sed -e 's/\( \* .*\)struct &\([_a-z]*\)/\1\&struct \2/' -i

Originally I wasnt a friend of this style because I thought a
line-break between the "&struct" and "foo" part would break it. But a
quick test shows that " * &struct \n * foo\n" works pefectly well with
current kernel-doc. So time to mass-apply these changes!

Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NDavid Herrmann <dh.herrmann@gmail.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1483044517-5770-6-git-send-email-daniel.vetter@ffwll.ch

Apparently my arm .config had reverted to CMA=n at some point, so I
failed to notice that I typoed the code. Fix it up so that the
cma helper will compile again.
Reported-by: Nkbuild test robot <fengguang.wu@intel.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Fixes: ca984a99 ("drm/fb_cma_helper: Replace drm_format_info() with fb->format")
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161215142927.20761-1-ville.syrjala@linux.intel.comReviewed-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>

Replace uses of fb->pixel_format with fb->format->format.
Less duplicated information is a good thing.

Note that coccinelle failed to eliminate the
"/* fourcc format */" comment from drm_framebuffer.h, so I had
to do that part manually.

@@
struct drm_framebuffer *FB;
expression E;
@@
 drm_helper_mode_fill_fb_struct(...) {
	...
-	FB->pixel_format = E;
	...
 }

@@
struct drm_framebuffer *FB;
expression E;
@@
 i9xx_get_initial_plane_config(...) {
	...
-	FB->pixel_format = E;
	...
 }

@@
struct drm_framebuffer *FB;
expression E;
@@
 ironlake_get_initial_plane_config(...) {
	...
-	FB->pixel_format = E;
	...
 }

@@
struct drm_framebuffer *FB;
expression E;
@@
 skylake_get_initial_plane_config(...) {
	...
-	FB->pixel_format = E;
	...
 }

@@
struct drm_framebuffer *a;
struct drm_framebuffer b;
@@
(
- a->pixel_format
+ a->format->format
|
- b.pixel_format
+ b.format->format
)

@@
struct drm_plane_state *a;
struct drm_plane_state b;
@@
(
- a->fb->pixel_format
+ a->fb->format->format
|
- b.fb->pixel_format
+ b.fb->format->format
)

@@
struct drm_crtc *CRTC;
@@
(
- CRTC->primary->fb->pixel_format
+ CRTC->primary->fb->format->format
|
- CRTC->primary->state->fb->pixel_format
+ CRTC->primary->state->fb->format->format
)

@@
struct drm_mode_set *set;
@@
(
- set->fb->pixel_format
+ set->fb->format->format
|
- set->crtc->primary->fb->pixel_format
+ set->crtc->primary->fb->format->format
)

@@
@@
 struct drm_framebuffer {
	 ...
-	 uint32_t pixel_format;
	 ...
 };

v2: Fix commit message (Laurent)
    Rebase due to earlier removal of many fb->pixel_format uses,
    including the 'fb->format = drm_format_info(fb->format->format);'
    snafu
v3: Adjusted the semantic patch a bit and regenerated due to code
    changes

Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com> (v1)
Reviewed-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1481751175-18463-1-git-send-email-ville.syrjala@linux.intel.com

Replace uses of fb->depth with fb->format->depth. Less duplicate
information is a good thing.

@@
struct drm_framebuffer *fb;
expression E;
@@
 drm_helper_mode_fill_fb_struct(...) {
	...
-	fb->depth = E;
	...
 }

@@
struct nouveau_framebuffer *fb;
@@
- fb->base.depth
+ fb->base.format->depth

@@
struct drm_framebuffer fb;
@@
- fb.depth
+ fb.format->depth

@@
struct drm_framebuffer *fb;
@@
- fb->depth
+ fb->format->depth

@@
struct drm_framebuffer fb;
@@
- (fb.format->depth)
+ fb.format->depth

@@
struct drm_framebuffer *fb;
@@
- (fb->format->depth)
+ fb->format->depth

@@
@@
 struct drm_framebuffer {
	 ...
-	 unsigned int depth;
	 ...
 };

v2: Drop the vmw stuff (Daniel)
    Rerun spatch due to code changes
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1481751095-18249-1-git-send-email-ville.syrjala@linux.intel.com

Get the format information via the neat fb->format pointer rather than
doing a linear search over all the format info structures.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1479498793-31021-27-git-send-email-ville.syrjala@linux.intel.com

Pass the drm_device to drm_helper_mode_fill_fb_struct() so that we can
populate fb->dev early. Will make it easier to use the fb before we
register it.

@@
identifier fb, mode_cmd;
@@
 void drm_helper_mode_fill_fb_struct(
+				     struct drm_device *dev,
				     struct drm_framebuffer *fb,
				     const struct drm_mode_fb_cmd2 *mode_cmd
				     );

@@
identifier fb, mode_cmd;
@@
 void drm_helper_mode_fill_fb_struct(
+				     struct drm_device *dev,
				     struct drm_framebuffer *fb,
				     const struct drm_mode_fb_cmd2 *mode_cmd
				     )
{ ... }

@@
function func;
identifier dev;
expression E1, E2;
@@
func(struct drm_device *dev, ...)
{
 ...
 drm_helper_mode_fill_fb_struct(
+				dev,
				E1, E2);
 ...
}

@@
expression E1, E2;
@@
 drm_helper_mode_fill_fb_struct(
+				dev,
				E1, E2);

v2: Rerun spatch due to code changes
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1481748539-18283-1-git-send-email-ville.syrjala@linux.intel.com

Add new drm_fb_cma_prepare_fb() helper function extracted from the
imx-drm driver. This function checks if the plane has DMABUF attached
to it, extracts the exclusive fence from it and attaches it to the
plane state for the atomic helper to wait on it.
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/20161114100732.3446-1-marex@denx.de

Cc: David Airlie <airlied@linux.ie>
Signed-off-by: NStefan Christ <contact@stefanchrist.eu>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1479078208-25221-7-git-send-email-contact@stefanchrist.eu

If fbdev emulation is not in use (or not built-in), fb_helper.fbdev
is NULL. Don't call calling drm_fbdev_cma_defio_fini in this case.
Signed-off-by: NStefan Agner <stefan@agner.ch>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20161020003221.2941-2-stefan@agner.ch

Replace calls to the drm_format_*() helper functions with direct use of
the drm_format_info structure. This improves efficiency by removing
duplicate lookups.
Signed-off-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: NEric Engestrom <eric.engestrom@imgtec.com>
Signed-off-by: NArchit Taneja <architt@codeaurora.org>
Link: http://patchwork.freedesktop.org/patch/msgid/1476744081-24485-4-git-send-email-laurent.pinchart@ideasonboard.com

Implement a suspend/resume helper for CMA users which calls
drm_fb_helper_set_suspend.
Suggested-by: NThierry Reding <thierry.reding@gmail.com>
Acked-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NStefan Agner <stefan@agner.ch>

We may have a situation that the memory allocation for fbdefio fails
and then the allocation for fbops may succeed as some memory has been
freed somewhere. Lets free fbops also to face these rare situtation.
Since kfree can handle arguments as NULL, there should not be any
problem in calling both the kfree().
Signed-off-by: NSudip Mukherjee <sudip.mukherjee@codethink.co.uk>
Fixes: 199c7717 ("drm/fb-cma-helper: Add fb_deferred_io support")
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1465743836-6228-1-git-send-email-sudipm.mukherjee@gmail.com

In the absence of an fb_mmap callback, the fbdev code falls back to a
naive implementation which relies upon the DMA address being the same
as the physical address, and the buffer being physically contiguous
from there. Whilst this often holds for standard CMA allocations via
the platform's regular DMA ops, if the allocation is provided by an
IOMMU then such assumptions can fall apart spectacularly.

To resolve this, reroute the fb_mmap call to the appropriate DMA API
implementation, as per the other cma_helper calls.
Signed-off-by: NRobin Murphy <robin.murphy@arm.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/8fd95ac1440e0f01daad6d4380be3a4c8fa61055.1465301219.git.robin.murphy@arm.com

Just fallout from switching from asciidoc to sphinx/rst.

v2: Found more. Also s/\//#/ in the vgpu ascii-art - sphinx treats
those as comments and switch to variable-width, which wreaks the
layout.

v3: Undo some of the hacks, rebasing onto latest version of Jani's
series fixed it.
Acked-by: NLiviu Dudau <Liviu.Dudau@arm.com>
Acked-by: NJani Nikula <jani.nikula@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>

kernel-doc was unhappy, appease it.

v2: Resolve typo Liviu spotted through more consistency (aka
copy-pasting from drm_helper_mode_fill_fb_struct).

Cc: Noralf Trønnes <noralf@tronnes.org>
Cc: laurent.pinchart@ideasonboard.com
Acked-by: NLiviu Dudau <Liviu.Dudau@arm.com>
Acked-by: NJani Nikula <jani.nikula@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1464729075-22243-3-git-send-email-daniel.vetter@ffwll.ch

Since the introduction of (struct_mutex) lockless GEM bo freeing, there
are a pair of driver vfuncs for freeing the GEM bo, of which the driver
may choose to only implement driver->gem_object_free_unlocked (and so
avoid taking the struct_mutex along the free path). However, the CMA GEM
helpers were still calling driver->gem_free_object directly, now NULL,
and promptly dying on the fancy new lockless drivers. Oops.

Robert Foss bisected this to b82caafc (drm/vc4: Use lockless gem BO
free callback) on his vc4 device, but that just serves as an enabler for
9f0ba539 (drm/gem: support BO freeing without dev->struct_mutex).
Reported-by: NRobert Foss <robert.foss@collabora.com>
Fixes: 9f0ba539 (drm/gem: support BO freeing without dev->struct_mutex)
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Robert Foss <robert.foss@collabora.com>
Cc: Daniel Vetter <daniel.vetter@intel.com>
Cc: Eric Anholt <eric@anholt.net>
Cc: Alex Deucher <alexdeucher@gmail.com>
Cc: Lucas Stach <l.stach@pengutronix.de>
Cc: stable@vger.kernel.org
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Tested-by: NRobert Foss <robert.foss@collabora.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

Add drm_fb_cma_create_with_funcs() for drivers that need to set the
dirty() callback.
Signed-off-by: NNoralf Trønnes <noralf@tronnes.org>
Acked-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1463077523-23959-3-git-send-email-noralf@tronnes.org

drm_framebuffer_init() uses const for the drm_framebuffer_funcs
argument so use that on drm_fb_cma_alloc() and
drm_fbdev_cma_create_with_funcs() as well.

Cc: laurent.pinchart@ideasonboard.com
Signed-off-by: NNoralf Trønnes <noralf@tronnes.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1463077523-23959-2-git-send-email-noralf@tronnes.org

drm_gem_object_lookup() has never required the drm_device for its file
local translation of the user handle to the GEM object. Let's remove the
unused parameter and save some space.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: dri-devel@lists.freedesktop.org
Cc: Dave Airlie <airlied@redhat.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
[danvet: Fixup kerneldoc too.]
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Hook up fb_cma_helper to DocBook. Remove mention of
CONFIG_FB_DEFERRED_IO in the docs, which was forgotten in the latest
version of the deferred_io patch.
Use & when referencing drm_mode_config_funcs in docs.
Signed-off-by: NNoralf Trønnes <noralf@tronnes.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1462982962-10530-3-git-send-email-noralf@tronnes.org

This adds fbdev deferred io support if CONFIG_FB_DEFERRED_IO is enabled.
The driver has to provide a (struct drm_framebuffer_funcs *)->dirty()
callback to get notification of fbdev framebuffer changes.
If the dirty() hook is set, then fb_deferred_io is set up automatically
by the helper.

Two functions have been added so that the driver can provide a dirty()
function:
- drm_fbdev_cma_init_with_funcs()
  This makes it possible for the driver to provided a custom
  (struct drm_fb_helper_funcs *)->fb_probe() function.
- drm_fbdev_cma_create_with_funcs()
  This is used by the .fb_probe hook to set a driver provided
  (struct drm_framebuffer_funcs *)->dirty() function.

Cc: laurent.pinchart@ideasonboard.com
Signed-off-by: NNoralf Trønnes <noralf@tronnes.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1461856717-6476-6-git-send-email-noralf@tronnes.org

Duplicated const, only one is required.  Also reformat line to ensure
it is less than 80 columns wide.
Signed-off-by: NColin Ian King <colin.king@canonical.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1453287574-3645-1-git-send-email-colin.king@canonical.comSigned-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

The drm_fbdev_cma_init function always calls the
drm_helper_disable_unused_functions. Since it's part of the usual probe
process, all the drivers using that helper will end up having their encoder
and CRTC disable functions called at probe if their device has not been
reported as enabled.

This could be fixed by reading out from the registers the current state of
the device if it is enabled, but even that will not handle the case where
the device is actually disabled.

Moreover, the drivers using the atomic modesetting expect that their enable
and disable callback to be called when the device is already enabled or
disabled (respectively).

We can however fix this issue by moving the call to
drm_helper_disable_unused_functions out of drm_fbdev_cma_init and make the
drivers needing it (all the drivers calling drm_fbdev_cma_init and not
using the atomic modesetting) explicitly call it.
Signed-off-by: NMaxime Ripard <maxime.ripard@free-electrons.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1452785109-6172-14-git-send-email-maxime.ripard@free-electrons.comAcked-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

VC4 wraps the CMA objects in its own structures, so it needs to do its
own teardown (waiting for GPU to finish, updating bo_stats tracking).
The other CMA drivers are using drm_gem_cma_free_object as their
gem_free_object, so this should be a no-op for them.
Signed-off-by: NEric Anholt <eric@anholt.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Drivers shouldn't clobber the passed in addfb ioctl parameters.
i915 was doing just that. To prevent it from happening again,
pass the struct around as const, starting all the way from
internal_framebuffer_create().
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Use the newly created wrapper drm_fb_helper functions instead of calling
core fbdev functions directly. They also simplify the fb_info creation.

Cc: Lars-Peter Clausen <lars@metafoo.de>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NArchit Taneja <architt@codeaurora.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Remaining manual work in the drm core&helpers. Nothing special here,
no surprises.
Reviewed-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>

This function takes two locks, both of them the wrong ones. This
wasn't an oversight from my fb locking rework since both patches
landed in parallel. We really only need fb_lock when walking that
list, since everything we can reach from that is refcounted properly
already.

v2: Drop unused dev spotted by 0day.

Cc: Rob Clark <robdclark@gmail.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>

What is passed to drm_fb_helper_fill_var() should be fb_width/fb_height,
rather than the surface size.
Signed-off-by: NRob Clark <robdclark@gmail.com>
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Acked-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

To implement hotplug detection in a race-free manner, drivers must call
drm_kms_helper_poll_init() before hotplug events can be triggered. Such
events can be triggered right after any of the encoders or connectors
are initialized. At the same time, if the drm_fb_helper_hotplug_event()
helper is used by a driver, then the poll helper requires some parts of
the FB helper to be initialized to prevent a crash.

At the same time, drm_fb_helper_init() requires information that is not
necessarily available at such an early stage (number of CRTCs and
connectors), so it cannot be used yet.

Add a new helper, drm_fb_helper_prepare(), that initializes the bare
minimum needed to allow drm_kms_helper_poll_init() to execute and any
subsequent hotplug events to be processed properly.
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NThierry Reding <treding@nvidia.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

There's no need for this to be modifiable. Make it const so that it can
be put into the .rodata section.
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NThierry Reding <treding@nvidia.com>
Acked-by: NRussell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: NDave Airlie <airlied@redhat.com>

All drm_fb_helper_restore_fbdev_mode() call sites, save one, do the same
locking.  Simplify this into drm_fb_helper_restore_fbdev_mode_unlocked().
Signed-off-by: NRob Clark <robdclark@gmail.com>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NDave Airlie <airlied@redhat.com>

This function is only used in drm_fb_cma_helper.c.
Signed-off-by: NDamien Lespiau <damien.lespiau@intel.com>
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

Correct spelling typo in various part of drivers
Signed-off-by: NMasanari Iida <standby24x7@gmail.com>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

/me grabs a few brown paper bags

So it looks like I've broken compilation in

commit 6aed8ec3
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Sun Jan 20 17:32:21 2013 +0100

    drm: review locking for drm_fb_helper_restore_fbdev_mode

Fix it up again.

v2: Only deref fbdev_cma once we're sure it's non-NULL, noticed by
Thierry Reding.
Reported-by: NWu Fengguang <fengguang.wu@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: NThierry Reding <thierry.reding@avionic-design.de>
Signed-off-by: NDave Airlie <airlied@redhat.com>

Add helper to display fb's which can be used directly in drm_info_list:

static struct drm_info_list foo_debugfs_list[] = {
		...
		{ "fb",   drm_fb_cma_debugfs_show, 0 },
};

to display information about CMA fb objects, as well as a
drm_gem_cma_describe() which can be used if the driver bothers to keep
a list of CMA GEM objects.
Signed-off-by: NRob Clark <robdclark@gmail.com>

/me grabs a few brown paper bags

So it looks like I've broken compilation in

commit 6aed8ec3
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Sun Jan 20 17:32:21 2013 +0100

    drm: review locking for drm_fb_helper_restore_fbdev_mode

Fix it up again.
Reported-by: NWu Fengguang <fengguang.wu@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

The fb helper lost its support for reallocating an fb completely, so
no need to return special success values any more.
Reviewed-by: NRob Clark <robdclark@gmail.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This should be done in the drivers for two reasons:
- it gets in the way of fastboot efforts
- it links the fb helpers with the crtc helpers instead of going
  through the real interface vfuncs, forcing i915 to fake all the
  ->disable callbacks used by the crtc helper to avoid ugly Oopsen

v2: Resolve conflicts since drivers still call
drm_fb_helper_single_add_all_connectors.
Reviewed-by: NRob Clark <robdclark@gmail.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

... it's required. Fix up exynos and the cma helper, and add a
corresponding WARN_ON to drm_fb_helper_restore_fbdev_mode.

Note that tegra calls the fbdev cma helper restore function also from
it's driver-load callback. Which is a bit against current practice,
since usually the call is only from ->lastclose, and initial setup is
done by drm_fb_helper_initial_config.

Also add the relevant drm DocBook entry.

v2: Add promised WARN to restore_fbdev_mode.
Reviewed-by: NRob Clark <robdclark@gmail.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>