Looks like I've missed one of the potential NULL deref bugs in Jesse's
fbdev->fb embedded struct to pointer conversions. Fix it up.

This regression has been introduced in

commit 8bcd4553
Author: Jesse Barnes <jbarnes@virtuousgeek.org>
Date:   Fri Feb 7 12:10:38 2014 -0800

    drm/i915: alloc intel_fb in the intel_fbdev struct

Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

One side-effect of the introduction of ppgtt was that we needed to
rebind the object into the appropriate vm (and global gtt in some
peculiar cases). For simplicity this was done twice for every object on
every call to execbuffer. However, that adds a tremendous amount of CPU
overhead (rewriting all the PTE for all objects into WC memory) per
draw. The fix is to push all the decision about which vm to bind into
and when down into the low-level bind routines through hints rather than
performing the bind unconditionally in the execbuffer routine.

Note that this is a regression introduced in the full ppgtt feature
branch, before this we've only done re-bound objects when the relevant
has_(aliasing_ppgtt|global_gtt)_mapping flag was clear. But since
that's per-object and not per-vma that optimization broke.

v2: Split out prep work and unrelated changes.

v3: Bring back functional change around PIN_GLOBAL that I've
accidentally split out.

v4: Remove the temporary hack for the old binding logic to avoid
bisection issues.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=72906
Tested-by: jianx.zhou@intel.com
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> (v1)
Cc: Ben Widawsky <benjamin.widawsky@intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This is prep work for reworking the object_pin logic. Atm
it still does a (now redundant) lookup of the vma. The next
patch will fix this.

Split out from Chris vma-bind rework.

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Ben Widawsky <benjamin.widawsky@intel.com>
Reviewed-by: NJani Nikula <jani.nikula@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Split out from Chris vma-bind rework.

Jani wondered why this is save, and the reason is that i915_vma_unbind
does all these checks, too. So they're redundant.

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Ben Widawsky <benjamin.widawsky@intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

There's no need not to, really.

Split out from Chris vma-bind rework.

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Ben Widawsky <benjamin.widawsky@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Only the hardware really access them, so no need to have cpu
gtt access available.

Split out from Chris vma-bind rework.

Note that this is only possible due to the split-up of the mappable
pin flag into PIN_GLOBAL and PIN_MAPPABLE.

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Ben Widawsky <benjamin.widawsky@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Split out from Chris vma-bind rework.

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Ben Widawsky <benjamin.widawsky@intel.com>
Reviewed-by: NJani Nikula <jani.nikula@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

We access it through the cpu window. No functional difference expected
atm since we default to a bottom-up allocation scheme. But that might
eventually change so that we prefer the unmappable range for buffers
that don't need cpu gtt access.

Split out from Chris vma-bind rework.

Note that this is only possible due to the split-up of the mappable
pin flag into PIN_GLOBAL and PIN_MAPPABLE.

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Ben Widawsky <benjamin.widawsky@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Tighter code since legacy gem has only mappable anyway.

Split out from Chris vma-bind rework.

Note that this is only possible due to the split-up of the mappable
pin flag into PIN_GLOBAL and PIN_MAPPABLE.

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Ben Widawsky <benjamin.widawsky@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Split out from Chris vma-bind rework.

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Ben Widawsky <benjamin.widawsky@intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

With abitrary pin flags it makes sense to split out a "please bind
this into global gtt" from the "please allocate in the mappable
range".

Use this unconditionally in our global gtt pin helper since this is
what its callers want. Later patches will drop PIN_MAPPABLE where it's
not strictly needed.
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Anything more than just one bool parameter is just a pain to read,
symbolic constants are much better.

Split out from Chris' vma-binding rework patch.

v2: Undo the behaviour change in object_pin that Chris spotted.

v3: Split out misplaced hunk to handle set_cache_level errors,
spotted by Jani.

v4: Keep the current over-zealous binding logic in the execbuffer code
working with a quick hack while the overall binding code gets shuffled
around.

v5: Reorder the PIN_ flags for more natural patch splitup.

v6: Pull out the PIN_GLOBAL split-up again.

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Ben Widawsky <benjamin.widawsky@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This is the same what we do for DP connectors, so make things more
consistent.
Signed-off-by: NImre Deak <imre.deak@intel.com>
Reviewed-by: NAntti Koskipää <antti.koskipaa@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Signed-off-by: NImre Deak <imre.deak@intel.com>
Reviewed-by: NAntti Koskipää <antti.koskipaa@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Atm we set the parent of the dp i2c device to be the correspondig
connector device. During driver cleanup we first remove the connector
device through intel_modeset_cleanup()->drm_sysfs_connector_remove() and
only after that the i2c device through the encoder's destroy callback.
This order is not supported by the device core and we'll get a warning,
see the below bugzilla ticket. The proper order is to remove first any
child device and only then the parent device.

The first part of the fix changes the i2c device's parent to be the drm
device. Its logical owner is not the connector anyway, but the encoder.
Since the encoder doesn't have a device object, the next best choice is
the drm device. This is the same what we do in the case of the sdvo i2c
device and what the nouveau driver does.

The second part creates a symlink in the connector's sysfs directory
pointing to the i2c device. This is so, that we keep the current ABI,
which also makes sense in case someone wants to look up the i2c device
belonging to a specific connector.

Reference: http://lists.freedesktop.org/archives/intel-gfx/2014-January/038782.html
Reference: http://lists.freedesktop.org/archives/intel-gfx/2014-February/039427.html
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=70523Signed-off-by: NImre Deak <imre.deak@intel.com>
Reviewed-by: NAntti Koskipää <antti.koskipaa@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Since

commit d9255d57
Author: Paulo Zanoni <paulo.r.zanoni@intel.com>
Date:   Thu Sep 26 20:05:59 2013 -0300

it became clear that we need to separate the unload sequence into two
parts:

1. remove all interfaces through which new operations on some object
   (crtc, encoder, connector) can be started and make sure all pending
   operations are completed
2. do the actual tear down of the internal representation of the above
   objects

The above commit achieved this separation for connectors by splitting
out the sysfs removal part from the connector's destroy callback and
doing this removal before calling drm_mode_config_cleanup() which does
the actual tear-down of all the drm objects.

Since we'll have to customize the interface removal part for different
types of connectors in the upcoming patches, add a new unregister
callback and move the interface removal part to it.

No functional change.
Signed-off-by: NImre Deak <imre.deak@intel.com>
Reviewed-by: NAntti Koskipää <antti.koskipaa@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Reproducible by runtime suspending a Haswell machine with eDP + HDMI
outputs connected.

[  209.600086] [drm:i915_runtime_suspend], Suspending device
[  209.688435] BUG: unable to handle kernel NULL pointer dereference at 0000000000000060
[  209.688500] IP: [<ffffffffa0109d4e>] i915_sink_crc+0x6e/0xf0 [i915]
[  209.688577] PGD 36aba067 PUD 35d7f067 PMD 0
[  209.688613] Oops: 0000 [#1] SMP
[  209.688641] Modules linked in: fuse ip6table_filter ip6_tables ebtable_nat ebtables iTCO_wdt iTCO_vendor_support x86_pkg_temp_thermal coretemp microcode serio_raw e1000e pcspkr i2c_i801 ptp mei_me mei lpc_ich mfd_core pps_core dm_crypt i915 i2c_algo_bit crc32_pclmul drm_kms_helper crc32c_intel drm ghash_clmulni_intel video
[  209.688893] CPU: 1 PID: 1797 Comm: pm_pc8 Not tainted 3.13.0+ #118
[  209.688937] Hardware name: Intel Corporation Shark Bay Client platform/WhiteTip Mountain 1, BIOS HSWLPTU1.86C.0133.R00.1309172123 09/17/2013
[  209.689023] task: ffff88007fb4b690 ti: ffff88007d9d2000 task.ti: ffff88007d9d2000
[  209.689074] RIP: 0010:[<ffffffffa0109d4e>]  [<ffffffffa0109d4e>] i915_sink_crc+0x6e/0xf0 [i915]
[  209.689169] RSP: 0018:ffff88007d9d3e68  EFLAGS: 00010246
[  209.689205] RAX: 0000000000000000 RBX: ffff880036a03478 RCX: ffff8800366c9770
[  209.689252] RDX: ffff88014325cf38 RSI: ffff88007fb4bd08 RDI: ffff88007fb4b690
[  209.689299] RBP: ffff88007d9d3e98 R08: 0000000000000000 R09: 0000000000000000
[  209.689346] R10: 0000000000000001 R11: 0000000000000000 R12: ffff8800366c9148
[  209.689393] R13: 00000000ffffffed R14: ffff88007d9d3f50 R15: ffff880036a03478
[  209.689441] FS:  00007f5a74bc29c0(0000) GS:ffff88014f240000(0000) knlGS:0000000000000000
[  209.689494] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  209.689533] CR2: 0000000000000060 CR3: 0000000079d7e000 CR4: 00000000001407e0
[  209.689580] Stack:
[  209.689594]  0000000000001000 ffff880146083980 ffff880146083980 0000000000000000
[  209.689649]  ffff880146083980 0000000000000001 ffff88007d9d3f00 ffffffff811d0744
[  209.689702]  0000000000000046 00007fff7949fe20 ffff880036a034b8 0000000000000080
[  209.689756] Call Trace:
[  209.689778]  [<ffffffff811d0744>] seq_read+0x164/0x3e0
[  209.689816]  [<ffffffff811ab165>] vfs_read+0x95/0x160
[  209.689851]  [<ffffffff811abc79>] SyS_read+0x49/0xa0
[  209.689888]  [<ffffffff810ef64c>] ? __audit_syscall_entry+0x9c/0xf0
[  209.689933]  [<ffffffff81659412>] system_call_fastpath+0x16/0x1b

Testcase: igt/pm_pc8 (do a full run, it will fail at the debugfs-read subtest)
Signed-off-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
[danvet: Flip around NULL check for robustness.]
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Coverity points out that, if we end up in the 'failed' label, that's
precisely because we couldn't retrieve a fixed mode (ie fixed_mode is
NULL) and then "if (fixed_mode)" is always false.

Remove that dead code.
Signed-off-by: NDamien Lespiau <damien.lespiau@intel.com>
Reviewed-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

It can be corrected later and may be what was actually desired, but
generally isn't, so if we find nothing is enabled, let the core DRM fb
helper figure something out.

v2: free the array too (Jesse)

Note that this also undoes any changes in case we bail out due to hw
cloning.
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This will make the code more readable, and extensible which is needed
for upcoming feature work. Eventually, we'll do the same for init.
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

We have a couple of switch cases to compute the port value for the
VIDEO_DIP_CTL register. Replace them with a simple macro.

We do lose a few BUG() calls, but many people may consider that
an improvement.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NDamien Lespiau <damien.lespiau@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

... past the check for DRIVER_MODESET. Avoids races with userspace
opening a master and our sarea setup.

Cc: Signed-off-by: Stéphane Marchesin <marcheu@chromium.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Avoids surprises when userspace races open/closes against this.

Cc: Stéphane Marchesin <marcheu@chromium.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

We assign the sarea_priv pointer only in the dma ioctl, which is
disallowed when kernel modesetting is enabled. So this is dead code.

Cc: Stéphane Marchesin <marcheu@chromium.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

The BIOS or boot loader will generally create an initial display
configuration for us that includes some set of active pipes and
displays.  This routine tries to figure out which pipes and connectors
are active and stuffs them into the crtcs and modes array given to us by
the drm_fb_helper code.

The overall sequence is:
  intel_fbdev_init - from driver load
    intel_fbdev_init_bios - initialize the intel_fbdev using BIOS data
    drm_fb_helper_init - build fb helper structs
    drm_fb_helper_single_add_all_connectors - more fb helper structs
  intel_fbdev_initial_config - apply the config
    drm_fb_helper_initial_config - call ->probe then register_framebuffer()
        drm_setup_crtcs - build crtc config for fbdev
          intel_fb_initial_config - find active connectors etc
        drm_fb_helper_single_fb_probe - set up fbdev
          intelfb_create - re-use or alloc fb, build out fbdev structs

v2: use BIOS connector config unconditionally if possible (Daniel)
    check for crtc cloning and reject (Daniel)
    fix up comments (Daniel)
v3: use command line args and preferred modes first (Ville)
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Tested-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
[danvet: Re-add the WARN_ON for a missing encoder crtc - the state
sanitizer should take care of this. And spell-ocd the comments.]
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This allows drivers to use them in custom initial_config functions.
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Acked-by: NDave Airlie <airlied@gmail.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Just a bit of polish which I hope will help me with massaging some
internal patches to use Imre's reworked pipestat handling:
- Don't check for underrun reporting or enable pipestat interrupts
  twice.
- Frob the comments a bit.
- Do the iir PIPE_EVENT to pipe mapping explicitly with a switch. We
  only have one place which does this, so better to make it explicit.

v2: Ville noticed that I've broken the logic a bit with trying to
avoid checking whether we're interested in a given pipe twice. push
the PIPESTAT read down after we've computed the mask of interesting
bits first to avoid that duplication properly.

v3: Squash in fixups from Imre on irc.

Cc: Imre Deak <imre.deak@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NImre Deak <imre.deak@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

We want to reuse this in the fbdev initial config code independently
from any fastboot hacks. So allow a bit more flexibility.

v2: Forgot to git add ...
v3: make non-static (Jesse)
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

We want to do this early on before we try to fetch the plane config,
which depends on some of the pipe config state.

Note that the important part is that we do this before we initialize
gem, since otherwise we can't properly pre-reserve the stolen memory
for framebuffers inherited from the bios.

v2: split back out from get_plane_config change (Daniel)
    update for recent locking & reset changes (Jesse)
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>
[danvet: Explain a bit more why we need to move this.]
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

So far during driver unload we called drm_framebuffer_cleanup() for the
fbdev fb, which only removes the fb from the drm fb list regardless of
its reference count, but leaves the fb bound on an active crtc. Since
the fb's backing storage was freed this could mean we scan some random
memory content out afterwards. It's not a big issue since the fb is
allocated from stolen memory and afaik there is no other user for that
than i915. It's still cleaner to properly unbind the fb and disable the
crtc, which is what drm_framebuffer_remove() does.

Note that after

commit 88891eb1e9eca0ba619518bed31580f91e9cf84d
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Mon Feb 10 18:00:38 2014 +0100

we call drm_framebuffer_cleanup() only after dropping the last reference
on the fb, but that won't happen since we don't unbind the fb. This
results in a drm core warn about a leaked fb.
Signed-off-by: NImre Deak <imre.deak@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Reviewed-by: NDeepak S <deepak.s@intel.com>
Reviewed-by: NRodrigo Vivi <rodrigo.vivi@gmail.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Everything can be overridden by module parameters, so don't confuse the
users that are using them.

We have RC6 turned on for all platforms which support it, but Ironlake,
so the need to explain the situation is no longer pressing.
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Reviewed-by: NDeepak S <deepak.s@intel.com>
Reviewed-by: NRodrigo Vivi <rodrigo.vivi@gmail.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

It wasn't ever used by the caller anyway with the exception of what we
show in sysfs.
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Reviewed-by: NDeepak S <deepak.s@intel.com>
Reviewed-by: NRodrigo Vivi <rodrigo.vivi@gmail.com>
[danvet: Apply Deepak's suggestion.]
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

At one time, we though all future platforms would have the deeper RC6
states. As it turned out, they killed it after Ivybridge, and began
using other means to achieve the power savings (the stuff we need to get
to PC7+).

The enable function was left in a weird state of odd corner cases as a
result. Since the future is now, and we also have some insight into
what's currently the future, we have an opportunity to simplify, and
future proof the function.

NOTE: VLV will be addressed in a subsequent patch. This patch was trying
not to change functionality.

NOTE2: All callers sanitize the return value anyway, so this patch is
simply to have the code make a bit more sense.
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Reviewed-by: NDeepak S <deepak.s@intel.com>
Reviewed-by: NRodrigo Vivi <rodrigo.vivi@gmail.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

... and QUIRK_PIPEA_FORCE is not present.

I initially thought that case was impossible and just added a WARN on
it, but then I was told this case is possible due to
QUIRK_PIPEA_FORCE. So let's add a WARN that serves two purposes:
  - tell us in case we have done something wrong;
  - document the only case where we expect this.
Signed-off-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: NDamien Lespiau <damien.lespiau@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Add a nice comment explaining why we shouldn't wait for a vblank on
all cases, wait based on the HW gen, and add a comment saying we
should probably skip that wait on some of the previous HW gens.
Signed-off-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: NDamien Lespiau <damien.lespiau@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Now that we pass struct intel_crtc as an argument, we can check for
DSI inside the function, removing one more of those confusing boolean
arguments.
Signed-off-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: NDamien Lespiau <damien.lespiau@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Now that we pass struct intel_crtc as an argument, there's no need for
it.
Signed-off-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: NDamien Lespiau <damien.lespiau@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

We want to remove those 3 boolean arguments. This is the first step.
The "pipe" passed as the argument is always intel_crtc->pipe.

Also adjust the function documentation.
Signed-off-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: NDamien Lespiau <damien.lespiau@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

When I forked haswell_crtc_enable I copied all the code from
ironlake_crtc_enable. The last piece of the function contains a big
comment with a call to intel_wait_for_vblank. After this fork, we
rearranged the Haswell code so that it enables the planes as the very
last step of the modeset sequence, so we're sure that we call
intel_enable_primary_plane after the pipe is really running, so the
vblank waiting functions work as expected. I really believe this is
what fixes the problem described by the big comment, so let's give it
a try and get rid of that intel_wait_for_vblank, saving around 16ms
per modeset (and init/resume). We can always revert if needed :)
Signed-off-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>