This will allow us to read the number of dispatched compute threads
for GL_ARB_pipeline_statistics_query.
Signed-off-by: Jordan Justen <jordan.l.justen@intel.com>
Cc: Ben Widawsky <ben@bwidawsk.net>
Reviewed-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

Move it to a separate function since the main do_execbuffer function
already has so much going on.

v2:
- Move pin/unpin calls inside i915_parse_cmds() (Chris W, v4 7/7
  feedback)

Issue: VIZ-4719
Signed-off-by: Brad Volkin <bradley.d.volkin@intel.com>
Reviewed-By: Jon Bloomfield <jon.bloomfield@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

By adding a new exec_entry flag, we cleanly mark the shadow objects
as purgeable after they are on the active list.

v2:
- Move 'shadow_batch_obj->madv = I915_MADV_WILLNEED' inside _get
  fnc (danvet, from v4 6/7 feedback)

v3:
- Remove duplicate 'madv = I915_MADV_WILLNEED' (danvet, from v6 4/5)

Issue: VIZ-4719
Signed-off-by: Brad Volkin <bradley.d.volkin@intel.com>
Reviewed-By: Jon Bloomfield <jon.bloomfield@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

Previously we couldn't trust the user-supplied batch length because
it came directly from userspace (i.e. untrusted code). It would have
affected what commands software parsed without regard to what hardware
would actually execute, leaving a potential hole.

With the parser now copying the user supplied batch buffer and writing
MI_NOP commands to any space after the copied region, we can safely use
the batch length input. This should be a performance win as the actual
batch length is frequently much smaller than the allocated object size.

v2: Fix handling of non-zero batch_start_offset

Issue: VIZ-4719
Signed-off-by: Brad Volkin <bradley.d.volkin@intel.com>
Reviewed-By: Jon Bloomfield <jon.bloomfield@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

This patch sets up all of the tracking and copying necessary to
use batch pools with the command parser and dispatches the copied
(shadow) batch to the hardware.

After this patch, the parser is in 'enabling' mode.

Note that performance takes a hit from the copy in some cases
and will likely need some work. At a rough pass, the memcpy
appears to be the bottleneck. Without having done a deeper
analysis, two ideas that come to mind are:
1) Copy sections of the batch at a time, as they are reached
   by parsing. Might improve cache locality.
2) Copy only up to the userspace-supplied batch length and
   memset the rest of the buffer. Reduces the number of reads.

v2:
- Remove setting the capacity of the pool
- One global pool instead of per-ring pools
- Replace batch_obj with shadow_batch_obj and hook into eb->vmas
- Memset any space in the shadow batch beyond what gets copied
- Rebased on execlist prep refactoring

v3:
- Rebase on chained batch handling
- Squash in setting the secure dispatch flag
- Add a note about the interaction w/secure dispatch pinning
- Check for request->batch_obj == NULL in i915_gem_free_request

v4:
- Fix read domains for shadow_batch_obj
- Remove the set_to_gtt_domain call from i915_parse_cmds
- ggtt_pin/unpin in the parser block to simplify error handling
- Check USES_FULL_PPGTT before setting DISPATCH_SECURE flag
- Remove i915_gem_batch_pool_put calls

v5:
- Move 'pending_read_domains |= I915_GEM_DOMAIN_COMMAND' after
  the parser (danvet, from v4 0/7 feedback)

Issue: VIZ-4719
Signed-off-by: Brad Volkin <bradley.d.volkin@intel.com>
Reviewed-By: Jon Bloomfield <jon.bloomfield@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

This adds a small module for managing a pool of batch buffers.
The only current use case is for the command parser, as described
in the kerneldoc in the patch. The code is simple, but separating
it out makes it easier to change the underlying algorithms and to
extend to future use cases should they arise.

The interface is simple: init to create an empty pool, fini to
clean it up, get to obtain a new buffer. Note that all buffers are
expected to be inactive before cleaning up the pool.

Locking is currently based on the caller holding the struct_mutex.
We already do that in the places where we will use the batch pool
for the command parser.

v2:
- s/BUG_ON/WARN_ON/ for locking assertions
- Remove the cap on pool size
- Switch from alloc/free to init/fini

v3:
- Idiomatic looping structure in _fini
- Correct handling of purged objects
- Don't return a buffer that's too much larger than needed

v4:
- Rebased to latest -nightly

v5:
- Remove _put() function and clean up comments to match

v6:
- Move purged check inside the loop (danvet, from v4 1/7 feedback)

v7:
- Use single list instead of two. (Chris W)
- s/active_list/cache_list
- Squashed in debug patches (Chris W)
  drm/i915: Add a batch pool debugfs file

  It provides some useful information about the buffers in
  the global command parser batch pool.

  v2: rebase on global pool instead of per-ring pools
  v3: rebase

  drm/i915: Add batch pool details to i915_gem_objects debugfs

  To better account for the potentially large memory consumption
  of the batch pool.

v8:
- Keep cache in LRU order (danvet, from v6 1/5 feedback)

Issue: VIZ-4719
Signed-off-by: Brad Volkin <bradley.d.volkin@intel.com>
Reviewed-By: Jon Bloomfield <jon.bloomfield@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

After

commit a18c0af1
uthor: Thierry Reding <treding@nvidia.com>
Date:   Wed Dec 10 11:38:49 2014 +0100

    drm: Zero out DRM object memory upon cleanup

we will use the eDP encoder during destroying it. Fix this by calling
drm_encoder_cleanup() at a point when the encoder is not used any more.
This caused a NULL pointer dereference in pps_lock(), I can't see that
it caused any other problem.

All the other encoders seem to call drm_encoder_cleanup() at a safe
place.
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

I've checked that TRANS_DDI_MODE, DP_TP_CTL MST bits are identical to
HSW/BDW on SKL, as well as the long vs short HPD bits. So we have a good
chance to be working as well as prevous platforms.
Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Reviewed-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

2 pieces of code need to read out the DDI clock: the DDI encoder and the
MST encoder .get_config() vfuncs.

Until now the SKL read out code was only in the former, so let's move
the pre and post SKL logic in intel_ddi_clock_get() and this this one
everywhere.
Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Reviewed-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

LFP brighness control from the VBT block 43 indicates which
controller is used for brightness.
LFP1 brightness control method:
Bit 7-4 = This field controller number of the brightnes controller.
0 = Controller 0
1 = Controller 1
2 = Controller 2
3 = Controller 3
Others = Reserved
Bits 3-0 = This field specifies the brightness control pin to be used on the
platform.
0 = PMIC pin is used for brightness control
1 = LPSS PWM is used for brightness control
2 = Display DDI is used for brightness control
3 = CABC method to control brightness
Others = Reserved

Adding the above fields in dev_priv->vbt and corresponding changes in
parse_backlight()

v2: Jani's review comments addressed
	- Move PWM definitions to intel_bios.h
	- Moving vbt_version to intel_vbt_data
	- Rename brightness to bl_ctrl_data
	- Logging just control_pin instead of string
	- Avoid adding vbt_version in dev_priv
	- Since only DDI option is available as of now, let control pin DDI
	affect dev_priv->vbt.backlight.present

v3: Jani's review comments addressed
	- Drop control_pin
	- Use bdb->version
	- set controller to 0 instead of using control pin define
	- check controller bounds
	- remove superfluous changes in intel_parse_bios
Signed-off-by: Deepak M <m.deepak@intel.com>
Signed-off-by: Vandana Kannan <vandana.kannan@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

We were incorreectly bypassing the flush everytime which led to fifo
underrun when more than one plane is enabled.
Signed-off-by: Sonika Jindal <sonika.jindal@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Satheeshakrishna M<satheeshakrishna.m@intel.com>
Signed-off-by: Daniel 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: Thomas Daniel <thomas.daniel@intel.com>
[danvet: Add note that there's still some work left to do.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

The pipe wm parameters is not correctly updated with sprite parameters
because it copies them for each plane from plane_list to the sprite
offset in pipe wm parameters. Since plane_list also contains primary and
cursor planes, we end up updating wrong params for sprites.
Signed-off-by: Sonika Jindal <sonika.jindal@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

A short section describing background, implementation and intended usage.

v2:
    * Align section name between template and DOC comment. (Michel Thierry)

For: VIZ-4544
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Michel Thierry <michel.thierry@intel.com>
Signed-off-by: Daniel 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: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Michel 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: Daniel Vetter <daniel.vetter@ffwll.ch>

According to updated BSpec, Render/Common/media Wells register range changed.
Updating the same to match the spec and avoid extra forcewake for none
forcewake range.

v2: Update media forcewake range (Ville)
Signed-off-by: Deepak S <deepak.s@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

From now on for both DSI Ports A & C, the seq_port value has been
set to 0. seq_port value is parsed from Sequence block#53 of VBT.
So, for packets that needs to be read/write for DSI single link on
Port A and Port C will now be based on the DVO port from VBT block 2,
instead of seq_port.
Signed-off-by: Gaurav K Singh <gaurav.k.singh@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

Faster feedback to errors is always better. This is inspired by the
addition to WARN_ONs to mask/enable helpers for registers to make sure
callers have the arguments ordered correctly: Pretty much always the
arguments are static.

We use WARN_ON(1) a lot in default switch statements though where we
should always handle all cases. So add a new macro specifically for
that.

The idea to use __builtin_constant_p is from Chris Wilson.

v2: Use the ({}) gcc-ism to avoid the static inline, suggested by
Dave. My first attempt used __cond as the temp var, which is the same
used by BUILD_BUG_ON, but with inverted sense. Hilarity ensued, so
sprinkle i915 into the name.

Also use a temporary variable to only evaluate the condition once,
suggested by Damien.

v3: It's crazy but apparently 32bit gcc can't compile out the
BUILD_BUG_ON in a lot of cases and just falls over. I have no idea
why, but until clue grows just disable this nifty idea on 32bit
builds. Reported by 0-day builder.

v4: Got it all wrong, apparently its the gcc version. We need 4.9+.
Now reported by Imre.

v5: Chris suggested to add the case to MISSING_CASE for speedier
debug.

v6: Even some gcc 4.9 versions don't see through the maze, so give up
for now. Keep the skeleton and MISSING_CASE stuff though.

Cc: Imre Deak <imre.deak@intel.com>
Cc: Damien Lespiau <damien.lespiau@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Dave Gordon <david.s.gordon@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>

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

We already implement this workaround, but it was missing its name.
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Michel Thierry <michel.thierry@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

Stupid userspace (there is no evil userspace in debugfs by assumption)
might provoke a leak since we allocate the new array without holding
any locks. Drop in an unconditional kfree to deal with this - kfree
can handle NULL.

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>

Currently i915_pipe_crc_read() will drop pipe_crc->lock for the entire
duration of the copy_to_user() loop, which means it'll access
pipe_crc->entries without any protection. If another thread sneaks in
and frees pipe_crc->entries the code will oops.

Reorganize the code to hold the lock around everything except
copy_to_user(). After the copy the lock is reacquired and the the number
of available entries is rechecked.

Since this is a debug feature simplify the error handling a bit by
consuming the crc entry even if copy_to_user() would fail.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

pipe_crc->entries[] is an array so allocate with kcalloc() instead of
kzalloc().
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

Set the pipe_crc->entries pointer while holding the relevant spinlock.
Doesn't matter too much since a spurious pipe crc interrupt would then
just update one entry but later that entry would get cleared when head
and tail are both set to 0. But being a bit more paranoid doesn't hurt.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

Add the missing CRC control register value for DP port D on CHV.
Untested as I don't have a CHV machine with DP on port D.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
[danvet: Add a check to only allow DP D on chv, not vlv.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

To get stable CRCs from the DP CRC source we need to reset the
scrambler for each frame. Enable the reset feature when grabbing
CRCs for pipe C on CHV. Pipes A and B were already covered due
sharing the code with VLV.

We can safely extend PIPE_SCRAMBLE_RESET_MASK to deal with CHV since
the extra bit was MBZ on the older platforms.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

intel-gpu-tools now generates the render state with license headers and
the version of i-g-t that generated the files.

A similar patch was previously sent but wasn't actually generated with
the make target so was lacking the i-g-t revision. So here another
version before we totally forget about this.

Cc: Armin Reese <armin.c.reese@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

No functional changes.

v2 (Paulo): Rebase.
v3: Accept Daniel's suggestions:
    * remove unclear and duplicated explanation.
    * remove marketing like doc and replace by a simple one.
    * remove bdw_fbc_sw_flush documentation.
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

Due to hardware limitations on BYT, MIPI Port C DPI Enable bit
does not get set. To check whether DSI Port C was enabled in BIOS,
check the Pipe B enable bit for DSI Port C. In hardware, DSI Port C
is linked with Pipe B.

v2: Addressed review comments of Jani, Nikula
    - Used platform checks for this software workaround for BYT
Signed-off-by: Gaurav K Singh <gaurav.k.singh@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

Common bit to be used for both DSI Port A & DSI Port C.
Signed-off-by: Gaurav K Singh <gaurav.k.singh@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

DSI Pll1 is used for enabling DSI on Port C.

v2: Addressed review comments of Jani
    - Used & operator instead of == for intel_dsi->ports
Signed-off-by: Gaurav K Singh <gaurav.k.singh@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

Was missing.

Issue: VIZ-4701
Signed-off-by: Michael H. Nguyen <michael.h.nguyen@intel.com>
Reviewed-by: Jon Bloomfield <jon.bloomfield@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

No functional changes. This is just the begin of a FBC rework.

v2 (Paulo):
  - Revert intel_fbc_init() changed parameter.
  - Revert set_no_fbc_reason() rename.
  - Rebase.

Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

After a bit of irc discussion we've concluded that it would be prudent
to check that callers use the mask/enable paramters correctly. So add
a WARN_ON.

Spurred by Damien's bugfix which added _MASKED_FIELD.

v2: We use WARN_ON(1) a lot to catch default cases in switch blocks
which should always be extended. So this doesn't work really. Dunno
why gcc only started complaining when I've moved the WARN out of the
static inline helper to address a feedback from Jani.

Cc: Damien Lespiau <damien.lespiau@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>

Similar to a patch from Thomas Daniel for lrc contexts. This keeps
both sides somewhat in sync and should make Dave Gordon happy.

Note that both the wa and the golden context init code suffer a bit
from an inssuficient split into driver load and hw init code. Which
means we have a bunch of tests all over the place to check whether the
one-time initialization has been done already or not.

All that one-tim code should be moved into the one-time ring setup
code, but that's work for later.

Cc: Dave Gordon <david.s.gordon@intel.com>
Cc: Thomas Daniel <thomas.daniel@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Reviewed-by: Dave Gordon <david.s.gordon@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

Remove the function intel_output_name() that is not used anywhere.

This was partially found by using a static code analysis program called cppcheck.
Signed-off-by: Rickard Strandqvist <rickard_strandqvist@spectrumdigital.se>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

Added the request structure's 'uniq' identifier to the trace information. Also
renamed the '_complete' trace event to '_notify' as it actually happens in the
IRQ 'notify_ring()' function. The intention is to add a new '_complete' trace
event which occurs when a request structure is actually marked as complete.
However, at the moment the completion status is re-tested every time the query
is made so there isn't a completion event as such.

v2: New patch added to series.

v3: Rebased to remove completion caching as that is apparently contentious.

Change-Id: Ic9bcde67d175c6c03b96217cdcb6e4cc4aa45d67
For: VIZ-4377
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: Thomas Daniel <Thomas.Daniel@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

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: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: Thomas Daniel <Thomas.Daniel@intel.com>
Signed-off-by: Daniel 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: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: Thomas Daniel <Thomas.Daniel@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

The display related patches earlier in this series were edited during merge to
improve the request unreferencing. Specifically, the need for de-referencing at
interrupt time was removed. However, the resulting code did a 'deref(req) ; req
= NULL' sequence rather than using the 'req_assign(req, NULL)' wrapper. The two
are functionally equivalent, but using the wrapper is more consistent with all
the other places where requests are assigned.

Note that the whole point of the wrapper is that using it everywhere that
request pointers are assigned means that the reference counting is done
automatically and can't be accidentally forgotten about. Plus it allows simpler
future maintainance if the reference counting mechanisms ever need to change.

For: VIZ-4377
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>