Use more of the shared engine setup data for legacy engine
initialization. This time to simplify the irq initialization
code.
Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Chris Wilson <chris-wilson.co.uk>

With the unified common engine setup done, and the execlist engine
initialization loop clearly split into two phases, we can eliminate
the separate legacy engine initialization code.

v2: Fix cleanup path for legacy.
v3: Rename constructors. (Chris Wilson)
Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Chris Wilson <chris-wilson.co.uk>

Move the execlist engine setup to vfuncs so that the engine
init loop is clearly split into the mode agnostic and
specific steps.
Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Chris Wilson <chris-wilson.co.uk>

intel_lrc.c has a table of "logical rings" (meaning engines), while
intel_ringbuffer.c has separately open-coded initialisation for each
engine. We can deduplicate this somewhat by using the same first-stage
engine-setup function for both modes.

So here we expose the function that transfers information from the
static table of (all) known engines to the dev_priv->engine array of
engines available on this device (adjusting the names along the way)
and then embed calls to it in both the LRC and the legacy-mode setup.
Signed-off-by: NDave Gordon <david.s.gordon@intel.com>
Reviewed-by: Chris Wilson <chris-wilson.co.uk>
Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>

Prior to gen6 we didn't have per-ring IMR registers, which means that
since commit 61ff75ac ("drm/i915: Simplify enabling
user-interrupts with L3-remapping") we're now masking off all interrupts
when init_render_ring() gets called. That's rather rude. Let's limit
the ring IMR frobbing to machines that actually have the per-ring IMR
registers.

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Fixes: 61ff75ac ("drm/i915: Simplify enabling user-interrupts with L3-remapping")
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1468340687-3596-1-git-send-email-ville.syrjala@linux.intel.comReviewd-by: NChris Wilson <chris@chris-wilson.co.uk>

Make sure we keep kbuilder happy in all of its random configs by
providing argument names for compile-time stubs.

In file included from drivers/gpu/drm/i915/intel_dp_mst.c:27:0:
   drivers/gpu/drm/i915/i915_drv.h: In function 'i915_debugfs_register':
>> drivers/gpu/drm/i915/i915_drv.h:3612:48: error: parameter name omitted
    static inline int i915_debugfs_register(struct drm_i915_private *) {return 0;}
                                                   ^~~~~~~~~~~~~~~~
   drivers/gpu/drm/i915/i915_drv.h: In function 'i915_debugfs_unregister':
   drivers/gpu/drm/i915/i915_drv.h:3613:51: error: parameter name omitted
    static inline void i915_debugfs_unregister(struct drm_i915_private *) {}

Reported-by: 0day
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1468324529-20461-1-git-send-email-chris@chris-wilson.co.uk

In commit 7608a43d ("locking/mutexes: Use MUTEX_SPIN_ON_OWNER when
appropriate") the owner field in the mutex was updated from being
dependent upon CONFIG_SMP to using optimistic spin. Update our peek
function to suite.

Fixes:7608a43d ("locking/mutexes: Use MUTEX_SPIN_ON_OWNER...")
Reported-by: NHong Liu <hong.liu@intel.com>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1468244777-4888-1-git-send-email-chris@chris-wilson.co.ukReviewed-by: NMatthew Auld <matthew.auld@intel.com>

Now that the last couple of hacks have been removed from the runtime
powermanagement users, we can fully enable the asserts by preventing the
temptation to disable them when our code is buggy.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1468055535-19740-11-git-send-email-chris@chris-wilson.co.ukReviewed-by: NMika Kuoppala <mika.kuoppala@intel.com>

Let's ensure that we cannot run indefinitely without the hangcheck
worker being queued. We removed it from being kicked on every request
because we were kicking it a few millions times in every hangcheck
interval and only once is necessary! However, that leaves us with the
issue of what if userspace never waits for a request, or runs out of
resources, what if userspace just issues a request then spins on
BUSY_IOCTL?

Testcase: igt/gem_busy
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1468055535-19740-3-git-send-email-chris@chris-wilson.co.ukReviewed-by: NMika Kuoppala <mika.kuoppala@intel.com>

Never go to sleep waiting on the GPU without first ensuring that we will
get woken up.

We have a choice of queuing the hangcheck before every schedule() or the
first time we wakeup. In order to simply accommodate both the signaler
and the ordinary waiter, move the queuing to the common point of
enabling the irq. We lose the paranoid safety of ensuring that the
hangcheck is active before the sleep, but avoid code duplication (and
redundant hangcheck queuing).

Testcase: igt/prime_busy
Fixes: c81d4613 ("drm/i915: Convert trace-irq to the breadcrumb waiter")
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1468055535-19740-2-git-send-email-chris@chris-wilson.co.ukReviewed-by: NMika Kuoppala <mika.kuoppala@intel.com>

Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

igt/prime_vgem (and others) depends upon VGEM so automatically select it when
enabling i915 debugging.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1468059777-10205-1-git-send-email-chris@chris-wilson.co.ukReviewed-by: NMatthew Auld <matthew.auld@intel.com>

igt/pm_rpm depends upon /dev/*/msr so automatically select it when
enabling i915 debugging.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1468054147-9821-1-git-send-email-chris@chris-wilson.co.ukReviewed-by: NMatthew Auld <matthew.auld@intel.com>

One of the numerous VT-d workarounds we require is that the display
hardware reads past the end of the buffer triggering VT-d faults. This
is acknowledged in the code as being safe "since we fill the unused
portions of the GGTT with the scratch page". Alas, that is no longer
always true and so we trigger DMAR read faults.

Skylake also requires another workaround to avoid mixing VT-d and
unpopulated PTE, and so there we also need to ensure we fill unused
entries with the scratch page.
Reported-by: NMike Lothian <mike@fireburn.co.uk>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=96584
Fixes: f7770bfd ("drm/i915: Skip clearing the GGTT on full-ppgtt systems")
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: David Weinehall <david.weinehall@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1466773634-8106-1-git-send-email-chris@chris-wilson.co.ukReviewed-by: NDavid Weinehall <david.weinehall@intel.com>

Some Kabylake SKUs are going to use Kabypoint PCH.
It is mainly for Halo and DT ones.

>From our specs it doesn't seem that KBP brings
any change on the display south engine. So let's consider
this as a continuation of SunrisePoint, i.e., SPT+.

Since it is easy to get confused by a letter change:
KBL = Kabylake - CPU/GPU codename.
KBP = Kabypoint - PCH codename.
Signed-off-by: NRodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: NAnder Conselvan de Oliveira <conselvan2@gmail.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=96826
Link: http://patchwork.freedesktop.org/patch/msgid/1467418032-15167-1-git-send-email-rodrigo.vivi@intel.comSigned-off-by: NRodrigo Vivi <rodrigo.vivi@intel.com>

This patch applies WaMediaPoolStateCmdInWABB which fixes
a problem with the restoration of thread counts on resuming
from RC6.

References: HSD#2137167
Signed-off-by: NTim Gore <tim.gore@intel.com>
Reviewed-by: NArun Siluvery <arun.siluvery@linux.intel.com>
Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1467709290-5941-1-git-send-email-tim.gore@intel.com

Move the encoder cloning check to happen earlier in the modeset. The
main benefit will be that the debug output from a failed modeset will
be less confusing as output_types can not indicate an invalid
configuration during the later computation stages.

For instance, what happened to me was kms_setmode was attempting one
of its invalid cloning checks during which it asked for DP+VGA cloning
on HSW. In this case the DP .compute_config() was executed after
the FDI .compute_config() leaving the DP link clock (1.62 in this case)
in port_clock, and then later the FDI BW computation tried to use that
as the FDI link clock (which should always be 2.7). 1.62 x 2 wasn't
enough for the mode it was trying to use, and so it ended up rejecting
the modeset, not because of an invalid cloning configuration, but
because of supposedly running out of FDI bandwidth. Took me a while
to figure out what had actually happened.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1466621833-5054-12-git-send-email-ville.syrjala@linux.intel.com

With the output_types bitmask there's no need to loop through
the encoders anymore when checking for HDMI+non-HDMI cloning.

v2: Use output_types bitmask
v3: Fix the logic to really check that there are no non-HDMI encoders
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> (v2)
Link: http://patchwork.freedesktop.org/patch/msgid/1466621833-5054-11-git-send-email-ville.syrjala@linux.intel.com

has_dsi_encoder was introduced to indicate that the pipe is driving
a DSI encoder. Now that we have the output_types bitmask that can
tell us the same thing, let's just kill has_dsi_encoder.

v2: Rebase, handle BXT DSI transcoder, rewrote commit message

Cc: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1466621833-5054-10-git-send-email-ville.syrjala@linux.intel.com

INTEL_OUTPUT_DISPLAYPORT hsa been bugging me for a long time. It always
looks out of place besides INTEL_OUTPUT_EDP and INTEL_OUTPUT_DP_MST.
Let's just rename it to INTEL_OUTPUT_DP.

v2: Rebase
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NMika Kahola <mika.kahola@intel.com>
Reviewed-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1466621833-5054-9-git-send-email-ville.syrjala@linux.intel.com

A bunch of places still look for DP encoders manually. Just call
intel_crtc_has_dp_encoder(). Note that many of these places don't
look for EDP or DP_MST, but it's still fine to replace them because
* for audio we don't enable audio on eDP anyway
* the code that lack DP MST check is only for plaforms that
  don't support MST anyway

v2: Rebase
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1466621833-5054-8-git-send-email-ville.syrjala@linux.intel.com

Use the new output_types bitmask instead of has_dp_encoder.
To make it less oainlful provide a small helper
(intel_crtc_has_dp_encoder()) to do the bitsy stuff.

v2: Rebase
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1466621833-5054-7-git-send-email-ville.syrjala@linux.intel.com

Since we now have the output_types bitmaks in the crtc state, there's no
need to iterate through all the encoders to see if an LVDS or SDVO/HDMI
encoder might be present.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1466621833-5054-6-git-send-email-ville.syrjala@linux.intel.com

With the introduction of the output_types mask, intel_pipe_has_type()
and intel_pipe_will_have_type() are basically the same thing. Replace
them with a new intel_crtc_has_type() (identical to
intel_pipe_will_have_type() actually).

v2: Rebase
v3: Make intel_crtc_has_type() static inline (Chris)

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> (v2)
Link: http://patchwork.freedesktop.org/patch/msgid/1466621833-5054-5-git-send-email-ville.syrjala@linux.intel.com

Rather than looping through encoders to see which encoder types
are being driven by the pipe, add an output_types bitmask into
the crtc state and populate it prior to compute_config and during
state readout.

v2: Determine output_types before .compute_config() hooks are called
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1466621833-5054-4-git-send-email-ville.syrjala@linux.intel.com

Now that eDP encoders won't have can_mst==true, we can throw out
the encoder type checks from the MST suspend/resume paths.

Cc: Dave Airlie <airlied@redhat.com>
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1466621833-5054-3-git-send-email-ville.syrjala@linux.intel.com

If we've determined that the encoder is eDP, we shouldn't try to use MST
on it. Or at least the code doesn't seem to expect that since there are
some type==DP checks in the MST code.

Cc: Dave Airlie <airlied@redhat.com>
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NShashank Sharma <shashank.sharma@intel.com>
Reviewed-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1466621833-5054-2-git-send-email-ville.syrjala@linux.intel.com

Rather than using wait_for_atomic() when chacking for a response from
the GuC, we can get the effect of a hybrid spin/sleep wait by breaking
it into two stages. First, spin-wait for up to 10us to minimise latency
for "quick" commands; then, if that times out, sleep-wait for up 10ms
(the maximum allowed for a "slow" command).

Being able to do this depends on the recent patch
18f4b843 drm/i915: Use atomic waits for short non-atomic ones
and is similar to the hybrid approach in
1758b90e drm/i915: Use a hybrid scheme for fast register waits
(although we can't use that as-is, because that interface doesn't quite
match what we need here).
Signed-off-by: NDave Gordon <david.s.gordon@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1467815411-21756-1-git-send-email-david.s.gordon@intel.com

As we inspect both the tasklet (to check for an active bottom-half) and
set the irq-posted flag at the same time (both in the interrupt handler
and then in the bottom-halt), group those two together into the same
cacheline. (Not having total control over placement of the struct means
we can't guarantee the cacheline boundary, we need to align the kmalloc
and then each struct, but the grouping should help.)

v2: Try a couple of different names for the state touched by the user
interrupt handler.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1467805142-22219-3-git-send-email-chris@chris-wilson.co.uk

Following on from the scenario Tvrtko envisioned to explain a hard-to-hit
race with multiple first waiters, we could also then race in the
__i915_request_irq_complete() and the bottom-half may miss the vital
irq-seqno barrier and so go to sleep not noticing their seqno is
complete.

v2: unlock, not double lock the rcu_read_lock.

Fixes: 3d5564e9 ("drm/i915: Only apply one barrier after...")
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1467805142-22219-2-git-send-email-chris@chris-wilson.co.uk

After assigning ourselves as the new bottom-half, we must perform a
cursory check to prevent a missed interrupt.  Either we miss the interrupt
whilst programming the hardware, or if there was a previous waiter (for
a later seqno) they may be woken instead of us (due to the inherent race
in the unlocked read of b->tasklet in the irq handler) and so we miss the
wake up.
Spotted-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=96806
Fixes: 688e6c72 ("drm/i915: Slaughter the thundering... herd")
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1467805142-22219-1-git-send-email-chris@chris-wilson.co.uk

Since drm_i915_private is now a subclass of drm_device we do not need to
chase the drm_i915_private->dev backpointer and can instead simply
access drm_i915_private->drm directly.

   text	   data	    bss	    dec	    hex	filename
1068757	   4565	    416	1073738	 10624a	drivers/gpu/drm/i915/i915.ko
1066949	   4565	    416	1071930	 105b3a	drivers/gpu/drm/i915/i915.ko

Created by the coccinelle script:
@@
struct drm_i915_private *d;
identifier i;
@@
(
- d->dev->i
+ d->drm.i
|
- d->dev
+ &d->drm
)

and for good measure the dev_priv->dev backpointer was removed entirely.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NMatthew Auld <matthew.auld@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1467711623-2905-4-git-send-email-chris@chris-wilson.co.uk

If we have a drm_device, we have a drm_i915_private (since they are the
same).
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Imre Deak <imre.deak@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1467711623-2905-3-git-send-email-chris@chris-wilson.co.ukReviewed-by: NMatthew Auld <matthew.auld@intel.com>

As we can just directly use drm_dev->drm.dev, we do not need the
drm_dev->dev backpointer anymore and can also loose the warning about
order of __i915_printk() and our initialisation (which is now always
safe).
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Imre Deak <imre.deak@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1467711623-2905-2-git-send-email-chris@chris-wilson.co.ukReviewed-by: NMatthew Auld <matthew.auld@intel.com>

Let's reclaim a few hundred lines from i915_drv.c by splitting out the
runtime configuration of the "constant" dev_priv->info.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1467711623-2905-1-git-send-email-chris@chris-wilson.co.ukReviewed-by: NMatthew Auld <matthew.auld@intel.com>

As we only ever keep the first error state around, we can avoid some
work that can be quite intrusive if we don't record the error the second
time around. This does move the race whereby the user could discard one
error state as the second is being captured, but that race exists in the
current code and we hope that recapturing error state is only done for
debugging.

Note that as we discard the error state for simulated errors, igt that
exercise error capture continue to function.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1467618513-4966-3-git-send-email-chris@chris-wilson.co.ukReviewed-by: NMika Kuoppala <mika.kuoppala@intel.com>

Remove some redundant kernel messages as we deduce a hung GPU and
capture the error state.

v2: Fix "hang" vs "no progress" message whilst I was there
v3: s/snprintf/scnprintf/
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1467618513-4966-2-git-send-email-chris@chris-wilson.co.ukReviewed-by: NMika Kuoppala <mika.kuoppala@intel.com>

These are identical, so let's just use the same vfunc.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1467618513-4966-1-git-send-email-chris@chris-wilson.co.ukReviewed-by: NMika Kuoppala <mika.kuoppala@intel.com>

After Joonas complained about using READ_ONCE() on the only use of the
variable in the function, where the intent was to simply document that
the read was intentionally racy and unlocked, I switched the READ_ONCE()
over to lockless_dereference(). However, in linux-next that has a
stronger type-check to only allow pointers and is no longer
interchangeable with READ_ONCE(), see commit 331b6d8c
("locking/barriers: Validate lockless_dereference() is used on a pointer
type")
Reported-by: NStephen Rothwell <sfr@canb.auug.org.au>
Fixes: 67d97da3 ("drm/i915: Only start retire worker when idle")
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1467705276-707-1-git-send-email-chris@chris-wilson.co.ukReviewed-by: NMika Kuoppala <mika.kuoppala@intel.com>

Some IS_ and HAS_ macros can return any non-zero value for true.

One potential problem with that is that someone could assign
them to integers and be surprised with the result. Therefore it
is probably safer to do the conversion to 0/1 in the macros
themselves.

Luckily this does not seem to have an effect on code size.

Only one call site was getting bit by this and a patch for
that has been sent as "drm/i915/guc: Protect against HAS_GUC_*
returning true values other than one".

v2: Added some extra braces as suggested by checkpatch.
Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1467643823-9798-1-git-send-email-tvrtko.ursulin@linux.intel.com