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>

list_for_each_entry_safe is for walking a list safe against removal
of entries. Here, no entries are removed, so use list_for_each_entry.
Signed-off-by: NSascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: NDave Airlie <airlied@redhat.com>

This function returns the number of planes used by a specific pixel
format.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NRob Clark <rob.clark@linaro.org>
Signed-off-by: NDave Airlie <airlied@redhat.com>

Call connector->funcs->dpms(DPMS_ON) rather than just setting
connector->dpms = DPMS_ON.  This ensures that if the connector
has something to do to enable the output (rather than just using
drm_helper_connector_dpms helper directly), that this happens
at bootup.  This solves an issue with connectors not getting
enabled from fbcon_init() when the driver is loaded.
Signed-off-by: NRob Clark <rob@ti.com>
Reviewed-by: NAdam Jackson <ajax@redhat.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

Otherwise each driver would need to keep the information inside
their own framebuffer object structure. Also add offsets[]. BOs
on the other hand are driver specific, so those can be kept in
driver specific structures.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

Disabling the CRTC by setting its framebuffer to NULL, as used by
drm_framebuffer_cleanup(), was failing to pass the current framebuffer
to the crtc_func->disable callback. This is because of the dance within
drm_crtc_helper_set_config to pass the new_fb (NULL in this case) to the
drm_crtc_helper_set_mode with the currently attached fb as a parameter.
drm_crtc_helper_set_mode treats this as a no-op and the encoder is still
enabled. And so the current fb is forgotten before the call to
drm_helper_disable_unused_functions.

This patch treats disabling the CRTC as a simple special case rather
than adding further complexity into the configuration logic.

This fixes a pin-leak of the fb bo on Xserver close.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDave Airlie <airlied@redhat.com>

This is used by nearly everyone including vmwgfx which doesn't generally
use the fb helper.
Signed-off-by: NDave Airlie <airlied@redhat.com>

To properly support the various plane formats supported by different
hardware, the kernel must know the pixel format of a framebuffer object.
So add a new ioctl taking a format argument corresponding to a fourcc
name from the new drm_fourcc.h header file.  Implement the fb creation
hooks in terms of the new mode_fb_cmd2 using helpers where the old
bpp/depth values are needed.

v2: create DRM specific fourcc header file for sharing with libdrm etc
v3: fix rebase failure and use DRM fourcc codes in intel_display.c and
    update commit message
v4: make fb_cmd2 handle field into an array for multi-object formats
    pull in Ville's fix for the memcpy in drm_plane_init
    apply Ville's cleanup to zero out fb_cmd2 arg in drm_mode_addfb
v5: add 'flags' field for interlaced support (from Ville)
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Acked-by: NAlan Cox <alan@lxorguk.ukuu.org.uk>
Reviewed-by: NRob Clark <rob.clark@linaro.org>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NDave Airlie <airlied@redhat.com>

We restore the CRTC, encoder, and connector configurations, but if the
mode set failed, the attached display may have been turned off, so we
need to try set_config again to restore things to the way they were.
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Reviewed-by: NAlex Deucher <alexdeucher@gmail.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

Signed-off-by: NPaul Gortmaker <paul.gortmaker@windriver.com>

They need this to get all the EXPORT_SYMBOL variants and THIS_MODULE
Signed-off-by: NPaul Gortmaker <paul.gortmaker@windriver.com>

Signed-off-by: NAdam Jackson <ajax@redhat.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

To properly drive a framebuffer with a new depth or bpp, dither settings
and link bandwidth calculations may change, so make sure we go through a
full mode set in that case.
Reported-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NKeith Packard <keithp@keithp.com>

In drm_crtc_helper_set_config, instead of always forcing all outputs
to DRM_MODE_DPMS_ON, only set them if the CRTC is actually getting a
mode set, as any mode set will turn all outputs on.

This fixes https://lkml.org/lkml/2011/1/24/457Signed-off-by: NKeith Packard <keithp@keithp.com>
Cc: stable@kernel.org (2.6.37)
Reported-and-tested-by: NCarlos R. Mafra <crmafra2@gmail.com>
Tested-by: NTakashi Iwai <tiwai@suse.de>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>

By setting the FB of a CRTC to NULL, we are turning off the CRTC (and so
disable the unused encoders and connectors). As such we can simplify the
later tests by making sure the set->mode is NULL. Setting the
num_connectors to zero means that we do not need to loop over the unused
connectors.

All current usage appears correct, this only builds additional defense
into the routine.

References: https://bugzilla.kernel.org/show_bug.cgi?id=27722Tested-by: NTakashi Iwai <tiwai@suse.de>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>

In drm_crtc_helper_set_config, we call drm_crtc_helper_set_mode which
may return early and do no operation if the crtc is to be disabled. In
this case we merrily swap to the new fb, discarding the old_fb believing
that it has been cleaned up. However, due to the early return, the
old_fb was not presented to the backend for correct reaping, and nor was
the new one - which is about to be reaped via the
drm_helper_disable_unused_functions(), leading to incorrect refcounting
of the pinned objects.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=27722
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=29857
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=29230Tested-by: NTakashi Iwai <tiwai@suse.de>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>

... or else we may end up disabling the wrong framebuffer, leading to an
OOPS, e.g:

[ 6033.229012] kernel BUG at drivers/gpu/drm/i915/i915_gem.c:3271!
[ 6033.229012] invalid opcode: 0000 [#1] SMP
[ 6033.229012] last sysfs file:
/sys/devices/virtual/backlight/acpi_video0/uevent
[ 6033.229012] Modules linked in: sunrpc cpufreq_ondemand acpi_cpufreq
mperf snd_hda_codec_analog snd_hda_intel snd_hda_codec snd_hwdep snd_seq
snd_seq_device snd_pcm snd_timer thinkpad_acpi ppdev snd r852 sm_common
iTCO_wdt uvcvideo i2c_i801 iTCO_vendor_support microcode wmi nand
videodev nand_ids nand_ecc snd_page_alloc parport_pc parport mtd
soundcore joydev v4l1_compat pcspkr uinput ipv6 sdhci_pci sdhci mmc_core
yenta_socket i915 drm_kms_helper drm i2c_algo_bit i2c_core video output
[last unloaded: scsi_wait_scan]
[ 6033.229012]
[ 6033.229012] Pid: 4834, comm: Xorg Not tainted 2.6.37-rc8+ #25 7661BL5/7661BL5
[ 6033.229012] EIP: 0060:[<f86fda5e>] EFLAGS: 00013246 CPU: 0
[ 6033.229012] EIP is at i915_gem_object_unpin+0x23/0x76 [i915]
[ 6033.229012] EAX: f68a4000 EBX: f6831f00 ECX: 000600fa EDX: f68a8000
[ 6033.229012] ESI: f68a4014 EDI: f68a42b8 EBP: f2169c44 ESP: f2169c3c
[ 6033.229012]  DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068
[ 6033.229012] Process Xorg (pid: 4834, ti=f2168000 task=f21c8000 task.ti=f2168000)
[ 6033.229012] Stack:
[ 6033.229012]  f3a84800 f68a4014 f2169c54 f87045d8 f3a84800 f872d9a8 f2169c68 f7fd8091
[ 6033.229012]  f3b952a4 00000000 f68a414c f2169cf0 f7fd9377 00000000 00000000 f7fd98b0
[ 6033.229012]  f7fd9f4e 0000000f f7f328a0 00000000 00000000 00000000 f2169ca4 f68a414c
[ 6033.229012] Call Trace:
[ 6033.229012]  [<f87045d8>] ? intel_crtc_disable+0x36/0x41 [i915]
[ 6033.229012]  [<f7fd8091>] ?  drm_helper_disable_unused_functions+0xcd/0xf9 [drm_kms_helper]
[ 6033.229012]  [<f7fd9377>] ? drm_crtc_helper_set_config+0x62a/0x7f7 [drm_kms_helper]
[ 6033.229012]  [<c04daa10>] ? __slab_free+0x1b/0xa4
[ 6033.229012]  [<f7fd7e62>] ? drm_fb_helper_initial_config+0x466/0x497 [drm_kms_helper]
[ 6033.229012]  [<f7fd7ea3>] ? drm_fb_helper_restore+0x10/0x2a [drm_kms_helper]
[ 6033.229012]  [<f86f2577>] ? i915_driver_lastclose+0x2a/0x57 [i915]
[ 6033.229012]  [<f7f1989f>] ? drm_lastclose+0x45/0x23e [drm]
[ 6033.229012]  [<f7f1a0b4>] ? drm_release+0x462/0x4d7 [drm]
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: stable@kernel.org
Signed-off-by: NDave Airlie <airlied@redhat.com>

Always useful to know just which connector was polled and had its
status updated.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDave Airlie <airlied@redhat.com>

This reverts commit 541cc966.

Wei Yonjun reported this caused a regression against Intel VGA hotplug
on his G33 hw.
Signed-off-by: NDave Airlie <airlied@redhat.com>

Prevents code that assumes that the encoder is active when asked to be
disabled from dying a horrible death.
Reported-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDave Airlie <airlied@redhat.com>

In order to correctly report monitor connected status changes, the
previous monitor status must be recorded in the connector->status
value instead of being discarded.
Signed-off-by: NKeith Packard <keithp@keithp.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

When setting a new crtc configuration, force the DPMS state of all
connectors to ON. Otherwise, they'll be left at OFF and a future mode set
that disables the specified connector will not turn the connector off.
Signed-off-by: NKeith Packard <keithp@keithp.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

The DRI2 swap & sync implementation needs precise
vblank counts and precise timestamps corresponding
to those vblank counts. For conformance to the OpenML
OML_sync_control extension specification the DRM
timestamp associated with a vblank count should
correspond to the start of video scanout of the first
scanline of the video frame following the vblank
interval for that vblank count.

Therefore we need to carry around precise timestamps
for vblanks. Currently the DRM and KMS drivers generate
timestamps ad-hoc via do_gettimeofday() in some
places. The resulting timestamps are sometimes not
very precise due to interrupt handling delays, they
don't conform to OML_sync_control and some are wrong,
as they aren't taken synchronized to the vblank.

This patch implements support inside the drm core
for precise and robust timestamping. It consists
of the following interrelated pieces.

1. Vblank timestamp caching:

A per-crtc ringbuffer stores the most recent vblank
timestamps corresponding to vblank counts.

The ringbuffer can be read out lock-free via the
accessor function:

struct timeval timestamp;
vblankcount = drm_vblank_count_and_time(dev, crtcid, &timestamp).

The function returns the current vblank count and
the corresponding timestamp for start of video
scanout following the vblank interval. It can be
used anywhere between enclosing drm_vblank_get(dev, crtcid)
and drm_vblank_put(dev,crtcid) statements. It is used
inside the drmWaitVblank ioctl and in the vblank event
queueing and handling. It should be used by kms drivers for
timestamping of bufferswap completion.

The timestamp ringbuffer is reinitialized each time
vblank irq's get reenabled in drm_vblank_get()/
drm_update_vblank_count(). It is invalidated when
vblank irq's get disabled.

The ringbuffer is updated inside drm_handle_vblank()
at each vblank irq.

2. Calculation of precise vblank timestamps:

drm_get_last_vbltimestamp() is used to compute the
timestamp for the end of the most recent vblank (if
inside active scanout), or the expected end of the
current vblank interval (if called inside a vblank
interval). The function calls into a new optional kms
driver entry point dev->driver->get_vblank_timestamp()
which is supposed to provide the precise timestamp.
If a kms driver doesn't implement the entry point or
if the call fails, a simple do_gettimeofday() timestamp
is returned as crude approximation of the true vblank time.

A new drm module parameter drm.timestamp_precision_usec
allows to disable high precision timestamps (if set to
zero) or to specify the maximum acceptable error in
the timestamps in microseconds.

Kms drivers could implement their get_vblank_timestamp()
function in a gpu specific way, as long as returned
timestamps conform to OML_sync_control, e.g., by use
of gpu specific hardware timestamps.

Optionally, kms drivers can simply wrap and use the new
utility function drm_calc_vbltimestamp_from_scanoutpos().
This function calls a new optional kms driver function
dev->driver->get_scanout_position() which returns the
current horizontal and vertical video scanout position
of the crtc. The scanout position together with the
drm_display_timing of the current video mode is used
to calculate elapsed time relative to start of active scanout
for the current video frame. This elapsed time is subtracted
from the current do_gettimeofday() time to get the timestamp
corresponding to start of video scanout. Currently
non-interlaced, non-doublescan video modes, with or
without panel scaling are handled correctly. Interlaced/
doublescan modes are tbd in a future patch.

3. Filtering of redundant vblank irq's and removal of
some race-conditions in the vblank irq enable/disable path:

Some gpu's (e.g., Radeon R500/R600) send spurious vblank
irq's outside the vblank if vblank irq's get reenabled.
These get detected by use of the vblank timestamps and
filtered out to avoid miscounting of vblanks.

Some race-conditions between the vblank irq enable/disable
functions, the vblank irq handler and the gpu itself (updating
its hardware vblank counter in the "wrong" moment) are
fixed inside vblank_disable_and_save() and
drm_update_vblank_count() by use of the vblank timestamps and
a new spinlock dev->vblank_time_lock.

The time until vblank irq disable is now configurable via
a new drm module parameter drm.vblankoffdelay to allow
experimentation with timeouts that are much shorter than
the current 5 seconds and should allow longer vblank off
periods for better power savings.

Followup patches will use these new functions to
implement precise timestamping for the intel and radeon
kms drivers.
Signed-off-by: NMario Kleiner <mario.kleiner@tuebingen.mpg.de>
Signed-off-by: NDave Airlie <airlied@redhat.com>

Coalesce long formats.
Align arguments.
Add missing newlines.
Signed-off-by: NJoe Perches <joe@perches.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

v2: Julien Cristau pointed out that @nondestructive results in
double-negatives and confusion when trying to interpret the parameter,
so use @force instead. Much easier to type as well. ;-)

And fix the miscompilation of vmgfx reported by Sedat Dilek.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: stable@kernel.org
Signed-off-by: NDave Airlie <airlied@redhat.com>

Destructive load-detection is very expensive and due to failings
elsewhere can trigger system wide stalls of up to 600ms. A simple
first step to correcting this is not to invoke such an expensive
and destructive load-detection operation automatically.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=29536
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=16265Reported-by: NBruno Prémont <bonbons@linux-vserver.org>
Tested-by: NSitsofe Wheeler <sitsofe@yahoo.com>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: stable@kernel.org
Signed-off-by: NDave Airlie <airlied@redhat.com>

Otherwise when disabling the output we switch to the new fb (which is
likely NULL) and skip the call to mode_set -- leaking driver private
state on the old_fb.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=29857Reported-by: NSitsofe Wheeler <sitsofe@yahoo.com>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Dave Airlie <airlied@redhat.com>
Cc: stable@kernel.org
Signed-off-by: NDave Airlie <airlied@redhat.com>

I broke out my trusty i845 and found a new boot failure, which upon
inspection turned out to be a recursion within:

drm_helper_probe_single_connector_modes() -> drm_helper_hpd_irq_event()
-> intel_crt_detect() -> drm_helper_probe_single_connector_modes()

Calling drm_kms_helper_poll_enable() instead performs the desired
re-initialisation of the polling should the user have toggled the
parameter, without the recursive side-effect.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Dave Airlie <airlied@redhat.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

Only fallback to a set of default modes on a connector iff that
connector is known to be connected. The issue occurs that with limited
hardware which cannot probe a connector and so reports the
connector status as unknown will then attempt to retrieve the modes for
it during drm_helper_probe_single_connector_modes(). Should that fail,
the helper then generates a default set which fools the fb_helper and
causes havoc with the console and beyond.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDave Airlie <airlied@redhat.com>

Polling for a VGA device on an old system can be quite expensive,
causing latencies on the order of 600ms. As we hold the mode mutex for
this time and also need the same mutex to move the cursor, we trigger a
user-visible stall.

The real solution would involve improving the granulatity of the
locking and so perhaps performing some of the probing not under the lock
or some other updates can be done under different locks. Also reducing the
cost of probing for a non-existent monitor would be worthwhile. However,
exposing a parameter to disable polling is a simple workaround in the
meantime.

In order to accommodate users turning polling on and off at runtime, the
polling is potentially re-enabled on every probe. This is coupled to
the user calling xrandr, which seems to be a vaild time to reset the
polling timeout since the information on the connection has just been
updated. (The presumption being that all connections are probed in a
single xrandr pass, which is currently valid.)

References:

  Bug 29536 - 2.6.35 causes ~600ms latency every 10s
  https://bugs.freedesktop.org/show_bug.cgi?id=29536

  Bug 16265 - Why is kslowd accumulating so much CPU time?
  https://bugzilla.kernel.org/show_bug.cgi?id=16265Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reported-and-tested-by: NBruno Prémont <bonbons@linux-vserver.org>
Signed-off-by: NDave Airlie <airlied@redhat.com>

Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDave Airlie <airlied@redhat.com>

Commit 991ea75c (drm: use workqueue instead of slow-work), which made
drm to use wq instead of slow-work, didn't account for the return
value difference between delayed_slow_work_enqueue() and
queue_delayed_work().  The former returns 0 on success and -errno on
failures while the latter never fails and only uses the return value
to indicate whether the work was already pending or not.

This misconversion triggered spurious error messages.  Remove the now
unnecessary return value check and error message.

Markus: caught another incorrect conversion in drm_kms_helper_poll_enable()
Signed-off-by: NTejun Heo <tj@kernel.org>
Reported-by: NMarkus Trippelsdorf <markus@trippelsdorf.de>
Tested-by: NMarkus Trippelsdorf <markus@trippelsdorf.de>
Cc: David Airlie <airlied@linux.ie>
Cc: dri-devel@lists.freedesktop.org

Workqueue can now handle high concurrency.  Convert drm_crtc_helper to
use system_nrt_wq instead of slow-work.  The conversion is mostly
straight forward.  One difference is that drm_helper_hpd_irq_event()
no longer blocks and can be called from any context.
Signed-off-by: NTejun Heo <tj@kernel.org>
Acked-by: NDavid Airlie <airlied@linux.ie>
Cc: dri-devel@lists.freedesktop.org

Unify debug printing so it easier to track what's happening
while debugging.
Signed-off-by: NJerome Glisse <jglisse@redhat.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

Original behaviour will be preserved for drivers that don't implement
disable() hooks for an encoder.
Signed-off-by: NBen Skeggs <bskeggs@redhat.com>
Reviewed-by: NAlex Deucher <alexdeucher@gmail.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

More explicit than dpms. Same as the encoder disable function.

Need this to explicity disconnect plls from crtcs for reuse when you
plls:crtcs ratio isn't 1:1.
Signed-off-by: NAlex Deucher <alexdeucher@gmail.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

Because we aren't in a suspend state the poll will still run when we have switcherooed a card off.
Signed-off-by: NDave Airlie <airlied@redhat.com>

After thinking it over a lot it made more sense for the core to deal with
the output polling especially so it can notify X.

v2: drop plans for fake connector - per Michel's comments - fix X patch sent to xorg-devel, add intel polled/hpd setting, add initial nouveau polled/hpd settings.

v3: add config lock take inside polling, add intel/nouveau poll init/fini calls

v4: config lock was a bit agressive, only needed around connector list reading.
otherwise it could re-enter.

glisse: discard drm_helper_hpd_irq_event

v3: Reviewed-by: Michel Dänzer <michel@daenzer.net>
Signed-off-by: NDave Airlie <airlied@redhat.com>