Use the RING_PSMI_CTL define insted of hand rolling the register offset.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1446672017-24497-17-git-send-email-ville.syrjala@linux.intel.comReviewed-by: NChris Wilson <chris@chris-wilson.co.uk>

We have had one case where buggy csr/dmc firmware version influenced
gt side and caused a hang. Add dmc firmware loading state and
version to error state.

v2: - Rebased on top of Damien's patches
    - included fw load state
v3: include dmc info only if platform supports it (Chris)
v4: move *csr to branch scope (Chris)
v5: remove dependency to csr_state

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> (v4)
Signed-off-by: NMika Kuoppala <mika.kuoppala@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1446124879-22240-1-git-send-email-mika.kuoppala@intel.com
Tested-by: Daniel Stone <daniels@collabora.com> # SKL
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>

Change FORCEWAKE & co. reads for the error state to use I915_READ_FW().
Reading a FORCEWAKE register using a function that can frob forcewake
just seems wrong.

There is a check to skip grabbing the forcewake for accessing FORCEWAKE
in intel_uncore.c, but there's no such check for FORCEWAKE_MT. So no
idea what is currently happening with FORCEWAKE_MT reads. FORCEWAKE_VLV
is fortunately outside the forcewake range anyway, so no actual issue
with that one.

So let's just make the rule that you can't access FORCEWAKE registers with
the normal I915_READ() stuff, and we can drop the extra FORCEWAKE check
from NEEDS_FORCEWAKE(). While at it use NEEDS_FORCEWAKE() on BDW, where
it was skipped for whatever bikeshed reason that I've already forgotten.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1445517300-28173-3-git-send-email-ville.syrjala@linux.intel.comReviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>

Since we're not synchronizing the ring request list during error state capture
the request list state might change between the time the corresponding error
request list was allocated and dimensioned to the time when the ring request
list is actually captured into the error state. If this happens then do an
early exit and be aware that the captured error state might not be fully
reliable.

* v2:
- Chris Wilson: Removed WARN_ON from size check since having the error state
  request list and the live driver request list diverge like this is a
  legitimate behaviour.

- Tomas Elf: Removed update of num_request field since this made no sense. Just
  exit and move on.

* v3:
- Chris Wilson: Removed error message at the point of early exit. The user is
  not interested in any state changes happening during the error state capture,
  only in the state that we're trying to capture at the point of the error.
Signed-off-by: NTomas Elf <tomas.elf@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This reverts commit 51056723.

I somehow managed to combine a patch from Tomas Elf with a totally
unrelated commit message from Chris Wilson. Let's revert this and
reapply properly.
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>

Userspace can pass in an offset that it presumes the object is located
at. The kernel will then do its utmost to fit the object into that
location. The assumption is that userspace is handling its own object
locations (for example along with full-ppgtt) and that the kernel will
rarely have to make space for the user's requests.

v2: Fix i915_gem_evict_range() (now evict_for_vma) to handle ordinary
and fixed objects within the same batch
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: "Daniel, Thomas" <thomas.daniel@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This register was added on GEN4, by the name INSTDONE_1 whereas the GEN6
specification calls it INSTDONE_2. Keep the original name with a
platform prefix to make it clearer which INSTDONE register instance this
is. Also add a comment about the SNB alternative name.
Signed-off-by: NImre Deak <imre.deak@intel.com>
Reviewed-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

We have a bunch of INSTDONE registers for different platforms and
purposes and it's not immediately clear which instance they are just by
looking at the register name. This one was added on GEN2, where it was
the only INSTDONE register, so mark it as such.
Signed-off-by: NImre Deak <imre.deak@intel.com>
Reviewed-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

We use 3 different names to refer to the same render ring INSTDONE
register. This can be confusing when comparing two parts of the code
accessing the register via different names. Although the GEN4 version's
layout is different, we treat it the same way as the GEN7+ version, in
that we simply read it out during error capture. So remove the
duplicates and leave a comment about the GEN4 difference.

Note that there is also a GEN2 version of this register, but that's on a
different address so not handled in this patch.
Signed-off-by: NImre Deak <imre.deak@intel.com>
Reviewed-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

v2: Hide the 945 vs. rest of gen2/3 difference in the macro
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NJani Nikula <jani.nikula@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Looks like this was introduced in:
commit d1675198
Author: Alex Dai <yu.dai@intel.com>
Date:   Wed Aug 12 15:43:43 2015 +0100

    drm/i915: Integrate GuC-based command submission

This patch assumed LRC contexts and HWS layout, which is incorrect on
platforms without execlists.  This can lead to a crash in GPU error
state readout on those platforms.

I don't see a bug filed for this, but there may be one that I haven't
found.

v2: fixup offset handling for error capture fix (Dave)

Cc: Alex Dai <yu.dai@intel.com>
Reviewed-by: NDave Gordon <david.s.gordon@intel.com>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Add a common function to return "yes" or "no" string based on the
argument, and drop the local versions of it.
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

GuC-based submission is mostly the same as execlist mode, up to
intel_logical_ring_advance_and_submit(), where the context being
dispatched would be added to the execlist queue; at this point
we submit the context to the GuC backend instead.

There are, however, a few other changes also required, notably:
1.  Contexts must be pinned at GGTT addresses accessible by the GuC
    i.e. NOT in the range [0..WOPCM_SIZE), so we have to add the
    PIN_OFFSET_BIAS flag to the relevant GGTT-pinning calls.

2.  The GuC's TLB must be invalidated after a context is pinned at
    a new GGTT address.

3.  GuC firmware uses the one page before Ring Context as shared data.
    Therefore, whenever driver wants to get base address of LRC, we
    will offset one page for it. LRC_PPHWSP_PN is defined as the page
    number of LRCA.

4.  In the work queue used to pass requests to the GuC, the GuC
    firmware requires the ring-tail-offset to be represented as an
    11-bit value, expressed in QWords. Therefore, the ringbuffer
    size must be reduced to the representable range (4 pages).

v2:
    Defer adding #defines until needed [Chris Wilson]
    Rationalise type declarations [Chris Wilson]

v4:
    Squashed kerneldoc patch into here [Daniel Vetter]

v5:
    Update request->tail in code common to both GuC and execlist modes.
    Add a private version of lr_context_update(), as sharing the
        execlist version leads to race conditions when the CPU and
        the GuC both update TAIL in the context image.
    Conversion of error-captured HWS page to string must account
        for offset from start of object to actual HWS (LRC_PPHWSP_PN).

Issue: VIZ-4884
Signed-off-by: NAlex Dai <yu.dai@intel.com>
Signed-off-by: NDave Gordon <david.s.gordon@intel.com>
Reviewed-by: NTom O'Rourke <Tom.O'Rourke@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

v2: For semaphore errors, object is mapped to GGTT and offset will not
be > 4GB, print only lower 32-bits (Akash)
v3: Print gtt_offset in groups of 32-bit (Chris)

Cc: Akash Goel <akash.goel@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NMichel Thierry <michel.thierry@intel.com>
Reviewed-by: NAkash Goel <akash.goel@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

The IOMMU for Intel graphics has historically had many issues resulting
in random GPU hangs. Lets include its status when capturing the GPU hang
error state for post-mortem analysis.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Currently, we only track the last request globally across all engines.
This prevents us from issuing concurrent read requests on e.g. the RCS
and BCS engines (or more likely the render and media engines). Without
semaphores, we incur costly stalls as we synchronise between rings -
greatly impacting the current performance of Broadwell versus Haswell in
certain workloads (like video decode). With the introduction of
reference counted requests, it is much easier to track the last request
per ring, as well as the last global write request so that we can
optimise inter-engine read read requests (as well as better optimise
certain CPU waits).

v2: Fix inverted readonly condition for nonblocking waits.
v3: Handle non-continguous engine array after waits
v4: Rebase, tidy, rewrite ring list debugging
v5: Use obj->active as a bitfield, it looks cool
v6: Micro-optimise, mostly involving moving code around
v7: Fix retire-requests-upto for execlists (and multiple rq->ringbuf)
v8: Rebase
v9: Refactor i915_gem_object_sync() to allow the compiler to better
optimise it.

Benchmark: igt/gem_read_read_speed
hsw:gt3e (with semaphores):
Before: Time to read-read 1024k:		275.794µs
After:  Time to read-read 1024k:		123.260µs

hsw:gt3e (w/o semaphores):
Before: Time to read-read 1024k:		230.433µs
After:  Time to read-read 1024k:		124.593µs

bdw-u (w/o semaphores):             Before          After
Time to read-read 1x1:            26.274µs       10.350µs
Time to read-read 128x128:        40.097µs       21.366µs
Time to read-read 256x256:        77.087µs       42.608µs
Time to read-read 512x512:       281.999µs      181.155µs
Time to read-read 1024x1024:    1196.141µs     1118.223µs
Time to read-read 2048x2048:    5639.072µs     5225.837µs
Time to read-read 4096x4096:   22401.662µs    21137.067µs
Time to read-read 8192x8192:   89617.735µs    85637.681µs

Testcase: igt/gem_concurrent_blit (read-read and friends)
Cc: Lionel Landwerlin <lionel.g.landwerlin@linux.intel.com>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com> [v8]
[danvet: s/\<rq\>/req/g]
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

wa_batchbuffer is part of some error states. Make sure it
is freed.
Signed-off-by: NMika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This is mostly useful for execlists where the rings switch between
contexts (and so checking that the ring's start register matches the
context is important).
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

The faulting virtual address is >32bits and has been moved
to different registers. Add to error state and output upper
register first, in the same line for easy reconstruction of
the fault address.

v2: correct gen masking (Michel)
v3: s/TBL/TLB (Ville)
Signed-off-by: NMika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: NMichel Thierry <michel.thierry@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

While running kmemleak chasing a different memleak, I saw that the
capture_error_state function was leaking some objects, for example:

unreferenced object 0xffff8800a9b72148 (size 8192):
  comm "kworker/u16:0", pid 1499, jiffies 4295201243 (age 990.096s)
  hex dump (first 32 bytes):
    00 00 04 00 00 00 00 00 5d f4 ff ff 00 00 00 00  ........].......
    00 30 b0 01 00 00 00 00 37 00 00 00 00 00 00 00  .0......7.......
  backtrace:
    [<ffffffff811e5ae4>] create_object+0x104/0x2c0
    [<ffffffff8178f50a>] kmemleak_alloc+0x7a/0xc0
    [<ffffffff811cde4b>] __kmalloc+0xeb/0x220
    [<ffffffffa038f1d9>] kcalloc.constprop.12+0x2d/0x2f [i915]
    [<ffffffffa0316064>] i915_capture_error_state+0x3f4/0x1660 [i915]
    [<ffffffffa03207df>] i915_handle_error+0x7f/0x660 [i915]
    [<ffffffffa03210f7>] i915_hangcheck_elapsed+0x2e7/0x470 [i915]
    [<ffffffff8108d574>] process_one_work+0x144/0x490
    [<ffffffff8108dfbd>] worker_thread+0x11d/0x530
    [<ffffffff81094079>] kthread+0xc9/0xe0
    [<ffffffff817a2398>] ret_from_fork+0x58/0x90
    [<ffffffffffffffff>] 0xffffffffffffffff

The following objects are allocated in i915_gem_capture_buffers, but not
released in i915_error_state_free:
  - error->active_bo_count
  - error->pinned_bo
  - error->pinned_bo_count
  - error->active_bo[vm_count] (allocated in i915_gem_capture_vm).

The leaks were introduced by
commit 95f5301d
Author: Ben Widawsky <ben@bwidawsk.net>
Date:   Wed Jul 31 17:00:15 2013 -0700

    drm/i915: Update error capture for VMs

v2: Reuse iterator and add culprit commit details (Chris)

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NMichel Thierry <michel.thierry@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

We use the pid of the process which opened our device when
we track which was the culprit of the gpu hang. But as that
file descriptor might get inherited, we might blame the
wrong process when we record the error state.

Track process identifiers in requests to always find
the correct offender.

v2: Track only user processes (Chris)

Cc: Kenneth Graunke <kenneth@whitecape.org>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NMika Kuoppala <mika.kuoppala@intel.com>
[danvet: drop NULL check before put_pid as suggested by Chris.]
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Where there were duplicate variables for the tail, context and ring (engine)
in the gem request and the execlist queue item, use the one from the request
and remove the duplicate from the execlist queue item.

Issue: VIZ-4274

v1: Rebase
v2: Fixed build issues. Keep separate postfix & tail pointers as these are
used in different ways. Reinserted missing full tail pointer update.
Signed-off-by: NNick Hoath <nicholas.hoath@intel.com>
Reviewed-by: NThomas Daniel <thomas.daniel@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Let's be optimistic that for future platforms this will remain the same
and reorg a bit.
This reorg in if blocks instead of switch make life easier for future
platform support addition.

Cc: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: NRodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Let's be optimistic that for future platforms this will remain the same
and reorg a bit.
This reorg in if blocks instead of switch make life easier for future
platform support addition.

Cc: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: NRodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Let's be optimistic that for future platforms this will remain the same
and reorg a bit.
This reorg in if blocks instead of switch make life easier for future
platform support addition.

v2: Jani pointed out I was missing reg_830 for some gen3 platforms. So let's make
    this platforms subcases of Gen checks.

Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: NRodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Things like reliable GGTT mappings and mirrored 2d-on-3d display will need
to map objects into the same address space multiple times.

Added a GGTT view concept and linked it with the VMA to distinguish between
multiple instances per address space.

New objects and GEM functions which do not take this new view as a parameter
assume the default of zero (I915_GGTT_VIEW_NORMAL) which preserves the
previous behaviour.

This now means that objects can have multiple VMA entries so the code which
assumed there will only be one also had to be modified.

Alternative GGTT views are supposed to borrow DMA addresses from obj->pages
which is DMA mapped on first VMA instantiation and unmapped on the last one
going away.

v2:
    * Removed per view special casing in i915_gem_ggtt_prepare /
      finish_object in favour of creating and destroying DMA mappings
      on first VMA instantiation and last VMA destruction. (Daniel Vetter)
    * Simplified i915_vma_unbind which does not need to count the GGTT views.
      (Daniel Vetter)
    * Also moved obj->map_and_fenceable reset under the same check.
    * Checkpatch cleanups.

v3:
    * Only retire objects once the last VMA is unbound.

v4:
    * Keep scatter-gather table for alternative views persistent for the
      lifetime of the VMA.
    * Propagate binding errors to callers and handle appropriately.

v5:
    * Explicitly look for normal GGTT view in i915_gem_obj_bound to align
      usage in i915_gem_object_ggtt_unpin. (Michel Thierry)
    * Change to single if statement in i915_gem_obj_to_ggtt. (Michel Thierry)
    * Removed stray semi-colon in i915_gem_object_set_cache_level.

For: VIZ-4544
Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: NMichel Thierry <michel.thierry@intel.com>
[danvet: Drop hunk from i915_gem_shrink since it's just prettification
but upsets a __must_check warning.]
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

The ring member of the object structure was always updated with the
last_read_seqno member. Thus with the conversion to last_read_req, obj->ring is
now a direct copy of obj->last_read_req->ring. This makes it somewhat redundant
and potentially misleading (especially as there was no comment to explain its
purpose).

This checkin removes the redundant field. Many uses were simply testing for
non-null to see if the object is active on the GPU. Some of these have been
converted to check 'obj->active' instead. Others (where the last_read_req is
about to be used anyway) have been changed to check obj->last_read_req. The rest
simply pull the ring out from the request structure and proceed as before.

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 object structure contains the last read, write and fenced seqno values for
use in syncrhonisation operations. These have now been replaced with their
request structure counterparts.

Note that to ensure that objects do not end up with dangling pointers, the
assignments of last_*_req include reference count updates. Thus a request cannot
be freed if an object is still hanging on to it for any reason.

v2: Corrected 'last_rendering_' to 'last_read_' in a number of comments that did
not get updated when 'last_rendering_seqno' became 'last_read|write_seqno'
several millenia ago.

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>

Now unused.
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>

Spotted while reading and trying to understand how our error capture
code deals with full ppgtt.

Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>

This goes back to

commit 362b8af7
Author: Ben Widawsky <benjamin.widawsky@intel.com>
Date:   Thu Jan 30 00:19:38 2014 -0800

    drm/i915: Move per ring error state to ring_error

Spotted while reading error states.

Cc: Ben Widawsky <benjamin.widawsky@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>

for the Brothers in Triage
Signed-off-by: NMika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

If these flags are on the object level it will be more difficult to allow
for multiple VMAs per object.

v2: Simplification and cleanup after code review comments (Chris Wilson).
Signed-off-by: NTvrtko 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: NDaniel Vetter <daniel.vetter@ffwll.ch>

Reviewed-by: NRodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: NDamien Lespiau <damien.lespiau@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Reviewed-by: NRodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: NDamien Lespiau <damien.lespiau@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

v2: Rebased on top of the i915_gpu_error.c extraction.
Reviewed-by: NThomas Wood <thomas.wood@intel.com>
Signed-off-by: NDamien Lespiau <damien.lespiau@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

i915_capture_error_state can be called from all kinds of contexts, so
needs the full irqsave dance. But the other two places to grab and
release the error state are only called from process context. So
simplify them to the plaine _irq spinlock versions to clarify the
locking semantics.

Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Rather than describing an object as either "snooped or LLC", we can do
better as we should know what machine we are running on!
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Since the ringbuffer does not belong per engine anymore, we have to
make sure that we are always recording the correct ringbuffer.

TODO: This is only a small fix to keep basic error capture working, but
we need to add more information for it to be useful (e.g. dump the
context being executed).

v2: Reorder how the ringbuffer is chosen to clarify the change and
rename the variable, both changes suggested by Chris Wilson. Also,
add the TODO comment to the code, as suggested by Daniel.
Signed-off-by: NOscar Mateo <oscar.mateo@intel.com>
Reviewed-by: NDamien Lespiau <damien.lespiau@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NMika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>