If we want to know how many pages a VMA spans, we can use vma_pages() to
find out. We have one such invocation inside our faulthandler, so
convert it. (We have two other that want the size in bytes rather than
pages, food for future thought.)
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/20161011090656.29554-1-chris@chris-wilson.co.ukReviewed-by: NMatthew Auld <matthew.auld@intel.com>

commit 1625e7e5 ("drm/i915: make compact dma scatter lists creation
work with SWIOTLB backend") took a heavy handed approach to undo the
scatterlist compaction in the face of SWIOTLB. (The compaction hit a bug
whereby we tried to pass a segment larger than SWIOTLB could handle.) We
can be a little more intelligent and try compacting the scatterlist up
to the maximum SWIOTLB segment size (when using SWIOTLB).

v2: Tidy sg_mark_end() and cpp
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
CC: Imre Deak <imre.deak@intel.com>
CC: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Reviewed-by: NTvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161011082021.14606-2-chris@chris-wilson.co.uk

When we notice the system under memory pressure, we try to evict some
driver pages before asking the VM to shrink all caches. As a final step
in that process, we tried to evict everything, including active buffers.
This is harming ourselves, and we can mix shrinking all caches as well
as our residual buffers (after the first pass of trying to shrink just
our own buffers).
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NMichał Winiarski <michal.winiarski@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161011082021.14606-1-chris@chris-wilson.co.uk

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

We reserve space in the GuC workqueue for submitting the request in the
future. However, if we fail to construct the request, we need to give
that reserved space back to the system.

Fixes: dadd481b ("drm/i915/guc: Prepare for nonblocking execbuf submission")
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=97978Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Michał Winiarski <michal.winiarski@intel.com>
Reviewed-by: NMichał Winiarski <michal.winiarski@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161007065327.24515-4-chris@chris-wilson.co.uk

Along with the interrupt, we want to restore the fake-irq and
wait-timeout detection. If we use the breadcrumbs interface to setup the
interrupt as it wants, the auxiliary timers will also be restored.

v2: Cancel both timers as well, sanitize the IMR.

Fixes: 821ed7df ("drm/i915: Update reset path to fix incomplete requests")
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: NMika Kuoppala <mika.kuoppala@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161007065327.24515-3-chris@chris-wilson.co.uk

If we run out of enough aperture space to fit the entire object, we
fallback to trying to insert a single page. However, if that also fails,
we currently fail to userspace with an unexpected ENOSPC. (ENOSPC means
to userspace that their batch could not be fitted within the GTT.) Prior
to commit e8cb909a ("drm/i915: Fallback to single page GTT
mmappings for relocations") the approach is to fallback to using the
slow CPU relocation path in case of iomapping failure, and that is the
behaviour we need to restore.

Fixes: e8cb909a ("drm/i915: Fallback to single page GTT mmappings...")
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=98101Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161007065327.24515-2-chris@chris-wilson.co.uk

In order not to trigger hangcheck on a idle-but-waiting engine, we need
to distinguish between the pending request queue and the actual
execution queue. This is done later in "drm/i915: Enable multiple
timelines" but for now we need a temporary fix to prevent blaming the
wrong engine for a GPU hang.

(Note that this causes a temporary subtle change in how we decide when
to allow a waitboost to be re-awarded back to the waiter, the temporary
effect is that if the wait is upon the most current execution the wait
is given for free, instead of checking to see if the client stalled
itself. This will be repaired in "drm/i915: Enable multiple timelines".)

Fixes: 0a046a0e ("drm/i915: Nonblocking request submission")
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=98104Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: NMika Kuoppala <mika.kuoppala@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161007065327.24515-1-chris@chris-wilson.co.uk

Intel DZ77BH-55K board doest't have a physical VGA connector,
and yet it always detects that something is connected there.
Add it to the DMI blacklist to ignore the spurious detection
results.

Allows me to drop 'video=VGA-1:d' from my kernel cmdline.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1474881646-1326-3-git-send-email-ville.syrjala@linux.intel.comReviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Having a shadow VGA connector is useful for testing purposes. We
currently skip registering the connector on machines where the
CRT detect falsely reports it as connected. Let's instead move the
the blacklist check to the detect callback (and hpd setup) and
if we get a match we always report the connector as disconnected.
This way we get a shadow VGA connector to help with testing, while
we still avoid the user facing problems from the incorrect
detection results.

commit 8ca4013d ("CHROMIUM: i915: Add DMI override to skip CRT
initialization on ZGB") doesn't provide much in the way of details
as to why 'ACER ZGB' was added to the blacklist. Trying to trace it
further leads me to a chromeos bugreport I can't access. So based on
the fact that the commit added the
"/* Skip machines without VGA that falsely report hotplug events */"
comment, I'm going to assume that it was just spurious CRT detection.
So it should be safe to move the blacklist to just block the detection
and hpd without causing a regression on said machine.

In fact Stéphane confirmed on irc that the problem was indeed just
crappy hotplug detect:
"22:29 < marcheu> vsyrjala: the port isn't there, but the load detect is
 improperly stubbed in hw
 22:29 < marcheu> vsyrjala: so it floats"
so this change should be perfectly fine.

v2: Add irc quote from Stéphane

Cc: Duncan Laurie <dlaurie@chromium.org>
Cc: Olof Johansson <olofj@chromium.org>
Cc: Stéphane Marchesin <marcheu@chromium.org>
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1474881646-1326-2-git-send-email-ville.syrjala@linux.intel.comReviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This reverts commit 10b6ee4a.

According to [1] Dell XPS8700 VBT says 'int_crt_support 0', so thanks
to commit e4abb733 ("drm/i915: Check VBT for CRT port presence on
HSW/BDW") we no longer need to blacklist it based on DMI.

Looking through the bug report, SFUSE_STRAP based detection was
apparently also tried and failed, but the VBT based one should still
work just fine.

The commit says that the symptom was a frozen machine, but based on the
bug report it doesn't look like the CRT detection was at least directly
responsible for such a drastic outcome.

Cc: Giacomo Comes <comes@naic.edu>
References: https://bugs.freedesktop.org/show_bug.cgi?id=73559
References: http://lists.freedesktop.org/archives/intel-gfx/2014-January/038178.html [1]
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1474881646-1326-1-git-send-email-ville.syrjala@linux.intel.comReviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Sort DEV_INFO_FOR_EACH_FLAG to alphabetical order (except is_*).

v2:
- Add comments in the hope of maintaining order (Chris)

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1475664617-24541-1-git-send-email-joonas.lahtinen@linux.intel.com

Get rid of SEP_SEMICOLON and SEP_BLANK in DEV_INFO_FOR_EACH_FLAG.
Consolidate the debug output so that instead of one huge line with
"cap1,cap2,capN" each capability is split to own line and displayed
as "capN: [yes|no]" to make the dumps more historically informative.

v2:
- Do not break auto-indent by keeping semicolon after macro (Jani)
- Consolidate and use yesno() in all locations (Chris)

Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>

Allow returning "connected" or "unknown" connector status for DP branch
devices that don't have an EDID. Currently we'd claim the thing as
"disconnected" if there is no EDID.

This stuff used to broken already, I think, but it got more broken by
commit f21a2198 ("drm/i915: Splitting intel_dp_detect")

Cc: Damien Cassou <damien@cassou.me>
Cc: freedesktop.org@gp.mailgun.org
Cc: Arno <blouin.arno@gmail.com>
Cc: Shubhangi Shrivastava <shubhangi.shrivastava@intel.com>
Cc: Sivakumar Thulasimani <sivakumar.thulasimani@intel.com>
Cc: Ander Conselvan de Oliveira <conselvan2@gmail.com>
Cc: stable@vger.kernel.org
Tested-by: NArno <blouin.arno@gmail.com>
Fixes: f21a2198 ("drm/i915: Splitting intel_dp_detect")
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=83348Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1475481316-8194-2-git-send-email-ville.syrjala@linux.intel.comReviewed-by: NAnder Conselvan de Oliveira <conselvan2@gmail.com>

We can't rely on connector->status in the detect() hook if the long hpd
was already handled by the dig_port_work as that won't update
connector->status. Thus we have to defer the long hpd handling entirely
until the hotplug work runs to avoid the double long hpd handling
the "detect_done" flag is trying to prevent.

We'll start to depend on connector->status being up to date in a
following patch.

Cc: Damien Cassou <damien@cassou.me>
Cc: freedesktop.org@gp.mailgun.org
Cc: Arno <blouin.arno@gmail.com>
Cc: Shubhangi Shrivastava <shubhangi.shrivastava@intel.com>
Cc: Sivakumar Thulasimani <sivakumar.thulasimani@intel.com>
Cc: Ander Conselvan de Oliveira <conselvan2@gmail.com>
Cc: stable@vger.kernel.org
Tested-by: NArno <blouin.arno@gmail.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=83348Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1475481316-8194-1-git-send-email-ville.syrjala@linux.intel.comReviewed-by: NAnder Conselvan de Oliveira <conselvan2@gmail.com>

It is convenient to know what processes are waiting when looking at
hangcheck status in debugfs.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NMika Kuoppala <mika.kuoppala@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161004201132.21801-8-chris@chris-wilson.co.uk

Knowing where the RINGs are pointing is extremely useful in diagnosing
if the engines are executing the ringbuffers you expect - and igt may be
suppressing the usual method of looking in the GPU error state.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: NMika Kuoppala <mika.kuoppala@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161004201132.21801-7-chris@chris-wilson.co.uk

Include the position of the active request in the ring, and display that
alongside the current RING registers (on a GPU hang).
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: NMika Kuoppala <mika.kuoppala@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161004201132.21801-6-chris@chris-wilson.co.uk

Check that there was not a late recovery between us declaring the GPU
hung and processing the reset. If the GPU did recover by itself, let the
request remain on the active list and see if it hangs again!
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: NMika Kuoppala <mika.kuoppala@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161004201132.21801-5-chris@chris-wilson.co.uk

Whilst we reset the GPU, we want to prevent execlists from submitting
new work (which it does via an interrupt handler). To achieve this we
disable the irq (and drain the irq tasklet) around the reset. When we
enable it again afters, the interrupt queue should be empty and we can
reinitialise from a known state without fear of the tasklet running
concurrently.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: NMika Kuoppala <mika.kuoppala@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161004201132.21801-4-chris@chris-wilson.co.uk

After a GPU reset, we want to replay our queue of requests. However, the
GPU reset clobbered the state and we only fixup the state for the guilty
request - and engines deemed innocent we try to leave untouched so that
we recover as completely as possible. However, we need to clear the sw
tracking of the ELSP ports even for innocent requests, so move the clear
to the common path of init_hw (from reset_hw).
Reported-by: NMika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: NMika Kuoppala <mika.kuoppala@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161004201132.21801-3-chris@chris-wilson.co.uk

On Braswell, at least, we observe that the context image is written in
multiple phases. The first phase is to clear the register state, and
subsequently rewrite it. A GPU reset at the right moment can interrupt
the context update leaving it corrupt, and our update of the RING_HEAD
is not sufficient to restart the engine afterwards. To recover, we need
to reset the registers back to their original values. The context state
is lost. What we need is a better mechanism to serialise the reset with
pending flushes from the GPU.

Fixes: 821ed7df ("drm/i915: Update reset path to fix incomplete requests")
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: NMika Kuoppala <mika.kuoppala@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161004201132.21801-2-chris@chris-wilson.co.uk

Since both legacy and execlists want to populate the RING_CTL register,
share the computation of the right bits for the ring->size. We can then
stop masking errors and explicitly forbid them during creation!
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: NMika Kuoppala <mika.kuoppala@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161004201132.21801-1-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/i915_gem_execbuffer.c:432:52: warning: incorrect type in argument 1 (different address spaces)
drivers/gpu/drm/i915/i915_gem_execbuffer.c:432:52:    expected void [noderef] <asn:2>*vaddr
drivers/gpu/drm/i915/i915_gem_execbuffer.c:432:52:    got void *
drivers/gpu/drm/i915/i915_gem_execbuffer.c:477:15: warning: incorrect type in assignment (different address spaces)
drivers/gpu/drm/i915/i915_gem_execbuffer.c:477:15:    expected void *vaddr
drivers/gpu/drm/i915/i915_gem_execbuffer.c:477:15:    got void [noderef] <asn:2>*

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1475574853-4178-2-git-send-email-jani.nikula@intel.com

Fix sparse warning:

drivers/gpu/drm/i915/intel_pm.c:3970:1: warning: symbol
'skl_ddb_add_affected_planes' was not declared. Should it be static?

Fixes: 7f60e200 ("drm/i915/gen9: only add the planes actually affected by ddb changes")
Cc: Lyude <cpaul@redhat.com>
Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1475573357-30562-1-git-send-email-jani.nikula@intel.com

Instead of using bsearch library function make a local generator
macro out of it so the comparison callback can be inlined.
Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Suggested-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1475569769-31108-1-git-send-email-tvrtko.ursulin@linux.intel.com

Simply replace the linear search with the kernel's binary
search implementation. There is only six registers currently
in that table so this may not be that interesting. It adds a
function call so hopefully remains performance neutral for now.

v2: No need for manual conversion to bool for return.
    (Joonas Lahtinen)
Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>

Also verify the order at runtime. This was we can start using
binary search on it in a following patch.

v2: Add comment on the sorted array and only check it when
    debug option is enabled.

v3: Use IS_ENABLED. (Chris Wilson)
Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> (v1)
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>

We notice two identical copies of the shadow register table and
following from that removal can also unify CHV and Gen9 write
mmio functions and macros into a single implementation.

v2: Name fwtable consistently and use HAS_FWTABLE. (Joonas Lahtinen)
Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>

It is now obvious VLV, CHV and Gen9 mmio read fcuntions are
completely identical so we can remove the three copies and
just keep the newly named generic implementation.

v2: Use fwtable naming consistently. (Joonas Lahtinen)
Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>

Remove some macros which are now obviously identical.

v2: Added HAS_FWTABLE macro and simplified intel_uncore_forcewake_for_read.
    (Joonas Lahtinen)
Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>

If we store this in the uncore structure we are on a good way to
show more commonality between the per-platform implementations.

v2: Constify table pointer and correct coding style. (Chris Wilson)
v3: Rebase.
Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>

If we insert blitter forcewake domain entries in the range
table we can eliminate that special case and simplify the
code in a few macros. This will enable more unification later.
Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>

Instead of the existing linear seach, now that we have sorted
range tables, we can do a binary search on them for some
potential miniscule performance gain, but more importantly
for elegance and code size. Hopefully the perfomance gain is
sufficient to offset the function calls which were not there
before.

v2: Removed const cast away.
Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>

Sorting the tables (verified at runtime to help during
development) is another prerequisite for interesting
work which will follow.

v2:
 * Remove const away cast and improve comments. (Chris Wilson)
 * Check tables only when debug option is enabled.

v3: Use IS_ENABLED. (Chris Wilson)
Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>

Move finding the correct forcewake domains to take for
register access from code to a mapping table. This will
allow more interesting work in the following patches
and is easier to review if singled out early.
Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>

Once we know we need to take new forcewakes, that being
a slow operation, it does not make sense to inline that
code into every mmio accessor.

Move it to a separate function and save some code.

v2: Be explicit with noinline and remove stale comment.
    (Chris Wilson)
Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>

There are current places in the code, and there will be more in the
future, which iterate the forcewake domains to find out which ones
are currently active.

To save them from doing this iteration, we can cheaply keep a mask
of active domains in dev_priv->uncore.fw_domains_active.

This has no cost in terms of object size, even manages to shrink it
overall by 368 bytes on my config.
Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: "Paneri, Praveen" <praveen.paneri@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>

They are completely identical to gen6_write* ones.
Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>

Fix sparse warning:

drivers/gpu/drm/i915/intel_device_info.c:195:31: warning: Variable
length array is used.

In truth the array does have constant length, but sparse is too dumb to
realize. This is a bit ugly, but silence the warning no matter what.

Fixes: 91bedd34 ("drm/i915/bdw: Check for slice, subslice and EU count for BDW")
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1475574853-4178-1-git-send-email-jani.nikula@intel.com