Bspec tells us to keep bashing the PCU for up to 3ms when trying to
inform it about an upcoming change in the cdclk frequency. Currently
we only keep at it for 15*10usec (+ whatever delays gets added by
the sandybridge_pcode_read() itself). Let's change the limit to 3ms.

I decided to keep 10 usec delay per iteration for now, even though
the spec doesn't really tell us to do that.

Cc: stable@vger.kernel.org
Fixes: 5d96d8af ("drm/i915/skl: Deinit/init the display at suspend/resume")
Cc: David Weinehall <david.weinehall@intel.com>
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1468416723-23440-1-git-send-email-ville.syrjala@linux.intel.comTested-by: NDavid Weinehall <david.weinehall@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>

The obj->batch_pool_link is only inspected when traversing the batch
pool list and when on the batch pool list the object is referenced. Thus
when freeing the batch pool list, we only need to unreference the object
and do not have to worry about the obj->batch_pool_link.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1469432687-22756-5-git-send-email-chris@chris-wilson.co.ukReviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1469530913-17180-4-git-send-email-chris@chris-wilson.co.uk

Upon release of the file (i.e. the user calls close(fd)), we decouple
all objects from the client list so that we don't chase the dangling
file_priv. As we always inspect file_priv first, we only need to nullify
that pointer and can safely ignore the list_head.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1469432687-22756-4-git-send-email-chris@chris-wilson.co.ukReviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1469530913-17180-3-git-send-email-chris@chris-wilson.co.uk

list_first_entry_or_null() can generate better code than using
if (!list_empty()) {ptr = list_first_entry()) ..., so put it to use.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1469432687-22756-3-git-send-email-chris@chris-wilson.co.ukReviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1469530913-17180-2-git-send-email-chris@chris-wilson.co.uk

Since intel_engine_enable_signaling() is now only called via
fence_enable_sw_signaling(), we can rely on it to provide serialisation
and run-once for us and so make ourselves slightly simpler.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1469432687-22756-2-git-send-email-chris@chris-wilson.co.uk
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1469530913-17180-1-git-send-email-chris@chris-wilson.co.uk

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

In order to close a race with a long running hangcheck comparing a stale
interrupt counter with a just started waiter, we need to first bump the
counter as we start the fresh wait.

References: https://bugs.freedesktop.org/show_bug.cgi?id=96974Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.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/1469351421-13493-2-git-send-email-chris@chris-wilson.co.uk

During the idle-worker we disable the hangcheck and so kick any waiters
that should have been completed (since the GPU is now idle). Unlike the
hangcheck, we do not take any care to avoid the race between the irq
handler and ourselves, and so it is possible for us to declare a missed
interrupt even as the bottom-half is being scheduled to run. Let's
ignore this race to stop a potential false-positive error.

References: https://bugs.freedesktop.org/show_bug.cgi?id=96974Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.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/1469351421-13493-1-git-send-email-chris@chris-wilson.co.uk

This reverts commit b12e0ee2 ("drm/i915: Enable RC6 immediately"),
as it was never meant to be sent anywhere other than the bug report for
experimentation.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1469132179-4052-1-git-send-email-chris@chris-wilson.co.ukAcked-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

I forgot to remove these when reworking the firmware loading sequence
last year. The new sequence is that we load firmware, and if it's not
there we entirely (and permanently) fail dmc setup.
Reported-by: NDave Gordon <david.s.gordon@intel.com>
Reviewed-by: NDave Gordon <david.s.gordon@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1468505704-17391-1-git-send-email-daniel.vetter@ffwll.ch

The exit path in intel_overlay_put_image_ioctl() first unlocks the
struct_mutex, then drops its reference to 'new_bo' by calling
i915_gem_object_put(). As it isn't holding the mutex at this point,
this should be i915_gem_object_put_unlocked().

This was previously correct but got splatted in the recent
s/drm_gem_object_unreference/i915_gem_object_put/
where the _unlocked suffix was lost in this one case.

v2: don't bother fixing whitespace glitch [Chris Wilson]
    Chris can do it next time he touches gem_evict.c ;)

Fixes: f8c417cd drm/i915: Rename drm_gem_object_unreference in preparation ...
Signed-off-by: NDave Gordon <david.s.gordon@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1469122778-14416-1-git-send-email-david.s.gordon@intel.comSigned-off-by: NChris Wilson <chris@chris-wilson.co.uk>

Now that PCU communication is reasonably fast, we do not need to defer
RC6 initialisation to a workqueue.

References: https://bugs.freedesktop.org/show_bug.cgi?id=97017Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>

WaC6DisallowByGfxPause is currently applied unconditionally
but is not required in all revisions.

v2: extend application of workaround to agree with w/a
database, which differs from the HSD.

References: HSD#2133391
Signed-off-by: NTim Gore <tim.gore@intel.com>
Reviewed-by: NSagar Arun Kamble <sagar.a.kamble@intel.com>
Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1469008825-19442-1-git-send-email-tim.gore@intel.com

'ring' is an old deprecated term for a GPU engine, so we're trying to
phase out all such terminology. eb_select_ring() not only has 'ring'
(meaning engine) in its name, but it has an ugly calling convention
whereby it returns an errno and stores a pointer-to-engine indirectly
through an output parameter. As there is only one error it ever returns
(-EINVAL), we can make it return the pointer directly, and have the
caller pass back the error code -EINVAL if the pointer result is NULL.

Thus we can replace
-	ret = eb_select_ring(dev_priv, file, args, &engine);
-	if (ret)
-		return ret;
with
+	engine = eb_select_engine(dev_priv, file, args);
+	if (!engine)
+		return -EINVAL;
for increased clarity and maybe save a few cycles too.
Signed-off-by: NDave Gordon <david.s.gordon@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1469034967-15840-4-git-send-email-david.s.gordon@intel.comReviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>

'ring' is an old deprecated term for a GPU engine. Chris Wilson wants to
use the name for what is currently known as an intel_ringbuffer, but it
will be dreadfully confusing if some rings are ringbuffers but other
rings are still engines. So this patch changes the names of a bunch of
parameters called 'ring' to either 'engine' or 'engine_id' according to
what they actually are.
Signed-off-by: NDave Gordon <david.s.gordon@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1469034967-15840-3-git-send-email-david.s.gordon@intel.comReviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>

'ring' is an old deprecated term for a GPU engine. Here we make the
terminology more consistent by renaming the 'ring' parameter of lots of
macros that calculate addresses within the MMIO space of an engine.
Signed-off-by: NDave Gordon <david.s.gordon@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1469034967-15840-2-git-send-email-david.s.gordon@intel.comReviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>

Add WaDisableGatherAtSetShaderCommonSlice for all gen9 as stated
by bspec. The bspec told to put this workaround to the per ctx bb.
Initial implementation and subsequent review were done based on
bspec. Arun raised a suspicion that this would belong to indirect bb
instead and he conducted more throughout investigation on the matter
and indeed the documentation was wrong.

v2: Move to indirect_ctx wa bb, as it is correct place (Arun)

References: HSD#2135817
Cc: Arun Siluvery <arun.siluvery@linux.intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Signed-off-by: NMika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com> (v1)
Reviewed-by: NArun Siluvery <arun.siluvery@linux.intel.com>
Signed-off-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1469013973-24104-1-git-send-email-mika.kuoppala@intel.com

Add this workaround to prevent hang when in place compression
is used.

References: HSD#2135774
Cc: stable@vger.kernel.org
Signed-off-by: NMika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: NArun Siluvery <arun.siluvery@linux.intel.com>
Signed-off-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>

Rather than recomputing whether semaphores are enabled, we can do that
computation once during early initialisation as the i915.semaphores
module parameter is now read-only.

s/i915_semaphores_is_enabled/i915.semaphores/

v2: Add the state to the debug dmesg as well
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1469005202-9659-10-git-send-email-chris@chris-wilson.co.ukReviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1469017917-15134-9-git-send-email-chris@chris-wilson.co.uk

Just a different colour to better match virtual addresses elsewhere.

s/ring->virtual_start/ring->vaddr/
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1469005202-9659-9-git-send-email-chris@chris-wilson.co.ukReviewed-by: NDave Gordon <david.s.gordon@intel.com>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1469017917-15134-8-git-send-email-chris@chris-wilson.co.uk

Ringbuffers are now being written to either through LLC or WC paths, so
treating them as simply iomem is no longer adequate. However, for the
older !llc hardware, the hardware is documentated as treating the TAIL
register update as serialising, so we can relax the barriers when filling
the rings (but even if it were not, it is still an uncached register write
and so serialising anyway.).

For simplicity, let's ignore the iomem annotation.

v2: Remove iomem from ringbuffer->virtual_address
v3: And for good measure add iomem elsewhere to keep sparse happy
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com> #v2
Link: http://patchwork.freedesktop.org/patch/msgid/1469005202-9659-8-git-send-email-chris@chris-wilson.co.uk
Link: http://patchwork.freedesktop.org/patch/msgid/1469017917-15134-7-git-send-email-chris@chris-wilson.co.uk

Whilst this ultimately wraps kref_put_mutex(), our goal here is the
lockless variant, so keep the _unlocked() suffix until we need it no
more.

s/drm_gem_object_unreference_unlocked/i915_gem_object_put_unlocked/
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1469005202-9659-7-git-send-email-chris@chris-wilson.co.ukReviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1469017917-15134-6-git-send-email-chris@chris-wilson.co.uk

Ultimately wraps kref_put(), so adopt its nomenclature for consistency
with other subsystems.

s/drm_gem_object_unreference/i915_gem_object_put/
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1469005202-9659-6-git-send-email-chris@chris-wilson.co.ukReviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1469017917-15134-5-git-send-email-chris@chris-wilson.co.uk

Ultimately wraps kref_get(), so adopt its nomenclature for consistency
with other subsystems.

s/drm_gem_object_reference/i915_gem_object_get/
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1469005202-9659-5-git-send-email-chris@chris-wilson.co.ukReviewed-by: NDave Gordon <david.s.gordon@intel.com>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1469017917-15134-4-git-send-email-chris@chris-wilson.co.uk

For symmetry with a forthcoming i915_gem_object_get() and
i915_gem_object_put().
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1469005202-9659-4-git-send-email-chris@chris-wilson.co.ukReviewed-by: NDave Gordon <david.s.gordon@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1469017917-15134-3-git-send-email-chris@chris-wilson.co.uk

As these are wrappers around kref_get/kref_put() it is preferable to
follow the naming convention and use the same verb get/put in our
wrapper names for manipulating a reference to the context.

s/i915_gem_context_reference/i915_gem_context_get/
s/i915_gem_context_unreference/i915_gem_context_put/
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>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1469005202-9659-3-git-send-email-chris@chris-wilson.co.uk
Link: http://patchwork.freedesktop.org/patch/msgid/1469017917-15134-2-git-send-email-chris@chris-wilson.co.uk

Now that we derive requests from struct fence, swap over to its
nomenclature for references. It's shorter and more idiomatic across the
kernel.

s/i915_gem_request_reference/i915_gem_request_get/
s/i915_gem_request_unreference/i915_gem_request_put/
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/1469005202-9659-2-git-send-email-chris@chris-wilson.co.uk
Link: http://patchwork.freedesktop.org/patch/msgid/1469017917-15134-1-git-send-email-chris@chris-wilson.co.uk

When transitioning to the GTT or CPU domain we wait on all rendering
from i915 to complete (with the optimisation of allowing concurrent read
access by both the GPU and client). We don't yet ensure all rendering
from third parties (tracked by implicit fences on the dma-buf) is
complete. Since implicitly tracked rendering by third parties will
ignore our cache-domain tracking, we have to always wait upon rendering
from third-parties when transitioning to direct access to the backing
store. We still rely on clients notifying us of cache domain changes
(i.e. they need to move to the GTT read or write domain after doing a CPU
access before letting the third party render again).

v2:
This introduces a potential WARN_ON into i915_gem_object_free() as the
current i915_vma_unbind() calls i915_gem_object_wait_rendering(). To
hit this path we first need to render with the GPU, have a dma-buf
attached with an unsignaled fence and then interrupt the wait. It does
get fixed later in the series (when i915_vma_unbind() only waits on the
active VMA and not all, including third-party, rendering.

To offset that risk, use the __i915_vma_unbind_no_wait hack.

Testcase: igt/prime_vgem/basic-fence-read
Testcase: igt/prime_vgem/basic-fence-mmap
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1469002875-2335-8-git-send-email-chris@chris-wilson.co.uk

A foreign dma-buf does not share our cache domain tracking, and we rely
on the producer ensuring cache coherency. Marking them as being in the
CPU domain is incorrect.

v2: Add commentary about the GTT domain. This is not the best place for
it, but pending an actual overhaul of our domain tracking and explaining
each one, this comment should help the next reader...
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NMika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1469002875-2335-7-git-send-email-chris@chris-wilson.co.uk

Since commit a6f766f3 ("drm/i915: Limit ring synchronisation (sw
sempahores) RPS boosts") and commit bcafc4e3 ("drm/i915: Limit mmio
flip RPS boosts") we have limited the waitboosting for semaphores and
flips. Ideally we do not want to boost in either of these instances as no
userspace consumer is waiting upon the results (though a userspace producer
may be stalled trying to submit an execbuf - but in this case the
producer is being throttled due to the engine being saturated with
work). With the introduction of NO_WAITBOOST in the previous patch, we
can finally disable these needless boosts.
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/1469002875-2335-6-git-send-email-chris@chris-wilson.co.uk

We want to restrict waitboosting to known process contexts, where we can
track which clients are receiving waitboosts and prevent excessive power
wasting. For fence_wait() we do not have any client tracking and so that
leaves it open to abuse.

v2: Hide the IS_ERR_OR_NULL testing for special clients
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/1469002875-2335-5-git-send-email-chris@chris-wilson.co.uk

dma-buf provides a generic fence class for interoperation between
drivers. Internally we use the request structure as a fence, and so with
only a little bit of interfacing we can rebase those requests on top of
dma-buf fences. This will allow us, in the future, to pass those fences
back to userspace or between drivers.

v2: The fence_context needs to be globally unique, not just unique to
this device.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1469002875-2335-4-git-send-email-chris@chris-wilson.co.uk

Following a GPU reset upon hang, we retire all the requests and then
mark them all as complete. If we mark them as complete first, we both
keep the normal retirement order (completed first then retired) and
provide a small optimisation for concurrent lookups.
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/1469002875-2335-3-git-send-email-chris@chris-wilson.co.uk

In order to keep the memory allocated for requests reasonably tight, try
to reuse the oldest request (so long as it is completed and has no
external references) for the next allocation.

v2: Throw in a comment to hopefully make sure no one mistakes the
optimistic retirement of the oldest request for simply stealing it.
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/1469002875-2335-2-git-send-email-chris@chris-wilson.co.uk

Migrate the request operations out of the main body of i915_gem.c and
into their own C file for easier expansion.

v2: Move __i915_add_request() across as well
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Acked-by: NMika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1469002875-2335-1-git-send-email-chris@chris-wilson.co.uk

This reverts commit 041824ee.

We have latency issues that might impact the performance: #96606.
and hangs and loading issues on resume after S4: #96526.

This is also blocking a platform milestone so let's disable
this for now while we make sure we don't have any more loading
issue, or related basic hangs and it pass BAT for real in all
platofmrs.

In case BAT is wrong let's first fix BAT before re-enable it here.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=96606
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=96526
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Dave Gordon <david.s.gordon@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Stable <stable@vger.kernel.org>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Christophe Prigent <christophe.prigent@intel.com>
Signed-off-by: NRodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1468884477-30086-1-git-send-email-rodrigo.vivi@intel.com

The purpose for each MOCS entry isn't well defined atm. Defining these
is important to remove any uncertainty about the use of these entries
for example in terms of performance and GPU/CPU coherency.

Suggested by Ville.

v4:
- Rename I915_MOCS_AUTO to I915_MOCS_PTE. (Chris)

CC: Rong R Yang <rong.r.yang@intel.com>
CC: Yakui Zhao <yakui.zhao@intel.com>
CC: Ville Syrjälä <ville.syrjala@linux.intel.com>
CC: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NImre Deak <imre.deak@intel.com>
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1467383528-16142-1-git-send-email-imre.deak@intel.com

Setting a write-back cache policy in the MOCS entry definition also
implies snooping, which has a considerable overhead. This is
unexpected for a few reasons:
- From user-space's point of view since it didn't want a coherent
  surface (it didn't set the buffer as such via the set caching IOCTL).
- There is a separate MOCS entry field for snooping (which we never
  set).
- This MOCS table is about caching in (e)LLC and there is no (e)LLC on
  BXT. There is a separate table for L3 cache control.

Considering the above the current behavior of snooping looks like an
unintentional side-effect of the WB setting. Changing it to be LLC-UC
gets rid of the snooping without any ill-effects. For a coherent
surface the application would use a separate MOCS entry at index 1 and
call the set caching IOCTL to setup the PTE entries for the
corresponding buffer to be snooped. In the future we could also add a
new MOCS entry for coherent surfaces.

This resulted in 70% improvement in synthetic texturing benchmarks.

Kudos to Valtteri Rantala, Eero Tamminen and Michael T Frederick and
Ville who helped to narrow the source of problem to the kernel and to
the snooping behaviour in particular.

With a follow-up change to adjust the 3rd entry value
igt/gem_mocs_settings is passing after this change.

v2:
- Rebase on v2 of patch 1/2.
v3:
- Set the entry as LLC uncached instead of PTE-passthrough. This way
  we also keep snooping disabled, but we also make the cacheability/
  coherency setting indepent of the PTE which is managed by the
  kernel. (Chris)

CC: Rong R Yang <rong.r.yang@intel.com>
CC: Yakui Zhao <yakui.zhao@intel.com>
CC: Valtteri Rantala <valtteri.rantala@intel.com>
CC: Eero Tamminen <eero.t.tamminen@intel.com>
CC: Michael T Frederick <michael.t.frederick@intel.com>
CC: Ville Syrjälä <ville.syrjala@linux.intel.com>
CC: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NImre Deak <imre.deak@intel.com>
Acked-by: NZhao Yakui <yakui.zhao@intel.com>
Tested-by: NRong R Yang <rong.r.yang@intel.com>
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1467380406-11954-3-git-send-email-imre.deak@intel.com

Use named struct initializers for clarity. Also fix the target cache
definition to reflect its role in GEN9 onwards. On GEN8 a TC value of 0
meant ELLC but on GEN9+ it means the TC and LRU controls are taken from
the PTE.

No functional change, igt/gem_mocs_settings still passing after this
change.

v2: (Chris)
- Add back the hexa literals for the entries.
  Add note that igt/gem_mocs_settings still passes.

CC: Rong R Yang <rong.r.yang@intel.com>
CC: Yakui Zhao <yakui.zhao@intel.com>
CC: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NImre Deak <imre.deak@intel.com>
Acked-by: NZhao Yakui <yakui.zhao@intel.com>
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1467380406-11954-2-git-send-email-imre.deak@intel.com

Not sure why so much slips through when 0day is catching these. Hopefully
the much faster sphinx toolchain helps in unlazying people.
Acked-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1468612088-9721-10-git-send-email-daniel.vetter@ffwll.ch