A previous commit enabled execlists by default:

       commit 27401d12 ("drm/i915/bdw: Enable execlists by default where supported")

This allowed routine testing of execlists which exposed a regression when
resuming from suspend.  The cause was tracked down the to recent changes to the
ring init sequence:

       commit 35a57ffb ("drm/i915: Only init engines once")

During a suspend/resume cycle the hardware Context Status Buffer write pointer
is reset.  However since the recent changes to the init sequence the software CSB
read pointer is no longer reset.  This means that context status events are not
handled correctly and new contexts are not written to the ELSP, resulting in an
apparent GPU hang.

Pending further changes to the ring init code, just move the
ring->next_context_status_buffer initialization into gen8_init_common_ring to
fix this regression.

v2: Moved init into gen8_init_common_ring rather than context_enable after
feedback from Daniel Vetter.  Updated commit msg to reflect this and also cite
commits related to the regression.  Fixed bz link to correct bug.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=88096
Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Dave Gordon <david.s.gordon@intel.com>
Signed-off-by: NThomas Daniel <thomas.daniel@intel.com>
Reviewed-by: NDave Gordon <david.s.gordon@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Otherwise, new platforms without workarounds will hit this warning for
every new context created.

Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Signed-off-by: NMichel Thierry <michel.thierry@intel.com>
Reviewed-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Execlist support in the i915 driver is now considered good enough for the
feature to be enabled by default on Gen8 and later and routinely tested.
Adjusted i915 parameters structure initialization to reflect this and updated
the comment in intel_sanitize_enable_execlists().

There's still work to do before we can let the wider massive onto it,
but there's still time left before the 3.20 cutoff.

v2: Update the MODULE_PARM_DESC too.

Issue: VIZ-2020
Signed-off-by: NThomas Daniel <thomas.daniel@intel.com>
[danvet: Add note that there's still some work left to do.]
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

We consistently use the _irq_handler postfix for functions called in
hardirq context. Especially when it's a non-static function hardirq is
a crazy enough calling context to warrant this level of ocd. So rename
it.

Cc: Thomas Daniel <thomas.daniel@intel.com>
Reviewed-by: NThomas Daniel <thomas.daniel@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>

For debugging purposes, it is useful to be able to uniquely identify a given
request structure as it works its way through the system. This becomes
especially tricky once the seqno value is lazily allocated as then the request
has nothing but its pointer to identify it for much of its life.

Change-Id: Ie76b2268b940467f4cdf5a4ba6f5a54cbb96445d
For: VIZ-4377
Signed-off-by: NJohn Harrison <John.C.Harrison@Intel.com>
Reviewed-by: NThomas Daniel <Thomas.Daniel@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

There is a general theory that kzmalloc is better/safer than kmalloc, especially
for interesting data structures. This change updates the request structure
allocation to be zero filled.

This also fixes crashes in the reset code. Quoting Mika's patch:

"Clean the request structure on alloc. Otherwise we might end up
referencing uninitialized fields.  This is apparent when we try to
cleanup the preallocated request on ring reset, before any request has
been submitted to the ring.  The request->ctx is foobar and we end up
freeing the foobarness."

Note that this fixes a regression introduced in

commit 9eba5d4a
Author: John Harrison <John.C.Harrison@Intel.com>
Date:   Mon Nov 24 18:49:23 2014 +0000

    drm/i915: Ensure OLS & PLR are always in sync

References: https://bugs.freedesktop.org/show_bug.cgi?id=86959
References: https://bugs.freedesktop.org/show_bug.cgi?id=86962
References: https://bugs.freedesktop.org/show_bug.cgi?id=86992
Change-Id: I68715ef758025fab8db763941ef63bf60d7031e2
For: VIZ-4377
Signed-off-by: NJohn Harrison <John.C.Harrison@Intel.com>
Reviewed-by: NThomas Daniel <Thomas.Daniel@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

MI_STORE_DWORD_IMM length has been the same ever since gen4. Rename
the define to avoid potential confusion if someone tries to use this
on pre-gen8.

Also correct the comment on MI_MEM_VIRTUAL bit. It's present on 945,g33
and 965 only.

Cc: Oscar Mateo <oscar.mateo@intel.com>
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
[danvet: Add USE_GGTT define for g4x+ too.]
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

A previous commit introduced engine init changes:

    commit 372ee59699d9 ("drm/i915: Only init engines once")

This broke execlists as intel_lr_context_render_state_init was trying to emit
commands to the RCS for the default context before the ring->init_hw was called.

Made a new gen8_init_rcs_context function and assign in to render ring
init_context.  Moved call to intel_logical_ring_workarounds_emit into
gen8_init_rcs_context to maintain previous functionality.

Moved call to render_state_init from lr_context_deferred_create into
gen8_init_rcs_context, and modified deferred_create to call ring->init_context
for non-default contexts.

Modified i915_gem_context_enable to call ring->init_context for the default
context.

So init_context will now always be called when the hw is ready - in
i915_gem_context_enable for the default context and in lr_context_deferred_create
for other contexts.
Signed-off-by: NThomas Daniel <thomas.daniel@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Now that sanity prevails and we have the clean split between software
init and starting the engines we can drop all the "have we allocate
this struct already?" nonsense.

Execlist code could benefit quite a bit more still, but that's for
another patch.
Reviewed-by: NDave Gordon <david.s.gordon@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>

We can do this.

And now there's finally the clean split between software setup and
hardware setup I kinda wanted since multi-ring support was merged
aeons ago. It only took almost 5 years.
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>
Reviewed-by: NDave Gordon <david.s.gordon@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

With this all the ->init_hw hooks really only set up hw state needed
to start the ring, all the software state setup and memory/buffer
allocations happen beforehand.

v2: We need to call intel_init_pipe_control after the ring init since
otherwise engine->dev is NULL and it falls over. Currently that's
now after the hw ring is enabled but a) we'll be fine as long as no
one submits a batch b) this will change soon.
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>
Reviewed-by: NDave Gordon <david.s.gordon@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This is (mostly, some exceptions that need fixing) the hw setup
function which starts the ring. And not the function which allocates
all the resources.

Make this clear by giving it a better name.
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>
Reviewed-by: NDave Gordon <david.s.gordon@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

There are numerous places in the code where the driver's idea of
how much space is left in a ring is updated using the driver's
latest notions of the positions of 'head' and 'tail' for the ring.
Among them are some that update one or both of these values before
(re)doing the calculation. In particular, there are four different
places in the code where 'last_retired_head' is copied to 'head'
and then set to -1; and two of these do not have a guard to check
that it has actually been updated since last time it was consumed,
leaving the possibility that the dummy -1 can be transferred from
'last_retired_head' to 'head', causing the space calculation to
produce 'impossible' results (previously seen on Android/VLV).

This code therefore consolidates all the calculation and updating of
these values, such that there is only one place where the ring space
is updated, and it ALWAYS uses (and consumes) 'last_retired_head' if
(and ONLY if) it has been updated since the last call.
Signed-off-by: NDave Gordon <david.s.gordon@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

It makes a lot more sense (and makes future seqno -> request conversion patches
simpler) to fill in the 'ring' field of the request structure at the point of
creation rather than submission. Given that the request structure is assigned by
ring specific code and thus is locked to a ring from the start, there really is
no reason to defer this assignment.

For: VIZ-4377
Signed-off-by: NJohn Harrison <John.C.Harrison@Intel.com>
Reviewed-by: NThomas Daniel <Thomas.Daniel@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

There is no longer any need to retrieve a seqno value from an i915_add_request()
call. The calling code already knows which request structure is being processed
(it can only be ring->OLR). And as the request itself is now used in preference
to the basic seqno value, the latter is now redundant in this situation.

For: VIZ-4377
Signed-off-by: NJohn Harrison <John.C.Harrison@Intel.com>
Reviewed-by: NThomas Daniel <Thomas.Daniel@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Updated i915_wait_seqno() to take a request structure instead of a seqno value
and renamed it accordingly. Internally, it just pulls the seqno out of the
request and calls on to __wait_seqno() as before. However, all the code further
up the stack is now simplified as it can just pass the request object straight
through without having to peek inside.

For: VIZ-4377
Signed-off-by: NJohn Harrison <John.C.Harrison@Intel.com>
Reviewed-by: NThomas Daniel <Thomas.Daniel@intel.com>
[danvet: Squash in hunk from an earlier patch which was rebased
wrongly.]
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

The OLS value is now obsolete. Exactly the same value is guarateed to be always
available as PLR->seqno. Thus it is safe to remove the OLS completely. And also
to rename the PLR to OLR to keep the 'outstanding lazy ...' naming convention
valid.

For: VIZ-4377
Signed-off-by: NJohn Harrison <John.C.Harrison@Intel.com>
Reviewed-by: NThomas Daniel <Thomas.Daniel@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

The plan is to use request structures everywhere that seqno values were
previously used. This means saving pointers to structures in places that used to
be simple integers. In turn, that means that the target structure now needs much
more stringent lifetime tracking. That is, it must not be freed while some other
random object still holds a pointer to it.

To achieve this tracking, a reference count needs to be added. Whenever a
pointer to the structure is saved away, the count must be incremented and the
free must only occur when all references have been released.

For: VIZ-4377
Signed-off-by: NJohn Harrison <John.C.Harrison@Intel.com>
Reviewed-by: NThomas Daniel <Thomas.Daniel@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

The aim is to replace seqno values with request structures. A step along the way
is to switch to using the PLR in preference to the OLS. That requires the PLR to
only be valid when and only when the OLS is also valid. I.e., the two must be
kept in lock step. Then, code which was using the OLS can be safely switched
over to using the PLR instead.

For: VIZ-4377
Signed-off-by: NJohn Harrison <John.C.Harrison@Intel.com>
Reviewed-by: NThomas Daniel <Thomas.Daniel@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

The logical ring code was updating the software ring 'head' value
by reading the hardware 'HEAD' register. In LRC mode, this is not
valid as the hardware is not necessarily executing the same context
that is being processed by the software. Thus reading the h/w HEAD
could put an unrelated (undefined, effectively random) value into
the s/w 'head' -- A Bad Thing for the free space calculations.
Signed-off-by: NDave Gordon <david.s.gordon@intel.com>
Reviewed-by: NDeepak S <deepak.s@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

The request queue is per-engine, and may therefore contain requests
from several different contexts/ringbuffers. In determining which
request to wait for, this function should only consider requests
from the ringbuffer that it's checking for space, and ignore any
that it finds that belong to other contexts.
Signed-off-by: NDave Gordon <david.s.gordon@intel.com>
Reviewed-by: NDeepak S <deepak.s@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Same as with the context, pinning to GGTT regardless is harmful (it
badly fragments the GGTT and can even exhaust it).

Unfortunately, this case is also more complex than the previous one
because we need to map and access the ringbuffer in several places
along the execbuffer path (and we cannot make do by leaving the
default ringbuffer pinned, as before). Also, the context object
itself contains a pointer to the ringbuffer address that we have to
keep updated if we are going to allow the ringbuffer to move around.

v2: Same as with the context pinning, we cannot really do it during
an interrupt. Also, pin the default ringbuffers objects regardless
(makes error capture a lot easier).

v3: Rebased. Take a pin reference of the ringbuffer for each item
in the execlist request queue because the hardware may still be using
the ringbuffer after the MI_USER_INTERRUPT to notify the seqno update
is executed.  The ringbuffer must remain pinned until the context save
is complete.  No longer pin and unpin ringbuffer in
populate_lr_context() - this transient address is meaningless and the
pinning can cause a sleep while atomic.

v4: Moved ringbuffer pin and unpin into the lr_context_pin functions.
Downgraded pinning check BUG_ONs to WARN_ONs.

v5: Reinstated WARN_ONs for unexpected execlist states.  Removed unused
variable.

Issue: VIZ-4277
Signed-off-by: NOscar Mateo <oscar.mateo@intel.com>
Signed-off-by: NThomas Daniel <thomas.daniel@intel.com>
Reviewed-by: NAkash Goel <akash.goels@gmail.com>
Reviewed-by: Deepak S<deepak.s@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Up until now, we have pinned every logical ring context backing object
during creation, and left it pinned until destruction. This made my life
easier, but it's a harmful thing to do, because we cause fragmentation
of the GGTT (and, eventually, we would run out of space).

This patch makes the pinning on-demand: the backing objects of the two
contexts that are written to the ELSP are pinned right before submission
and unpinned once the hardware is done with them. The only context that
is still pinned regardless is the global default one, so that the HWS can
still be accessed in the same way (ring->status_page).

v2: In the early version of this patch, we were pinning the context as
we put it into the ELSP: on the one hand, this is very efficient because
only a maximum two contexts are pinned at any given time, but on the other
hand, we cannot really pin in interrupt time :(

v3: Use a mutex rather than atomic_t to protect pin count to avoid races.
Do not unpin default context in free_request.

v4: Break out pin and unpin into functions.  Fix style problems reported
by checkpatch

v5: Remove unpin_lock as all pinning and unpinning is done with the struct
mutex already locked.  Add WARN_ONs to make sure this is the case in future.

Issue: VIZ-4277
Signed-off-by: NOscar Mateo <oscar.mateo@intel.com>
Signed-off-by: NThomas Daniel <thomas.daniel@intel.com>
Reviewed-by: NAkash Goel <akash.goels@gmail.com>
Reviewed-by: Deepak S<deepak.s@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

No longer create a work item to clean each execlist queue item.
Instead, move retired execlist requests to a queue and clean up the
items during retire_requests.

v2: Fix legacy ring path broken during overzealous cleanup

v3: Update idle detection to take execlists queue into account

v4: Grab execlist lock when checking queue state

v5: Fix leaking requests by freeing in execlists_retire_requests.

Issue: VIZ-4274
Signed-off-by: NThomas Daniel <thomas.daniel@intel.com>
Reviewed-by: NDeepak S <deepak.s@linux.intel.com>
Reviewed-by: NAkash Goel <akash.goels@gmail.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

kmap never fails.
Spotted-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Arun Siluvery <arun.siluvery@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>

Running the driver without execlists and hence PPGTT (either aliasing or
full) isn't a supported configuration on gen9+.
Signed-off-by: NDamien Lespiau <damien.lespiau@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Write and reads following the block changed use engine specific use counters
and unless that is matched here force wake use counting goes bad. Same
force wake is attempted to be taken twice which leads to at least time outs.

NOTE: Depending on feedback from hardware designers it may not be necessary
to grab force wakes on Gen9 here. But for Gen8 it is needed due to a race
between RC6 and ELSP writes.

v2: Added blitter force wake engine and made more future proof.
    Added commit note.
Reviewed-by: NDamien Lespiau <damien.lespiau@intel.com>
Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: NDamien Lespiau <damien.lespiau@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

The LRC increased in size on gen9. Make sure we return the right
size in get_lr_context_size()

v2. Corrected the size, should be 22 pages. I unintentionally mailed out
a test patch w/ size equaling 23 pages.
Reviewed-by: NDamien Lespiau <damien.lespiau@intel.com>
Signed-off-by: NMichael H. Nguyen <michael.h.nguyen@intel.com>
Signed-off-by: NDamien Lespiau <damien.lespiau@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Following the legacy ring submission example, update the
ring->init_context() hook to support the execlist submission mode.

v2: update to use the new workaround macros and cleanup unused code.
This takes care of both bdw and chv workarounds.

v2.1: Add missing call to init_context() during deferred context creation.

v3: Split init_context (emit) in legacy/lrc modes. For lrc, get the ringbuf
from the context (Mika/Daniel).

v4: Merge init_context interfaces back, the legacy mode only needs the ring,
but the lrc mode needs the ring and context (Mika).

Issue: VIZ-4092
Issue: GMIN-3475
Change-Id: Ie3d093b2542ab0e2a44b90460533e2f979788d6c
Cc: Deepak S <deepak.s@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: NMichel Thierry <michel.thierry@intel.com>
Signed-off-by: NArun Siluvery <arun.siluvery@linux.intel.com>
Reviewed-by: NMika Kuoppala <mika.kuoppala@intel.com>
[danvet: Align function paramater lists properly.]
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Write HWS_PGA address even in execlists mode as the global hardware status
page is still required.  This address was previously uninitialized and
HWSP writes would clobber whatever buffer happened to reside at GGTT
address 0.

v2: Break out hardware status page setup into a separate function.

Issue: VIZ-2020
Signed-off-by: NThomas Daniel <thomas.daniel@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

execlists_submit_context() always returns 0, which is redundant.
And its name is inaccurate, since it actually submits (up to)
TWO contextS. So we rename it, change it to "void", and remove
the WARN_ON() testing its return value.

Change-Id: Ie225b0eca7754c6093c8b8bd15550b251b6feb82
Signed-off-by: NDave Gordon <david.s.gordon@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

If a ring failed to initialise for any reason then the error path would try to
clean up all rings including those that had not yet been allocated. The ring
clean up code did a check that the ring was valid before starting its work.
Unfortunately, that was after it had already dereferenced the ring to obtain a
dev_private pointer.
Signed-off-by: NJohn Harrison <John.C.Harrison@Intel.com>
Reviewed-by: NDamien Lespiau <damien.lespiau@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This patch fix spelling typos found in drm.xml.
It is because the file is generated from comments in
source codes, I have to fix the typos within source files.
Signed-off-by: NMasanari Iida <standby24x7@gmail.com>
Acked-by: NRandy Dunlap <rdunlap@infradead.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Yet another place that wasn't properly transformed when implementing
SOix. While at it convert the checks to WARN_ON on gen5+ (since we
don't have UMS potentially doing stupid things on those platforms).
And also add the corresponding checks to the put functions (again with
a WARN_ON) for gen5+.

v2: Drop the WARNINGS in the irq_put functions (including the existing
one for vebox), Chris convinced me that they're not that terribly
useful.

v3: Don't forget about execlist code.

Cc: Imre Deak <imre.deak@intel.com>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: "Volkin, Bradley D" <bradley.d.volkin@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>

In chv, we have two power wells Render & Media. We need to use
corresponsing forcewake count. If we dont follow this we are getting
error "*ERROR*: Timed out waiting for forcewake old ack to clear" due to
multiple entry into __vlv_force_wake_get.
Signed-off-by: NDeepak S <deepak.s@linux.intel.com>
Requested-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

The batchbuffer that sets the render context state is submitted
in a different way, and from different places.

We needed to make both the render state preparation and free functions
outside accesible, and namespace accordingly. This mess is so that all
LR, LRC and Execlists functionality can go together in intel_lrc.c: we
can fix all of this later on, once the interfaces are clear.

v2: Create a separate ctx->rcs_initialized for the Execlists case, as
suggested by Chris Wilson.
Signed-off-by: NOscar Mateo <oscar.mateo@intel.com>

v3: Setup ring status page in lr_context_deferred_create when the
default context is being created. This means that the render state
init for the default context is no longer a special case.  Execute
deferred creation of the default context at the end of
logical_ring_init to allow the render state commands to be submitted.
Fix style errors reported by checkpatch. Rebased.
Signed-off-by: NThomas Daniel <thomas.daniel@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

A previous commit broke aliasing PPGTT for lrc, resulting in a kernel oops
on boot. Add a check so that is full PPGTT is not in use the context is
populated with the aliasing PPGTT.

Issue: VIZ-4278
Signed-off-by: NThomas Daniel <thomas.daniel@intel.com>
Reviewed-by: NDamien Lespiau <damien.lespiau@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Add theory of operation notes to intel_lrc.c and comments to externally
visible functions.

v2: Add notes on logical ring context creation.

v3: Use kerneldoc.

v4: Integrate it in the DocBook template.

Signed-off-by: Thomas Daniel <thomas.daniel@intel.com> (v1)
Signed-off-by: Oscar Mateo <oscar.mateo@intel.com> (v2, v3)
Reviewed-by: NDamien Lespiau <damien.lespiau@intel.com>
[danvet: Drop hunk about render ring init function since that's not
yet merged.]
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

v2: Warn and return if LRCs are not enabled.

v3: Grab the Execlists spinlock (noticed by Daniel Vetter).
Signed-off-by: NOscar Mateo <oscar.mateo@intel.com>

v4: Lock the struct mutex for atomic state capture
Signed-off-by: NThomas Daniel <thomas.daniel@intel.com>
Reviewed-by: NDamien Lespiau <damien.lespiau@intel.com>
[danvet: Checkpatch.]
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

If we receive a storm of requests for the same context (see gem_storedw_loop_*)
we might end up iterating over too many elements in interrupt time, looking for
contexts to squash together. Instead, share the burden by giving more
intelligence to the queue function. At most, the interrupt will iterate over
three elements.
Signed-off-by: NOscar Mateo <oscar.mateo@intel.com>
Reviewed-by: NDamien Lespiau <damien.lespiau@intel.com>
[danvet: Checkpatch.]
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>