuff that we
currently do in imx_drm_add_crtc(), like of_node setting and
drm_crtc_helper_add()/drm_crtc_init_with_planes() invoking, we can kill
things like struct imx_drm_crtc, imx_drm_crtc_helper_funcs and related
functions completely.

Functions ipu_enable_vblank() and ipu_disable_vblank() are moved around
without changes, only for saving the forward declarations.
Signed-off-by: NShawn Guo <shawn.guo@linaro.org>
Cc: Philipp Zabel <p.zabel@pengutronix.de>
Acked-by: NPhilipp Zabel <p.zabel@pengutronix.de>
Link: http://patchwork.freedesktop.org/patch/msgid/1486458995-31018-13-git-send-email-shawnguo@kernel.org

Core code already makes drm_driver.get_vblank_counter hook optional by
letting drm_vblank_no_hw_counter be the default implementation for the
function hook.  So the drm_vblank_no_hw_counter assignment in the driver
code becomes redundant and can be removed now.
Signed-off-by: NShawn Guo <shawn.guo@linaro.org>
Cc: Alexey Brodkin <abrodkin@synopsys.com>
Cc: Liviu Dudau <liviu.dudau@arm.com>
Cc: Mali DP Maintainers <malidp@foss.arm.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Boris Brezillon <boris.brezillon@free-electrons.com>
Cc: Inki Dae <inki.dae@samsung.com>
Cc: Stefan Agner <stefan@agner.ch>
Cc: Xinliang Liu <z.liuxinliang@hisilicon.com>
Cc: Daniel Vetter <daniel.vetter@intel.com>
Cc: Philipp Zabel <p.zabel@pengutronix.de>
Cc: CK Hu <ck.hu@mediatek.com>
Cc: Neil Armstrong <narmstrong@baylibre.com>
Cc: Rob Clark <robdclark@gmail.com>
Cc: Marek Vasut <marex@denx.de>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Mark Yao <mark.yao@rock-chips.com>
Cc: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Cc: Maxime Ripard <maxime.ripard@free-electrons.com>
Cc: Jyri Sarha <jsarha@ti.com>
Cc: Eric Anholt <eric@anholt.net>
Acked-by: NMaxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: NBoris Brezillon <boris.brezillon@free-electrons.com>
Acked-by: NNeil Armstrong <narmstrong@baylibre.com>
Acked-by: NRussell King <rmk+kernel@armlinux.org.uk>
Reviewed-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: NAlexey Brodkin <abrodkin@synopsys.com>
Acked-by: NLiviu Dudau <liviu.dudau@arm.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1486458995-31018-3-git-send-email-shawnguo@kernel.org

Instead of receiving the num_crts as a parameter, we can read it
directly from the mode_config structure.  I audited the drivers that
invoke this helper and I believe all of them initialize the mode_config
struct accordingly, prior to calling the fb_helper.

I used the following coccinelle hack to make this transformation, except
for the function headers and comment updates.  The first and second
rules are split because I couldn't find a way to remove the unused
temporary variables at the same time I removed the parameter.

// <smpl>
@r@
expression A,B,D,E;
identifier C;
@@
(
- drm_fb_helper_init(A,B,C,D)
+ drm_fb_helper_init(A,B,D)
|
- drm_fbdev_cma_init_with_funcs(A,B,C,D,E)
+ drm_fbdev_cma_init_with_funcs(A,B,D,E)
|
- drm_fbdev_cma_init(A,B,C,D)
+ drm_fbdev_cma_init(A,B,D)
)

@@
expression A,B,C,D,E;
@@
(
- drm_fb_helper_init(A,B,C,D)
+ drm_fb_helper_init(A,B,D)
|
- drm_fbdev_cma_init_with_funcs(A,B,C,D,E)
+ drm_fbdev_cma_init_with_funcs(A,B,D,E)
|
- drm_fbdev_cma_init(A,B,C,D)
+ drm_fbdev_cma_init(A,B,D)
)

@@
identifier r.C;
type T;
expression V;
@@
- T C;
<...
when != C
- C = V;
...>
// </smpl>

Changes since v1:
 - Rebased on top of the tip of drm-misc-next.
 - Remove mention to sti since a proper fix got merged.
Suggested-by: NDaniel Vetter <daniel.vetter@intel.com>
Signed-off-by: NGabriel Krisman Bertazi <krisman@collabora.co.uk>
Reviewed-by: NEric Anholt <eric@anholt.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20170202162640.27261-1-krisman@collabora.co.uk

Remove the common code from the driver and use the
drm_fb_cma_prepare_fb() helper instead.
Moveover, call the helper from prepare_fb() plane hook .
Signed-off-by: NMarek Vasut <marex@denx.de>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Lucas Stach <l.stach@pengutronix.de>
Reviewed-by: NLucas Stach <l.stach@pengutronix.de>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20161114100732.3446-2-marex@denx.de
Link: http://patchwork.freedesktop.org/patch/msgid/1476451342-146510-1-git-send-email-dvyukov@google.com

drm_atomic_set_fence_for_plane() is smart and won't overwrite
plane_state->fence if the user already set an explicit fence there.

Cc: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: NPhilipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1478513013-3221-2-git-send-email-gustavo@padovan.org

We are checking for NULL here, when we should be checking for error
pointers.

Fixes: 54db5dec ("drm/imx: drop deprecated load/unload drm_driver ops")
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: NLucas Stach <l.stach@pengutronix.de>
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>

The imx_drm_bind function causes a warning in linux-next when
CONFIG_DRM_FBDEV_EMULATION is not set:

drivers/gpu/drm/imx/imx-drm-core.c: In function 'imx_drm_bind':
drivers/gpu/drm/imx/imx-drm-core.c:441:1: error: label 'err_unbind' defined but not used [-Werror=unused-label]

I don't understand why the warning only showed up now, as the
code has not been modified recently, but there is an obvious
fix in adding another #if for the symbol.
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Fixes: c1ff5a7a ("drm/imx: Remove local fbdev emulation Kconfig option")
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>

We don't support configuring active plane on-the-fly for imx-drm.
The relevant CRTC should be disabled before the plane configuration.
Of course, the plane itself should be disabled as well.
This patch adds active plane reconfiguration support by forcing CRTC
mode change and disabling-enabling plane in plane's ->atomic_update
callback.
Suggested-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Cc: Philipp Zabel <p.zabel@pengutronix.de>
Cc: David Airlie <airlied@linux.ie>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Peter Senna Tschudin <peter.senna@gmail.com>
Signed-off-by: NLiu Ying <gnuiyl@gmail.com>
Tested-by: NPeter Senna Tschudin <peter.senna@gmail.com>
Tested-by: NLucas Stach <l.stach@pengutronix.de>
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>

This allows the atomic helper to wait on them, instead of open-coding
the same in the imx-drm driver.
Signed-off-by: NLucas Stach <l.stach@pengutronix.de>
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>

Instead let drm_mode_config_cleanup() do the work when taking down
the master device. This requires all cleanup functions to be
properly hooked up to the mode object .destroy callback.
Signed-off-by: NLucas Stach <l.stach@pengutronix.de>
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>

Drop the load/unload driver ops, as they are deprecated because of their
inherent races, with devices being visible to userspace before they are
fully initialized.

Move this code into the driver bind/unbind routines bracketed by the
proper drm_dev_alloc/register and drm_dev_unregister/unref calls.
Signed-off-by: NLucas Stach <l.stach@pengutronix.de>
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>

We don't support configuring active plane on-the-fly for imx-drm.
The relevant CRTC should be disabled before the plane configuration.
Of course, the plane itself should be disabled as well.

This patch adds active plane reconfiguration support by forcing CRTC
mode change in plane's ->atomic_check callback so that the CRTC
will be disabled before the plane configuration.
Suggested-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Cc: Philipp Zabel <p.zabel@pengutronix.de>
Cc: David Airlie <airlied@linux.ie>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Peter Senna Tschudin <peter.senna@gmail.com>
Cc: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: NLiu Ying <gnuiyl@gmail.com>
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>

The IPUv3 display controller behind imx-drm needs all planes of
a CRTC be disabled when the CRTC is disabled.
The DRM_PLANE_COMMIT_NO_DISABLE_AFTER_MODESET flag reflects this
hardware requirement.  Let's use the flag for imx-drm.
Suggested-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Cc: Philipp Zabel <p.zabel@pengutronix.de>
Cc: David Airlie <airlied@linux.ie>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Peter Senna Tschudin <peter.senna@gmail.com>
Cc: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: NLiu Ying <gnuiyl@gmail.com>
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>

Drivers may set the NO_DISABLE_AFTER_MODESET flag in the 'flags' parameter
of the helper drm_atomic_helper_commit_planes() if the relevant display
controllers(e.g., IPUv3 for imx-drm) require to disable a CRTC's planes
when the CRTC is disabled. The helper would skip the ->atomic_disable
call for a plane if the CRTC of the old plane state needs a modesetting
operation. Of course, the drivers need to disable the planes in their CRTC
disable callbacks since no one else would do that.
Suggested-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Cc: Philipp Zabel <p.zabel@pengutronix.de>
Cc: David Airlie <airlied@linux.ie>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Peter Senna Tschudin <peter.senna@gmail.com>
Cc: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: NLiu Ying <gnuiyl@gmail.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1472461923-14364-1-git-send-email-gnuiyl@gmail.com

Everyone who uses the fbdev emulation helpers doesn't need to include
fb.h directly. Remove it.
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1470847958-28465-3-git-send-email-daniel.vetter@ffwll.ch

imx_drm_handle_vblank() is just a simple wrapper of drm_crtc_handle_vblank()
without doing any thing fancy - drm_crtc_handle_vblank() can be called
directly.  So, let's remove the wrapper.
Signed-off-by: NLiu Ying <gnuiyl@gmail.com>
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>

There is no one calling imx_drm_crtc_id() and it is just a simple
wrapper of drm_crtc_index() without doing any thing fancy - the
drivers may call drm_crtc_index() directly.  So, let's remove the
wrapper.
Signed-off-by: NLiu Ying <gnuiyl@gmail.com>
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>

There is no one calling imx_drm_crtc_vblank_get/_put() and
they are just two simple wrappers of drm_crtc_vblank_get/_put()
without doing any thing fancy - the drivers may call
drm_crtc_vblank_get/_put() directly.  So, let's remove the two
wrappers.
Signed-off-by: NLiu Ying <gnuiyl@gmail.com>
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>

With all the beforehand phases and steps done, we can adverstise DRIVER_ATOMIC.
Signed-off-by: NLiu Ying <gnuiyl@gmail.com>
Acked-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>

Replacing drm_crtc_helper_set_config() by drm_atomic_helper_set_config()
and converting the suspend/resume operations to atomic make us be able
to use atomic configurations.  All of these allow us to remove the
crtc_funcs->mode_set callback as it is no longer used.  Also, change
the plane_funcs->update/disable_plane callbacks from the transitional
version to the atomic version.  Furthermore, switching to the pure atomic
version of set_config callback means that we may implement CRTC/plane
atomic checks by using the new CRTC/plane states instead of the legacy
ones and we may remove the private ipu_crtc->enabled state which was left
there for the transitional atomic helpers in phase 1.  Page flip is also
switched to the atomic version.  Last, the legacy function
drm_helper_disable_unused_functions() is removed from ->load in order
not to confuse the atomic driver.
Signed-off-by: NLiu Ying <gnuiyl@gmail.com>
Acked-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>

The main task of imx encoders' ->prepare callbacks is to set bus_format,
bus_flags, di_vsync_pin and di_hsync_pin.  We may create a structure named
imx_encoder to cache them.  The atomic encoder callback ->disable may
replace ->prepare later, so let's remove ->prepare.
Signed-off-by: NLiu Ying <gnuiyl@gmail.com>
Acked-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>

Wire up CRTCs', planes' and connectors' ->reset, ->duplicate and ->destroy state
hooks to use the default implementations from the atomic helper library.
The helpers track each DRM object state.
Signed-off-by: NLiu Ying <gnuiyl@gmail.com>
Acked-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>

We already have a fallback in place to fill out the unique from
dev->unique, which is set to something reasonable in drm_dev_alloc.

Which means we only need to have a special set_busid for pci devices,
to be able to care the backwards compat code for drm 1.1 around, which
libdrm still needs.

While developing and testing this patch things blew up in really
interesting ways, and the code is rather confusing in naming things
between the kernel code, ioctl #defines and libdrm. For the next brave
dragon slayer, document all this madness properly in the userspace
interface section of gpu.tmpl.

v2: Make drm_dev_set_unique static and update kerneldoc.

v3: Entire rewrite, plus document what's going on for posterity in the
gpu docbook uapi section.

v4: Drop accidental amdgpu hunk (Emil).

v5: Drop accidental omapdrm vblank counter change (Emil).

v6: Rebase on top of the sphinx conversion.

Cc: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Cc: Emil Velikov <emil.l.velikov@gmail.com>
Tested-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk> (virt_gpu)
Reviewed-by: NEmil Velikov <emil.l.velikov@gmail.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>