Bit-copying restoration of CRTC structure in failure-recovery
path of drm_crtc_helper_set_config function evokes a
subtle and rare, but very dangerous, corruption of
CRTC mutex structure.

Namely, if drm_crtc_helper_set_config takes the path under
'fail:' label *and* some other process has attempted to
grab the crtc mutex (and got blocked), restoring the CRTC
structure by bit-copying it will overwrite the CRTC mutex
state and the waiters list pointer within the mutex structure.
Consequently the blocked process will never be scheduled.

This patch fixes the issue by eliminating the bit-copy
restoration. The elimination is possible because previous
patches have cleaned up the resoration path so that only
the fields touched by the drm_crtc_helper_set_config function
are saved and restored if necessary.
Signed-off-by: NIlija Hadzic <ihadzic@research.bell-labs.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

There is no need to set crtc->enabled field in
drm_crtc_helper_set_config. This is already done (and
properly restored in case of failure) in
drm_crtc_helper_set_mode that is called by
drm_crtc_helper_set_config. Doing it at only one
place makes restoration in case of failure easier.
Signed-off-by: NIlija Hadzic <ihadzic@research.bell-labs.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

There is no need to save or restore hwmode field, because by
the time this function sets this field, it cannot fail any more.
However, we should save old enabled field because if
the function fails, we want to return with unchanged CRTC.
Signed-off-by: NIlija Hadzic <ihadzic@research.bell-labs.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

Signed-off-by: NIlija Hadzic <ihadzic@research.bell-labs.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

Old framebuffer is stored in save_set.fb and it is
the same value that is later stored in old_fb.
This makes old_fb redundant so we can replace
it with save_set.fb.
Signed-off-by: NIlija Hadzic <ihadzic@research.bell-labs.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

Signed-off-by: NIlija Hadzic <ihadzic@research.bell-labs.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

When userspace removes the active framebuffer using DRM_IOCTL_MODE_RMFB,
or explicitly disables the CRTC (by calling drmModeSetCrtc(..., NULL)
for example), a NULL framebuffer will be passed to the .set_config()
implementation of a CRTC. The drm_crtc_helper_set_config() helper will
decide to disable a CRTC when that happens.

To do so, it calls drm_crtc_helper_disable(), which in turn will iterate
over all encoders and decouple them from their connectors and finally
call drm_helper_disable_unused_functions() to clean up and call the
.disable() or .dpms() implementation for each encoder. However, at no
point during this sequence does it track the DPMS mode of a connector,
so it will usually remain on after this.

When a connector is enabled again, drm_helper_connector_dpms() will not
notice that the DPMS mode actually changed and won't do anything, which
causes the connector to stay disabled indefinitely.

To prevent this from happening, explicitly set the connector's DPMS mode
to off when the CRTC is disabled. That way it reflects the correct state
and can be enabled again.

This solves an issue observed when terminating an X server running on
the xf86-video-modesetting driver. Without this patch, the connector
would not be enabled properly and the screen would stay dark.
Acked-by: NDavid Airlie <airlied@linux.ie>
Signed-off-by: NThierry Reding <treding@nvidia.com>

The caller may want to know whether the configuration was changed, and
if an hotplug event was sent.
Signed-off-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

For drivers which might want to disable fbdev legacy support.

Select the new option in all drivers for now, so this shouldn't result
in any change. Drivers need some work anyway to make fbdev support
optional (if they have it implemented, that is), so the recommended
way to expose this is by adding per-driver options. At least as long
as most drivers don't support disabling the fbdev support.

v2: Update for new drm drivers msm and rcar-du. Note that Rob's msm
driver can already take advantage of this, which allows us to build
msm without any fbdev depencies in the kernel!

v3: Move the MODULE_* stuff from the fbdev helper file to
drm_crtc_helper.c.

Cc: David Herrmann <dh.herrmann@gmail.com>
Cc: Rob Clark <robdclark@gmail.com>
Reviewed-by: NRob Clark <robdclark@gmail.com>
Acked-by: NDave Airlie <airlied@linux.ie>
Reviewed-by: NChon Ming Lee <chon.ming.lee@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

drm_helper_probe_single_connector_modes() can be used to implement
->fill_modes(), not ->probe().
Signed-off-by: NDamien Lespiau <damien.lespiau@intel.com>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NDave Airlie <airlied@redhat.com>

Just like with interlaced or double scan modes, make stereo modes a
per-connector opt-in to give a chance to driver authors to make it work
before enabling it.
Suggested-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NDamien Lespiau <damien.lespiau@intel.com>
Acked-by: NDave Airlie <airlied@gmail.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This patch adds the notion of a drm_bridge. A bridge is a chained
device which hangs off an encoder. The drm driver using the bridge
should provide the association between encoder and bridge. Once a
bridge is associated with an encoder, it will participate in mode
set, and dpms (via the enable/disable hooks).
Signed-off-by: NSean Paul <seanpaul@chromium.org>
Acked-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: NRob Clark <robdclark@gmail.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

Atm the crtc helper implementation of set_config has really
inconsisten semantics: If just an fb update is good enough, dpms state
will be left as-is, but if we do a full modeset we force everything to
dpms on.

This change has already been applied to the i915 modeset code in

commit e3de42b6
Author: Imre Deak <imre.deak@intel.com>
Date:   Fri May 3 19:44:07 2013 +0200

    drm/i915: force full modeset if the connector is in DPMS OFF mode

which according to Greg KH seems to aim for a new record in most
Bugzilla: links in a commit message.

The history of this dpms forcing is pretty interesting. This patch
here is an almost-revert of

commit 811aaa55
Author: Keith Packard <keithp@keithp.com>
Date:   Thu Feb 3 16:57:28 2011 -0800

    drm: Only set DPMS ON when actually configuring a mode

which fixed the bug of trying to dpms on disabled outputs, but
introduced the new discrepancy between an fb update only and full
modesets. The actual introduction of this goes back to

commit bf9dc102
Author: Keith Packard <keithp@keithp.com>
Date:   Fri Nov 26 10:45:58 2010 -0800

    drm: Set connector DPMS status to ON in drm_crtc_helper_set_config

And if you'd dig around in the i915 driver code there's even more fun
around forcing dpms on and losing our heads and temper of the
resulting inconsistencies. Especially the DP re-training code had tons
of funny stuff in it.

v2: So v1 totally blew up on resume on my radeon system here. After
much head-scraching I've figured out that the radeon resume functions
resumes the console system _before_ it actually restores all the
modeset state. And resuming the console systems means that fbdev doeas
an immediate ->set_par call.

Now up to this patch that ->set_par did absolutely nothing: All the
old sw state from pre-suspend was still around (since the modeset
reset wasn't done yet), which means that the set_config calls done as
a result of the ->set_par where all treated as no-ops (despite that
the real hw state was obviously something completely different).

Since v1 of this patch just added a bunch of ->dpms calls if the crtc
was enabled, those set_config calls suddenly stopped being no-ops. But
because the hw state wasn't restored the ->dpms callbacks resulted in
decent amounts of hilarity and eventual full hangs.

Since I can't review all kms drivers for such tricky ordering
constraints v2 opts for a different approach and forces a full modeset
if the connector dpms state isnt' DPMS_ON. Since the ->dpms callbacks
implemented by the modeset helpers update the connector->dpms property
we have the same effect of ensuring that the pipe is ultimately turned
on, even if we just end up updating the fb. This is the same approac
we ended up using in the intel driver.

Note that besides i915.ko only all other drivers eventually call
drm_helper_connector_dpms with the exception of vmwgfx, which does not
support dmps at all.

v3: Dave Airlie merged the broken first version of this patch, so
squash in the revert of

commit 372835a8
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Sat Jun 15 00:13:13 2013 +0200

    drm/crtc-helper: explicit DPMS on after modeset

Also fix up the spelling fail a bit in the commit message while at it.

Cc: Dave Airlie <airlied@redhat.com>
Reviewed-by: NAlex Deucher <alexdeucher@gmail.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=67043Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NDave Airlie <airlied@redhat.com>

This reverts commit 160954b7.

This was rearming the workqueue with a 0 timeout, causing
a WARN_ON, and possible loop.

Daniel writes:
"I've looked a bit into this and I think we need to have a separate
work struct for recovering these lost hotplug events since the
continuous self-rearming case is a real risk (e.g. if a connector
flip-flops all the time). At least I don't see a sane way to block out
re-arming with the current code in a simple way. So reverting the
offender seems like the right thing and I'll go back to the drawing
board for 3.12."
Signed-off-by: NDave Airlie <airlied@redhat.com>

There's a race window (small for hpd, 10s large for polled outputs)
where userspace could sneak in with an unrelated connnector probe
ioctl call and eat the hotplug event (since neither the hpd nor the
poll code see a state change).

To avoid this, check whether the connector state changes in all other
->detect calls (in the current helper code that's only probe_single)
and if that's the case, fire off a hotplug event. Note that we can't
directly call the hotplug event handler, since that expects that no
locks are held (due to reentrancy with the fb code to update the kms
console).

Also, this requires that drivers using the probe_single helper
function set up the poll work. All current drivers do that already,
and with the reworked hpd handling there'll be no downside to
unconditionally setting up the poll work any more.
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NDave Airlie <airlied@redhat.com>

Atm the crtc helper implementation of set_config has really
inconsisten semantics: If just an fb update is good enough, dpms state
will be left as-is, but if we do a full modeset we force everything to
dpms on.

This change has already been applied to the i915 modeset code in

commit e3de42b6
Author: Imre Deak <imre.deak@intel.com>
Date:   Fri May 3 19:44:07 2013 +0200

    drm/i915: force full modeset if the connector is in DPMS OFF mode

which according to Greg KH seems to aim for a new record in most
Bugzilla: links in a commit message.

The history of this dpms forcing is pretty interesting. This patch
here is an almost-revert of

commit 811aaa55
Author: Keith Packard <keithp@keithp.com>
Date:   Thu Feb 3 16:57:28 2011 -0800

    drm: Only set DPMS ON when actually configuring a mode

which fixed the bug of trying to dpms on disabled outputs, but
introduced the new discrepancy between an fb update only and full
modesets. The actual introduction of this goes back to

commit bf9dc102
Author: Keith Packard <keithp@keithp.com>
Date:   Fri Nov 26 10:45:58 2010 -0800

    drm: Set connector DPMS status to ON in drm_crtc_helper_set_config

And if you'd dig around in the i915 driver code there's even more fun
around forcing dpms on and losing our heads and temper of the
resulting inconsistencies. Especially the DP re-training code had tons
of funny stuff in it.
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NDave Airlie <airlied@redhat.com>

... since we already check for fb->pixel_format, which encodes all
this. The other two fields are only for backwards compat of older
drivers (and we might want to look into eventually just killing them).
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NDave Airlie <airlied@redhat.com>

There's no point in trying to clean up after driver-bugs, so just blow
up. Furthermore it's an interface abuse to set no mode but have an fb
and aslo to try to set an fb without enough connectors. These two
spefici cases of interface abuse have been committed by the fb helper,
but that's been fixed meanwhile in

commit 7e53f3a4
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Mon Jan 21 10:52:17 2013 +0100

    drm/fb-helper: fixup set_config semantics

The i915 driver has been shipping since a while with these BUGs with
no reports, so should be save.

Note that this drops an ugly case where we clear crtc->fb behind the
upper levels back and so cause a refcounting mayhem, which Russell
Kins spotted while trying to hunt down a drm framebuffer leak.
Reported-by: NRussell King <linux@arm.linux.org.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NDave Airlie <airlied@redhat.com>

Keeping the modes sorted by vrefresh before the pixel clock makes the
mode list somehow more pleasing to the eye.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

Suggested-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDamien Lespiau <damien.lespiau@intel.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

Instead of just printing "status updated from 1 to 2", make those enum
numbers immediately readable.

v2: Also patch output_poll_execute() (Daniel Vetter)
v3: Use drm_get_connector_status_name (Ville Syrjälä)
Signed-off-by: NDamien Lespiau <damien.lespiau@intel.com>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org> (for v1)
Signed-off-by: NDave Airlie <airlied@redhat.com>

drm_helper_probe_single_connector_modes() is responsible for pruning the
previously detected modes on a disconnected connector. We don't really
need to log, again, the full list of modes that used to be valid when
connected.
Signed-off-by: NDamien Lespiau <damien.lespiau@intel.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

Test whether the pixel format changes in the mode set handler, and
perform a full mode set instead of a mode set base if it does.
Signed-off-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

The coup de grace of the entire journey. No more dropped frames every
10s on my testbox!

I've tried to audit all ->detect and ->get_modes callbacks, but things
became a bit fuzzy after trying to piece together the umpteenth
implemenation. Afaict most drivers just have bog-standard output
register frobbing with a notch of i2c edid reading, nothing which
could potentially race with the newly concurrent pageflip/set_cursor
code. The big exception is load-detection code which requires a
running pipe, but radeon/nouveau seem to to this without touching any
state which can be observed from page_flip (e.g. disabled crtcs
temporarily getting enabled and so a pageflip succeeding).

The only special case I could find is the i915 load detect code. That
uses the normal modeset interface to enable the load-detect crtc, and
so userspace could try to squeeze in a pageflip on the load-detect
pipe. So we need to grab the relevant crtc mutex in there, to avoid
the temporary crtc enabling to sneak out and be visible to userspace.

Note that the sysfs files already stopped grabbing the per-crtc locks,
since I didn't want to bother with doing a interruptible
modeset_lock_all. But since there's very little in-between breakage
(essentially just the ability for userspace to pageflip on load-detect
crtcs when it shouldn't on the i915 driver) I figured I don't need to
bother.
Reviewed-by: NRob Clark <rob@ti.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This is the first step towards introducing the new modeset locking
scheme. The plan is to put helper functions into place at all the
right places step-by-step, so that the final patch to switch on the
new locking scheme doesn't need to touch every single driver.

This helper here will serve as the shotgun solutions for all places
where a more fine-grained locking isn't (yet) implemented.

v2: Fixup kerneldoc for unlock_all.
Reviewed-by: NRob Clark <rob@ti.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

- Add the missing doc for drm_helper_move_panel_connectors_to_head.
- Fixup any outdated stuff in existing sections. I've only looked at
  those kerneldoc headers that actually resulted in a complaint from
  the kerneldoc parser tool.

v2:
- Actually include the docbook snippet in the right patch.
- Fix spelling fail.

v3: It's now called drm_crtc_helper_set_mode, spotted by Laurent
Pinchart.
Acked-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NDave Airlie <airlied@redhat.com>

... by properly checking connector->polled. This doesn't matter too
much because the polling work itself gets this slightly more right and
doesn't set repoll if there's nothing to do. But we can do better.

v2: Chris Wilson noticed that I broke polling, since repoll will never
ever be set true. Fix this up, and simplify the logic a bit while at
it.
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NDave Airlie <airlied@redhat.com>

Otherwise if the detect callback reports a different state than what
the user forced (rather likely), we continously annoy userspace about
a hotplug uevent.
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

Actually there's a reason this stuff is there, and it's called

commit e58f637b
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date:   Fri Aug 20 09:13:36 2010 +0100

    drm/kms: Add a module parameter to disable polling

The idea has been that users can enable/disable polling at runtime. So
the quick hack has been to just re-enable the output polling if xrandr
asks for the latest state of the connectors.

The problem with that hack is that when we force connectors to another
state than what would be detected, we nicely ping-pong:
- Userspace calls probe, gets the forced state, but polling starts
  again.
- Polling notices that the state is actually different, wakes up
  userspace.
- Repeat.

As that commit already explains, the right fix would be to make the
locking more fine-grained, so that hotplug detection on one output
does not interfere with cursor updates on another crtc.

But that is way too much work. So let's just safe this gross hack by
caching the last-seen state of drm_kms_helper_poll for that driver,
and only fire up the poll engine again if it changed from off to on.

v2: Fixup the edge detection of drm_kms_helper_poll.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=49907Tested-by: NTvrtko Ursulin <tvrtko.ursulin@onelan.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

All drivers already have a work item to run the hpd code, so we don't
need to launch a new one in the helper code. Dave Airlie mentioned
that the cancel+re-queue might paper over DP related hpd ping-pongs,
hence why this is split out.
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

Instead of reusing the polling code for hpd handling, split them up.
This has a few consequences:
- Don't touch HPD capable connectors in the poll loop.
- Only touch HPD capable connectors in drm_helper_hpd_irq_event.
- We could run the HPD handling directly (because all callers already
  use their own work item), but for easier bisect that happens in it's
  own patch.

The ultimate goal is that drivers grow some smarts about which
connectors have received a hotplug event and only call the detect code
of that connector. But that's a second step.

v2: s/hdp/hpd/, noticed by Adam Jackson. I can't type.

v3: Split out the work item removal as requested by Dave Airlie. This
results in a temporary mode_config.hpd_irq_work item to keep things
the same.

v4: In the hpd_irq_event handler don't bail out if other bits than HPD
are set. This is useful where e.g. hpd is unreliably, but mostly
works. Drivers can then set both HPD and POLL flags, and users get the
best of both worlds: Quick hotplug feedback if the hpd works, but
still reliable detection with the polling. The poll loop already works
the same, and doesn't bail if HPD is set.
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

Useful if drivers want to be slightly more clever about hotplug
handling.
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

x and y parameters are offsets, not width/height
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Signed-off-by: NDave Airlie <airlied@redhat.com>

Userspace seems to like this, see

commit cb0953d7
Author: Adam Jackson <ajax@redhat.com>
Date:   Fri Jul 16 14:46:29 2010 -0400

    drm/i915: Initialize LVDS and eDP outputs before anything else

    This makes them sort to the front in X, which makes them likely to be
    the primary outputs if you haven't specified a preference in your DE,
    which is likely to be what you want.
Signed-off-by: NAdam Jackson <ajax@redhat.com>
Signed-off-by: NEric Anholt <eric@anholt.net>

Sorting the connector list after the fact is much easier than trying
to be clever with the init sequence.
Acked-by: NDave Airlie <airlied@gmail.com>
Reviewed-by: NAdam Jackson <ajax@redhat.com>
Acked-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Convert #include "..." to #include <path/...> in drivers/gpu/.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Acked-by: NDave Airlie <airlied@redhat.com>
Acked-by: NArnd Bergmann <arnd@arndb.de>
Acked-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: NDave Jones <davej@redhat.com>

system_nrt[_freezable]_wq are now spurious.  Mark them deprecated and
convert all users to system[_freezable]_wq.

If you're cc'd and wondering what's going on: Now all workqueues are
non-reentrant, so there's no reason to use system_nrt[_freezable]_wq.
Please use system[_freezable]_wq instead.

This patch doesn't make any functional difference.
Signed-off-by: NTejun Heo <tj@kernel.org>
Acked-By: NLai Jiangshan <laijs@cn.fujitsu.com>

Cc: Jens Axboe <axboe@kernel.dk>
Cc: David Airlie <airlied@linux.ie>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: David Howells <dhowells@redhat.com>

Signed-off-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

There will be a need for this function in drm_crtc.c later. This
avoids making drm_crtc.c depend on drm_crtc_helper.c.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

Broken monitors and/or broken graphic boards may send erroneous or no
EDID data. This also applies to broken KVM devices that are unable to
correctly forward the EDID data of the connected monitor but invent
their own fantasy data.

This patch allows to specify an EDID data set to be used instead of
probing the monitor for it. It contains built-in data sets of frequently
used screen resolutions. In addition, a particular EDID data set may be
provided in the /lib/firmware directory and loaded via the firmware
interface. The name is passed to the kernel as module parameter of the
drm_kms_helper module either when loaded
  options drm_kms_helper edid_firmware=edid/1280x1024.bin
or as kernel commandline parameter
  drm_kms_helper.edid_firmware=edid/1280x1024.bin

It is also possible to restrict the usage of a specified EDID data set
to a particular connector. This is done by prepending the name of the
connector to the name of the EDID data set using the syntax
  edid_firmware=[<connector>:]<edid>
such as, for example,
  edid_firmware=DVI-I-1:edid/1920x1080.bin
in which case no other connector will be affected.

The built-in data sets are
Resolution    Name
--------------------------------
1024x768      edid/1024x768.bin
1280x1024     edid/1280x1024.bin
1680x1050     edid/1680x1050.bin
1920x1080     edid/1920x1080.bin

They are ignored, if a file with the same name is available in the
/lib/firmware directory.

The built-in EDID data sets are based on standard timings that may not
apply to a particular monitor and even crash it. Ideally, EDID data of
the connected monitor should be used. They may be obtained through the
drm/cardX/cardX-<connector>/edid entry in the /sys/devices PCI directory
of a correctly working graphics adapter.

It is even possible to specify the name of an EDID data set on-the-fly
via the /sys/module interface, e.g.
echo edid/myedid.bin >/sys/module/drm_kms_helper/parameters/edid_firmware
The new screen mode is considered when the related kernel function is
called for the first time after the change. Such calls are made when the
X server is started or when the display settings dialog is opened in an
already running X server.
Signed-off-by: NCarsten Emde <C.Emde@osadl.org>
Signed-off-by: NDave Airlie <airlied@redhat.com>

Check drm_mode_object_get() return value everywhere.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>