There is a possibility on gen9 hardware to miss the forcewake ack
message. The recommended workaround is to use another free
bit and toggle it until original bit is successfully acknowledged.

Some future gen9 revs might or might not fix the underlying issue but
using fallback forcewake bit dance can be considered as harmless:
without the ack timeout we never reach the fallback bit forcewake.
Thus as of now we adopt a blanket approach for all gen9 and leave
the bypassing the fallback bit approach for future patches if
corresponding hw revisions do appear.

Commit 83e33372 ("drm/i915: Increase maximum polling time to 50ms
for forcewake request/clear ack") did increase the forcewake timeout.
If the issue was a delayed ack, future work could include finding
a suitable timeout value both for primary ack and reserve toggle
to reduce the worst case latency.

v2: use bit 15, naming, comment (Chris), only wait fallback ack
v3: fix return on fallback, backoff after fallback write (Chris)
v4: udelay on first pass, grammar (Chris)
v4: s/reserve/fallback

References: HSDES #1604254524
References: https://bugs.freedesktop.org/show_bug.cgi?id=102051
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Sagar Arun Kamble <sagar.a.kamble@intel.com>
Signed-off-by: NMika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20171102094836.2506-1-mika.kuoppala@linux.intel.com

This patch adds per engine reset and recovery (TDR) support when GuC is
used to submit workloads to GPU.

In the case of i915 directly submission to ELSP, driver manages hang
detection, recovery and resubmission. With GuC submission these tasks
are shared between driver and GuC. i915 is still responsible for detecting
a hang, and when it does it only requests GuC to reset that Engine. GuC
internally manages acquiring forcewake and idling the engine before
resetting it.

Once the reset is successful, i915 takes over again and handles the
resubmission. The scheduler in i915 knows which requests are pending so
after resetting a engine, pending workloads/requests are resubmitted
again.

v2: s/i915_guc_request_engine_reset/i915_guc_reset_engine/ to match the
non-guc function names.

v3: Removed debug message about engine restarting from which request,
since the new baseline do it regardless of submission mode. (Chris)

v4: Rebase.

v5: Do not pass unnecessary reporting flags to the fw (Jeff);
tasklet_schedule(&execlists->irq_tasklet) handles the resubmit; rebase.

v6: Rename the existing reset engine function and share a similar
interface between guc and non-guc paths (Chris).
Signed-off-by: NMichel Thierry <michel.thierry@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20171031225309.10888-1-michel.thierry@intel.comReviewed-by: NJeff McGee <jeff.mcgee@intel.com>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>

intel_guc_reset sounds more like the microcontroller is the one performing
a reset, while in this case is the opposite. intel_reset_guc not only
makes it clearer, it follows the other intel_reset functions available.

v2: Print error message in English (Tvrtko).

Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Signed-off-by: NMichel Thierry <michel.thierry@intel.com>
Reviewed-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171030185616.32836-2-michel.thierry@intel.comReviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>

If GuC firmware performs an engine reset while that engine had a
preemption pending, it will set the terminated attribute bit on our
preemption stage descriptor. GuC firmware retains all pending work
items for a high-priority GuC client, unlike the normal-priority GuC
client where work items are dropped. It wants to make sure the preempt-
to-idle work doesn't run when scheduling resumes, and uses this bit to
inform its scheduler and presumably us as well. Our job is to clear it
for the next preemption after reset, otherwise that and future
preemptions will never complete. We'll just clear it every time.
Signed-off-by: NJeff McGee <jeff.mcgee@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171101221630.25086-1-jeff.mcgee@intel.comReviewed-by: NMichel Thierry <michel.thierry@intel.com>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>

For Cannonlake the number of scalers for each pipe is 2. Let's increase
the number of scalers for pipe C.

v2: Use INTEL_GEN() instead of IS_CANNONLAKE()
Signed-off-by: NMika Kahola <mika.kahola@intel.com>
Reviewed-by: NRodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: NRodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1509530930-24960-1-git-send-email-mika.kahola@intel.com

If the we think the engine is still active when we attempt to park it,
we want more details -- so dump the engine state.

References: https://bugs.freedesktop.org/show_bug.cgi?id=103479Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171027110617.31745-4-chris@chris-wilson.co.ukReviewed-by: NMika Kuoppala <mika.kuoppala@linux.intel.com>

We will want to break this down to give detailed per-engine warnings as
to why we still think we are active as we attempt to park the engines.
For the first step, just move the warning verbatim from the idle-worker
to intel_engines_park().
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20171027110617.31745-3-chris@chris-wilson.co.ukReviewed-by: NMika Kuoppala <mika.kuoppala@linux.intel.com>

We will disarm the breadcrumb interrupt if we see a user interrupt
whilst no one is waiting. This may race with the call to
intel_engine_disarm_breadcrumbs() triggering an assert that we aren't
trying to do the same job twice. Prevent this by checking that the irq
is still armed after flushing the interrupt (for the irq spinlock).

Fixes: bcbd5c33 ("drm/i915/guc: Always enable the breadcrumbs irq")
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Michał Winiarski <michal.winiarski@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171031122235.1395-1-chris@chris-wilson.co.ukReviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>

In case the object has changed tiling between calls to execbuf, we need
to check if the existing offset inside the GTT matches the new tiling
constraint. We even need to do this for "unfenced" tiled objects, where
the 3D commands use an implied fence and so the object still needs to
match the physical fence restrictions on alignment (only required for
gen2 and early gen3).

In commit 2889caa9 ("drm/i915: Eliminate lots of iterations over
the execobjects array"), the idea was to remove the second guessing and
only set the NEEDS_MAP flag when required. However, the entire check
for an unusable offset for fencing was removed and not just the
secondary check. I.e.

	/* avoid costly ping-pong once a batch bo ended up non-mappable */
        if (entry->flags & __EXEC_OBJECT_NEEDS_MAP &&
            !i915_vma_is_map_and_fenceable(vma))
                return !only_mappable_for_reloc(entry->flags);

was entirely removed as the ping-pong between execbuf passes was fixed,
but its primary purpose in forcing unaligned unfenced access to be
rebound was forgotten.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=103502
Fixes: 2889caa9 ("drm/i915: Eliminate lots of iterations over the execobjects array")
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171031103607.17836-1-chris@chris-wilson.co.ukReviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>

There is no need check if PPGTT is disabled because that not possible
in CNL. Execlists and GuC submission modes rely on at least aliasing
PPGTT and even intel_sanitize_enable_ppgtt says: "We don't allow disabling
PPGTT for gen9+ as it's a requirement for execlists, the sole mechanism
available to submit work."
Suggested-by: NDaniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: NMichel Thierry <michel.thierry@intel.com>
Reviewed-by: NDaniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Signed-off-by: NRodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171027223207.7869-1-michel.thierry@intel.com

encoder->type isn't genreally safe around DDI ports, so let's
replace some uses in the audio code with the crtc state's
output_types instead.

Actually in these cases encoder->type would work since the DP
SST case is only relevant for VLV/CHV and encoder->type==DP
is a thing on those platforms. The DP MST cases would work
as well since MST encoder->type==DP_MST always. But I think
it's best to try and minimize the encoder->type use in general
to avoid showing a bad example to people.

Cc: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171030184654.17429-2-ville.syrjala@linux.intel.comReviewed-by: NJani Nikula <jani.nikula@intel.com>

Explicitly pass the crtc and connector states into the audio
code enable/disable hooks, and plumb them all the way down.

This gets rid of almost all crtc->config and encoder->crtc
uses. The one place where we still use them is
i915_audio_component_sync_audio_rate() since that gets called from
the audio driver and we don't have explicit states around then.

Cc: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171030184654.17429-1-ville.syrjala@linux.intel.comReviewed-by: NJani Nikula <jani.nikula@intel.com>

To quote kbuild/makefiles.txt:

    cc-disable-warning checks if gcc supports a given warning and returns
    the commandline switch to disable it. This special function is needed,
    because gcc 4.4 and later accept any unknown -Wno-* option and only
    warn about it if there is another warning in the source file.

This is exactly what we were trying to achieve with cc-option -Wno-foo and
failed miserably.

Reported-by: kbuild-all@01.org
Fixes: 39bf4de8 ("drm/i915: Add -Wall -Wextra to our build, set warnings to full")
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171030172927.18158-1-chris@chris-wilson.co.ukReviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>

Eliminate the partially duplicated DDI readout code from MST, and
instead just call intel_ddi_get_config(). As a nice bonus we get
more cross checking as intel_ddi_get_config() will populate
output_types based on the actual mode of the DDI port.

Additonally intel_ddi_get_config() must be changed to get the crtc
from the passed in crtc state rather than from the encoder->crtc link.
encoder->crtc really shouldn't be used anyway.

v2: Rebased on BXT MST latency_optim fix
    Make intel_ddi_clock_get() static

Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171027193128.14483-7-ville.syrjala@linux.intel.comReviewed-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>

Pass an old crtc state to intel_ddi_post_disable() from the MST code.

Note that this crtc state won't necessaitly match the one that was
passed to intel_ddi_pre_enable() if the first stream to be enabled isn't
the last stream to be disabled. But this is fine since the states should
be identical in every important way. This does mean people frobbing
the DDI pre_enable/post_disable hooks have to pay attention in what
parts of the state they consult.

The alternative would be to inline the relevant code into the MST code.
That is actually what we used to do for pre_enable before
commit e081c846 ("drm/i915: Remove duplicate DDI enabling logic
from MST path"). For post_disable we've always called the DDI hook.

v2: Pimp up the comments explaining the MST issues

Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171027193128.14483-6-ville.syrjala@linux.intel.comReviewed-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>

We should be using the DPLL hw state we got from the current crtc state
to determine the corresponding port clock frequency rather than getting
it via the current state programmed into the DPLL.

v2: Rebase due to intel_dpll_id changes
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171027193128.14483-5-ville.syrjala@linux.intel.com

encoder->port works for FDI, and it also works for MST (regardless of
whether we're dealing with the "fake" MST encoder, or mst->primary).
So let's eliminate intel_ddi_get_encoder_port().
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171027193128.14483-4-ville.syrjala@linux.intel.com

Currently the DDI encoder->type will change at runtime depending on
what kind of hotplugs we've processed. That's quite bad since we can't
really trust that that current value of encoder->type actually matches
the type of signal we're trying to drive through it.

Let's eliminate that problem by declaring that non-eDP DDI port will
always have the encoder type as INTEL_OUTPUT_DDI. This means the code
can no longer try to distinguish DP vs. HDMI based on encoder->type.
We'll leave eDP as INTEL_OUTPUT_EDP, since it'll never change and
there's a bunch of code that relies on that value to identify eDP
encoders.

We'll introduce a new encoder .compute_output_type() hook. This allows
us to compute the full output_types before any encoder .compute_config()
hooks get called, thus those hooks can rely on output_types being
correct, which is useful for cloning on oldr platforms. For now we'll
just look at the connector type and pick the correct mode based on that.
In the future the new hook could be used to implement dynamic switching
between LS and PCON modes for LSPCON.

v2: Fix BXT/GLK PPS explosion with DSI/MST encoders
v3: Avoid the PPS warn on pure HDMI/DVI DDI encoders by checking dp.output_reg
v4: Rebase
v5: Populate output_types in .get_config() rather than in the caller
v5: Split out populating output_types in .get_config() (Maarten)

Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171027193128.14483-3-ville.syrjala@linux.intel.comReviewed-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>

Rather than having the caller of .get_config() set output_types based on
encoder->type, let's just have .get_config() itself populate
output_types. This way we are isolated from encoder->type, which won't
be useable for this purpose anyway soon (at least for DDI encoders).

Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171027193128.14483-2-ville.syrjala@linux.intel.comReviewed-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>

Starting from version 204 VBT can specify the max TMDS clock we are
allowed to use with HDMI ports. Parse that information and take it
into account when filtering modes and computing a crtc state.

Also take the opportunity to sort the platform check if ladder
from new to old.

v2: Add defines for the values into intel_vbt_defs.h (Jani)
    Don't fall back to 0 silently for unknown values (Jani)
    Skip the debug print for the 0 case (Jani)

Cc: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: NJani Nikula <jani.nikula@intel.com>
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171030145702.23662-1-ville.syrjala@linux.intel.com

The HDMI level shifter value should be 5 bits and the max data rate 3 bits.

Cc: Jani Nikula <jani.nikula@intel.com>
Reported-by: NJani Nikula <jani.nikula@intel.com>
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171027201738.3640-1-ville.syrjala@linux.intel.comReviewed-by: NJani Nikula <jani.nikula@intel.com>

Move the crtc state related 12bpc checks into hdmi_12bpc_possible()
since that one already examines other parts of the crtc state.

Note that we can drop the !force_dvi check since
crtc_state->has_hdmi_sink already accounts for that.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171026151405.30710-1-ville.syrjala@linux.intel.comReviewed-by: NChris Wilson <chris@chris-wilson.co.uk>

DP dongles may signal downstream HPD via short HPD pulses. Setting the
sink to DPMS off apparently kills the downstream HPD (at least on my
DP->VGA dongle), so skip the DPMS off for such dongles when we turn
off the port.

v2: Deal with DDI as well by moving the check into
    intel_dp_sink_dpms() (Dhinakaran)

Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Imre Deak <imre.deak@intel.com>
Cc: Pablo <pablodebiase@nanalysis.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=103472
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=99114Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171027094523.9317-1-ville.syrjala@linux.intel.comReviewed-by: NJani Nikula <jani.nikula@intel.com>

Call the DDI .pre_pll_enable() hook from the MST code so that BXT gets
the correct lane latency optimal setting applied. And we obviously need
to compute the correct value, and read it out to keep the state checker
happy.

While at it drop the useless 'encoder' parameter to
bxt_ddi_phy_calc_lane_lat_optim_mask()

Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171027134348.31190-1-ville.syrjala@linux.intel.comReviewed-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>

intel_ddi_enable_transcoder_func() already has the crtc state so we can
use that instead of the untrustworthy encoder->type.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171019133721.11794-5-ville.syrjala@linux.intel.comReviewed-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>

encoder->type is not realiable for DP/HDMI so let's switch the DPLL
selection over to using output_types.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171019133721.11794-4-ville.syrjala@linux.intel.comReviewed-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>

Eliminate intel_prepare_dp_ddi_buffers()'s reliance on the encoder->type
by passing in the crtc state.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171019133721.11794-3-ville.syrjala@linux.intel.comReviewed-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>

encoder->type isn't reliable for DP/HDMI so instead extract the correct
type from the crtc state in intel_ddi_set_pipe_settings().
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171019133721.11794-2-ville.syrjala@linux.intel.comReviewed-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>

Kasan spotted

    [IGT] gem_tiled_pread_pwrite: exiting, ret=0
    ==================================================================
    BUG: KASAN: use-after-free in __i915_gem_object_reset_page_iter+0x15c/0x170 [i915]
    Read of size 8 at addr ffff8801359da310 by task kworker/3:2/182

    CPU: 3 PID: 182 Comm: kworker/3:2 Tainted: G     U          4.14.0-rc6-CI-Custom_3340+ #1
    Hardware name: Intel Corp. Geminilake/GLK RVP1 DDR4 (05), BIOS GELKRVPA.X64.0062.B30.1708222146 08/22/2017
    Workqueue: events __i915_gem_free_work [i915]
    Call Trace:
     dump_stack+0x68/0xa0
     print_address_description+0x78/0x290
     ? __i915_gem_object_reset_page_iter+0x15c/0x170 [i915]
     kasan_report+0x23d/0x350
     __asan_report_load8_noabort+0x19/0x20
     __i915_gem_object_reset_page_iter+0x15c/0x170 [i915]
     ? i915_gem_object_truncate+0x100/0x100 [i915]
     ? lock_acquire+0x380/0x380
     __i915_gem_object_put_pages+0x30d/0x530 [i915]
     __i915_gem_free_objects+0x551/0xbd0 [i915]
     ? lock_acquire+0x13e/0x380
     __i915_gem_free_work+0x4e/0x70 [i915]
     process_one_work+0x6f6/0x1590
     ? pwq_dec_nr_in_flight+0x2b0/0x2b0
     worker_thread+0xe6/0xe90
     ? pci_mmcfg_check_reserved+0x110/0x110
     kthread+0x309/0x410
     ? process_one_work+0x1590/0x1590
     ? kthread_create_on_node+0xb0/0xb0
     ret_from_fork+0x27/0x40

    Allocated by task 1801:
     save_stack_trace+0x1b/0x20
     kasan_kmalloc+0xee/0x190
     kasan_slab_alloc+0x12/0x20
     kmem_cache_alloc+0xdc/0x2e0
     radix_tree_node_alloc.constprop.12+0x48/0x330
     __radix_tree_create+0x274/0x480
     __radix_tree_insert+0xa2/0x610
     i915_gem_object_get_sg+0x224/0x670 [i915]
     i915_gem_object_get_page+0xb5/0x1c0 [i915]
     i915_gem_pread_ioctl+0x822/0xf60 [i915]
     drm_ioctl_kernel+0x13f/0x1c0
     drm_ioctl+0x6cf/0x980
     do_vfs_ioctl+0x184/0xf30
     SyS_ioctl+0x41/0x70
     entry_SYSCALL_64_fastpath+0x1c/0xb1

    Freed by task 37:
     save_stack_trace+0x1b/0x20
     kasan_slab_free+0xaf/0x190
     kmem_cache_free+0xbf/0x340
     radix_tree_node_rcu_free+0x79/0x90
     rcu_process_callbacks+0x46d/0xf40
     __do_softirq+0x21c/0x8d3

    The buggy address belongs to the object at ffff8801359da0f0
    which belongs to the cache radix_tree_node of size 576
    The buggy address is located 544 bytes inside of
    576-byte region [ffff8801359da0f0, ffff8801359da330)
    The buggy address belongs to the page:
    page:ffffea0004d67600 count:1 mapcount:0 mapping:          (null) index:0x0 compound_mapcount: 0
    flags: 0x8000000000008100(slab|head)
    raw: 8000000000008100 0000000000000000 0000000000000000 0000000100110011
    raw: ffffea0004b52920 ffffea0004b38020 ffff88015b416a80 0000000000000000
    page dumped because: kasan: bad access detected

    Memory state around the buggy address:
     ffff8801359da200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
     ffff8801359da280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
    >ffff8801359da300: fb fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc
			     ^
     ffff8801359da380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
     ffff8801359da400: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
    ==================================================================
    Disabling lock debugging due to kernel taint

which looks like the slab containing the radixtree iter was freed as we
traversed the tree, taking the rcu read lock across the loop should
prevent that (deferring all the frees until the end).
Reported-by: NTomi Sarvela <tomi.p.sarvela@intel.com>
Fixes: d1b48c1e ("drm/i915: Replace execbuf vma ht with an idr")
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171026130032.10677-2-chris@chris-wilson.co.ukReviewed-by: NMatthew Auld <matthew.william.auld@gmail.com>

Kasan spotted

    [IGT] gem_tiled_pread_pwrite: exiting, ret=0
    ==================================================================
    BUG: KASAN: use-after-free in __i915_gem_object_reset_page_iter+0x15c/0x170 [i915]
    Read of size 8 at addr ffff8801359da310 by task kworker/3:2/182

    CPU: 3 PID: 182 Comm: kworker/3:2 Tainted: G     U          4.14.0-rc6-CI-Custom_3340+ #1
    Hardware name: Intel Corp. Geminilake/GLK RVP1 DDR4 (05), BIOS GELKRVPA.X64.0062.B30.1708222146 08/22/2017
    Workqueue: events __i915_gem_free_work [i915]
    Call Trace:
     dump_stack+0x68/0xa0
     print_address_description+0x78/0x290
     ? __i915_gem_object_reset_page_iter+0x15c/0x170 [i915]
     kasan_report+0x23d/0x350
     __asan_report_load8_noabort+0x19/0x20
     __i915_gem_object_reset_page_iter+0x15c/0x170 [i915]
     ? i915_gem_object_truncate+0x100/0x100 [i915]
     ? lock_acquire+0x380/0x380
     __i915_gem_object_put_pages+0x30d/0x530 [i915]
     __i915_gem_free_objects+0x551/0xbd0 [i915]
     ? lock_acquire+0x13e/0x380
     __i915_gem_free_work+0x4e/0x70 [i915]
     process_one_work+0x6f6/0x1590
     ? pwq_dec_nr_in_flight+0x2b0/0x2b0
     worker_thread+0xe6/0xe90
     ? pci_mmcfg_check_reserved+0x110/0x110
     kthread+0x309/0x410
     ? process_one_work+0x1590/0x1590
     ? kthread_create_on_node+0xb0/0xb0
     ret_from_fork+0x27/0x40

    Allocated by task 1801:
     save_stack_trace+0x1b/0x20
     kasan_kmalloc+0xee/0x190
     kasan_slab_alloc+0x12/0x20
     kmem_cache_alloc+0xdc/0x2e0
     radix_tree_node_alloc.constprop.12+0x48/0x330
     __radix_tree_create+0x274/0x480
     __radix_tree_insert+0xa2/0x610
     i915_gem_object_get_sg+0x224/0x670 [i915]
     i915_gem_object_get_page+0xb5/0x1c0 [i915]
     i915_gem_pread_ioctl+0x822/0xf60 [i915]
     drm_ioctl_kernel+0x13f/0x1c0
     drm_ioctl+0x6cf/0x980
     do_vfs_ioctl+0x184/0xf30
     SyS_ioctl+0x41/0x70
     entry_SYSCALL_64_fastpath+0x1c/0xb1

    Freed by task 37:
     save_stack_trace+0x1b/0x20
     kasan_slab_free+0xaf/0x190
     kmem_cache_free+0xbf/0x340
     radix_tree_node_rcu_free+0x79/0x90
     rcu_process_callbacks+0x46d/0xf40
     __do_softirq+0x21c/0x8d3

    The buggy address belongs to the object at ffff8801359da0f0
    which belongs to the cache radix_tree_node of size 576
    The buggy address is located 544 bytes inside of
    576-byte region [ffff8801359da0f0, ffff8801359da330)
    The buggy address belongs to the page:
    page:ffffea0004d67600 count:1 mapcount:0 mapping:          (null) index:0x0 compound_mapcount: 0
    flags: 0x8000000000008100(slab|head)
    raw: 8000000000008100 0000000000000000 0000000000000000 0000000100110011
    raw: ffffea0004b52920 ffffea0004b38020 ffff88015b416a80 0000000000000000
    page dumped because: kasan: bad access detected

    Memory state around the buggy address:
     ffff8801359da200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
     ffff8801359da280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
    >ffff8801359da300: fb fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc
			     ^
     ffff8801359da380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
     ffff8801359da400: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
    ==================================================================
    Disabling lock debugging due to kernel taint

which looks like the slab containing the radixtree iter was freed as we
traversed the tree, taking the rcu read lock across the loop should
prevent that (deferring all the frees until the end).
Reported-by: NTomi Sarvela <tomi.p.sarvela@intel.com>
Fixes: 96d77634 ("drm/i915: Use a radixtree for random access to the object's backing storage")
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171026130032.10677-1-chris@chris-wilson.co.ukReviewed-by: NMatthew Auld <matthew.william.auld@gmail.com>

An interesting snippet from Sandybridge's prm:

"Although a Ring Buffer can be enabled in the non-empty state, it must
not be disabled unless it is empty. Attempting to disable a Ring Buffer
in the non-empty state is UNDEFINED."

Let's avoid the undefined behaviour as we disable the rings prior to
reset and resume.

v2: Tell HEAD to catch up to TAIL (empty ring) first, then reset both to
0 (supposedly while stopped).
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: NMika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171027094311.30380-1-chris@chris-wilson.co.uk

Some minor drive-by cleanups.
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NManasi Navare <manasi.d.navare@intel.com>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171026142932.17737-2-jani.nikula@intel.com

Per my reading of the eDP spec, DP_DPCD_DISPLAY_CONTROL_CAPABLE bit in
DP_EDP_CONFIGURATION_CAP should be set if the eDP display control
registers starting at offset DP_EDP_DPCD_REV are "enabled". Currently we
check the bit before reading the registers, and DP_EDP_DPCD_REV is the
only way to detect eDP revision.

Turns out there are (likely buggy) displays that require eDP 1.4+
features, such as supported link rates and link rate select, but do not
have the bit set. Read the display control registers
unconditionally. They are supposed to read zero anyway if they are not
supported, so there should be no harm in this.

This fixes the referenced bug by enabling the eDP version check, and
thus reading of the supported link rates. The panel in question has 0 in
DP_MAX_LINK_RATE which is only supported in eDP 1.4+. Without the
supported link rates method we default to RBR which is insufficient for
the panel native mode. As a curiosity, the panel also has a bogus value
of 0x12 in DP_EDP_DPCD_REV, but that passes our check for >= DP_EDP_14
(which is 0x03).

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=103400Reported-and-tested-by: NNicolas P. <issun.artiste@gmail.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: stable@vger.kernel.org
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NManasi Navare <manasi.d.navare@intel.com>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171026142932.17737-1-jani.nikula@intel.com

The watermarks it should calculate against are the old optimal watermarks.
The currently active crtc watermarks are pure fiction, and are invalid in
case of a nonblocking modeset, page flip enabling/disabling planes or any
other reason.

When the crtc is disabled or during a modeset the intermediate watermarks
don't need to be programmed separately, and could be directly assigned
to the optimal watermarks.

Changes since v1:
- Use intel_atomic_get_old_crtc_state. (ville)
Signed-off-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NMatt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171019151341.4579-2-maarten.lankhorst@linux.intel.com
[mlankhorst: Add cc stable and bugzilla link, since previous patch doesn't fix issue by itself]
Cc: stable@vger.kernel.org #v4.8+
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=102373

The original intent was to preserve watermarks as much as possible
in intel_pipe_wm.raw_wm, and put the validated ones in intel_pipe_wm.wm.

It seems this approach is insufficient and we don't always preserve
the raw watermarks, so just use the atomic iterator we're already using
to get a const pointer to all bound planes on the crtc.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=102373Signed-off-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: stable@vger.kernel.org #v4.8+
Acked-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NMatt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171019151341.4579-1-maarten.lankhorst@linux.intel.com

During modeset cleanup on driver unload we may have a pending
hotplug work. This needs to be canceled early during the teardown
so that it does not fire after we have freed the connector.
We do this after drm_kms_helper_poll_fini(dev) since this might
trigger modeset retry work due to link retrain and before
intel_fbdev_fini() since this work requires the lock from fbdev.

If this is not done we may see something like:
DEBUG_LOCKS_WARN_ON(mutex_is_locked(lock))
 ------------[ cut here ]------------
 WARNING: CPU: 4 PID: 5010 at kernel/locking/mutex-debug.c:103 mutex_destroy+0x4e/0x60
 Modules linked in: i915(-) snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_codec_generic snd_hda_codec snd_hwdep snd_hda_core snd_pcm vgem ax88179_178
+a usbnet mii x86_pkg_temp_thermal intel_powerclamp coretemp crct10dif_pclmul crc32_pclmul ghash_clmulni_intel e1000e ptp pps_core prime_numbers i2c_hid
+[last unloaded: snd_hda_intel]
 CPU: 4 PID: 5010 Comm: drv_module_relo Tainted: G     U          4.14.0-rc3-CI-CI_DRM_3186+ #1
 Hardware name: Intel Corporation CoffeeLake Client Platform/CoffeeLake S UDIMM RVP, BIOS CNLSFWX1.R00.X104.A03.1709140524 09/14/2017
 task: ffff8803c827aa40 task.stack: ffffc90000520000
 RIP: 0010:mutex_destroy+0x4e/0x60
 RSP: 0018:ffffc90000523d58 EFLAGS: 00010292
 RAX: 000000000000002a RBX: ffff88044fbef648 RCX: 0000000000000000
 RDX: 0000000080000001 RSI: 0000000000000001 RDI: ffffffff810f0cf0
 RBP: ffffc90000523d60 R08: 0000000000000001 R09: 0000000000000001
 R10: 000000000f21cb81 R11: 0000000000000000 R12: ffff88044f71efc8
 R13: ffffffffa02b3d20 R14: ffffffffa02b3d90 R15: ffff880459b29308
 FS:  00007f5df4d6e8c0(0000) GS:ffff88045d300000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 000055ec51f00a18 CR3: 0000000451782006 CR4: 00000000003606e0
 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
 Call Trace:
  drm_fb_helper_fini+0xd9/0x130
  intel_fbdev_destroy+0x12/0x60 [i915]
  intel_fbdev_fini+0x28/0x30 [i915]
  intel_modeset_cleanup+0x45/0xa0 [i915]
  i915_driver_unload+0x92/0x180 [i915]
  i915_pci_remove+0x19/0x30 [i915]
  i915_driver_unload+0x92/0x180 [i915]
  i915_pci_remove+0x19/0x30 [i915]
  pci_device_remove+0x39/0xb0
  device_release_driver_internal+0x15d/0x220
  driver_detach+0x40/0x80
  bus_remove_driver+0x58/0xd0
  driver_unregister+0x2c/0x40
  pci_unregister_driver+0x36/0xb0
  i915_exit+0x1a/0x8b [i915]
  SyS_delete_module+0x18c/0x1e0
  entry_SYSCALL_64_fastpath+0x1c/0xb1
 RIP: 0033:0x7f5df3286287
 RSP: 002b:00007fff8e107cc8 EFLAGS: 00000246 ORIG_RAX: 00000000000000b0
 RAX: ffffffffffffffda RBX: ffffffff81493a03 RCX: 00007f5df3286287
 RDX: 0000000000000001 RSI: 0000000000000800 RDI: 0000564c7be02e48
 RBP: ffffc90000523f88 R08: 0000000000000000 R09: 0000000000000080
 R10: 00007f5df4d6e8c0 R11: 0000000000000246 R12: 0000000000000000
 R13: 00007fff8e107eb0 R14: 0000000000000000 R15: 0000000000000000
Or a GPF like:

 general protection fault: 0000 [#1] PREEMPT SMP
 Modules linked in: i915(-) snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_codec_generic snd_hda_codec snd_hwdep snd_hda_core snd_pcm vgem ax88179_178
+a usbnet mii x86_pkg_temp_thermal intel_powerclamp coretemp crct10dif_pclmul crc32_pclmul ghash_clmulni_intel e1000e ptp pps_core prime_numbers i2c_hid
+[last unloaded: snd_hda_intel]
 CPU: 0 PID: 82 Comm: kworker/0:1 Tainted: G     U  W       4.14.0-rc3-CI-CI_DRM_3186+ #1
 Hardware name: Intel Corporation CoffeeLake Client Platform/CoffeeLake S UDIMM RVP, BIOS CNLSFWX1.R00.X104.A03.1709140524 09/14/2017
 Workqueue: events intel_dp_modeset_retry_work_fn [i915]
 task: ffff88045a5caa40 task.stack: ffffc90000378000
 RIP: 0010:drm_setup_crtcs+0x143/0xbf0
 RSP: 0018:ffffc9000037bd20 EFLAGS: 00010202
 RAX: 6b6b6b6b6b6b6b6b RBX: 0000000000000002 RCX: 0000000000000001
 RDX: 0000000000000001 RSI: 0000000000000780 RDI: 00000000ffffffff
 RBP: ffffc9000037bdb8 R08: 0000000000000001 R09: 0000000000000001
 R10: 0000000000000780 R11: 0000000000000000 R12: 0000000000000002
 R13: ffff88044fbef4e8 R14: 0000000000000780 R15: 0000000000000438
 FS:  0000000000000000(0000) GS:ffff88045d200000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 000055ec51ee5168 CR3: 000000044c89d003 CR4: 00000000003606f0
 Call Trace:
  drm_fb_helper_hotplug_event.part.18+0x7e/0xc0
  drm_fb_helper_hotplug_event+0x1a/0x20
  intel_fbdev_output_poll_changed+0x1a/0x20 [i915]
  drm_kms_helper_hotplug_event+0x27/0x30
  intel_dp_modeset_retry_work_fn+0x77/0x80 [i915]
  process_one_work+0x233/0x660
  worker_thread+0x206/0x3b0
  kthread+0x152/0x190
  ? process_one_work+0x660/0x660
  ? kthread_create_on_node+0x40/0x40
  ret_from_fork+0x27/0x40
 Code: 06 00 00 45 8b 45 20 31 db 45 31 e4 45 85 c0 0f 8e 91 06 00 00 44 8b 75 94 44 8b 7d 90 49 8b 45 28 49 63 d4 44 89 f6 41 83 c4 01 <48> 8b 04 d0 44
+89 fa 48 8b 38 48 8b 87 a8 01 00 00 ff 50 20 01
 RIP: drm_setup_crtcs+0x143/0xbf0 RSP: ffffc9000037bd20
 ---[ end trace 08901ff1a77d30c7 ]---

v2:
* Rename it to intel_hpd_poll_fini() and call drm_kms_helper_fini() inside it
as the first step before cancel work (Chris Wilson)
* Add GPF trace in commit message and make the function static (Maarten Lankhorst)
Suggested-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Suggested-by: NChris Wilson <chris@chris-wilson.co.uk>
Fixes: 9301397a ("drm/i915: Implement Link Rate fallback on Link training failure")
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tony Cheng <tony.cheng@amd.com>
Cc: Harry Wentland <Harry.wentland@amd.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Daniel Vetter <daniel.vetter@intel.com>
Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
Cc: Manasi Navare <manasi.d.navare@intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: NManasi Navare <manasi.d.navare@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1509054720-25325-1-git-send-email-manasi.d.navare@intel.comReviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>

Recently W=1 on gcc-7.2 (-Wunused-const-variable) caught a regression
that had been lurking for 6 months, so lets try enabling the full set of
warnings for CI builds. This means more patches will be rejected early
that contain trivial and sometimes not so trivial bugs. However, our
code does not yet compile cleanly with W=1, so we have to apply a filter
to the set of warnings until we can eliminate the mistakes. It also
means that developers will have to be running the full gamut of gcc to
ensure that as warnings come and go with gcc updates, we have the CI
build prepared.

v2: Use fine-grained -Wno overrides. Inside the makefile, we can
specify CFLAGS on a per-object level, which allows us to limit the scope
of any particular warning override.
v3: Place per-file overrides after the main enabling block.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Tomi Sarvela <tomi.p.sarvela@intel.com>
Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Acked-by: NTomi Sarvela <tomi.p.sarvela@intel.com>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171024181547.27889-1-chris@chris-wilson.co.ukAcked-by: NJani Nikula <jani.nikula@intel.com>

Knowing the RING_MODE flags is useful for checking the state of the
engine, such as whether the CS is idle after trying to stop the engines
before reset.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171026115048.20144-1-chris@chris-wilson.co.ukReviewed-by: NMika Kuoppala <mika.kuoppala@linux.intel.com>

Waiting for DMA status register can be done with dedicated function.
Lets use it as additional bonus will be smaller driver footprint.
Signed-off-by: NMichal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20171024105056.43276-1-michal.wajdeczko@intel.com

Pretty similar to what we have on execlists.
We're reusing most of the GEM code, however, due to GuC quirks we need a
couple of extra bits.
Preemption is implemented as GuC action, and actions can be pretty slow.
Because of that, we're using a mutex to serialize them. Since we're
requesting preemption from the tasklet, the task of creating a workitem
and wrapping it in GuC action is delegated to a worker.

To distinguish that preemption has finished, we're using additional
piece of HWSP, and since we're not getting context switch interrupts,
we're also adding a user interrupt.

The fact that our special preempt context has completed unfortunately
doesn't mean that we're ready to submit new work. We also need to wait
for GuC to finish its own processing.

v2: Don't compile out the wait for GuC, handle workqueue flush on reset,
no need for ordered workqueue, put on a reviewer hat when looking at my own
patches (Chris)
Move struct work around in intel_guc, move user interruput outside of
conditional (Michał)
Keep ring around rather than chase though intel_context

v3: Extract WA for flushing ggtt writes to a helper (Chris)
Keep work_struct in intel_guc rather than engine (Michał)
Use ordered workqueue for inject_preempt worker to avoid GuC quirks.

v4: Drop now unused INTEL_GUC_PREEMPT_OPTION_IMMEDIATE (Daniele)
Drop stray newlines, use container_of for intel_guc in worker,
check for presence of workqueue when flushing it, rather than
enable_guc_submission modparam, reorder preempt postprocessing (Chris)

v5: Make wq NULL after destroying it

v6: Swap struct guc_preempt_work members (Michał)
Signed-off-by: NMichał Winiarski <michal.winiarski@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Jeff McGee <jeff.mcgee@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Oscar Mateo <oscar.mateo@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20171026133558.19580-1-michal.winiarski@intel.com