The gt wedged could be triggered by missing guc firmware file, HW not
working, etc. Once triggered, it means all gt usage is dead, therefore we
can't enable pxp under this fatal error condition.

v2: Updated commit message.
v3: Updated return code check.
Signed-off-by: Zhanjun Dong <zhanjun.dong@intel.com>
Reviewed-by: Alan Previn <alan.previn.teres.alexis@intel.com>
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231113224953.378534-1-zhanjun.dong@intel.com

Debugging PXP issues can't even begin without understanding precedding
sequence of important events. Add drm_dbg into the most important PXP
events.

 v5 : - rebase.
 v4 : - rebase.
 v3 : - move gt_dbg to after mutex block in function
        i915_gsc_proxy_component_bind. (Vivaik)
 v2 : - remove __func__ since drm_dbg covers that (Jani).
      - add timeout dbg of the restart from front-end (Alan).
Signed-off-by: Alan Previn <alan.previn.teres.alexis@intel.com>
Reviewed-by: Vivaik Balasubrawmanian <vivaik.balasubrawmanian@intel.com>
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231122191523.58379-1-alan.previn.teres.alexis@intel.com

This workaround has been dropped from all DG2 variants in the latest
workaround database update.
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Gustavo Sousa <gustavo.sousa@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231127190043.4099109-2-matthew.d.roper@intel.com

ATS-M device ID update.

BSpec: 44477
Signed-off-by: Haridhar Kalvala <haridhar.kalvala@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231120113731.1570589-1-haridhar.kalvala@intel.com

Track every intel_gt_pm_get() until its corresponding release in
intel_gt_pm_put() by returning a cookie to the caller for acquire that
must be passed by on released. When there is an imbalance, we can see who
either tried to free a stale wakeref, or who forgot to free theirs.

v2: track recently added calls in gen8_ggtt_bind_get_ce and
    destroyed_worker_func
Signed-off-by: Andrzej Hajda <andrzej.hajda@intel.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231030-ref_tracker_i915-v1-2-006fe6b96421@intel.com

Beside reusing existing code, the main advantage of ref_tracker is
tracking per instance of wakeref. It allows also to catch double
put.
On the other side we lose information about the first acquire and
the last release, but the advantages outweigh it.
Signed-off-by: Andrzej Hajda <andrzej.hajda@intel.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231030-ref_tracker_i915-v1-1-006fe6b96421@intel.com

The GSC CS is not exposed to the user, so we skipped assigning a uabi
class number for it. However, the trace logs use the uabi class and
instance to identify the engine, so leaving uabi class unset makes the
GSC CS show up as the RCS in those logs.

Given that the engine is not exposed to the user, we can't add a new
case in the uabi enum, so we insted internally define a kernel
internal class as -1.

At the same time remove special handling for the name and complete
the uabi_classes array so internal class is automatically correctly
assigned.

Engine will show as 65535:0 other0 in the logs/traces which should
be unique enough.

v2:
 * Fix uabi class u8 vs u16 type confusion.
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Fixes: 194babe2 ("drm/i915/mtl: don't expose GSC command streamer to the user")
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Alan Previn <alan.previn.teres.alexis@intel.com>
Cc: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231116084456.291533-1-tvrtko.ursulin@linux.intel.com

__rcu annotation is needed to avoid the sparse warnings such as:

  .../i915_drm_client.c:92:9: sparse: sparse: incompatible types in comparison expression (different address spaces):
  .../i915_drm_client.c:92:9: sparse:    struct list_head [noderef] __rcu *
  .../i915_drm_client.c:92:9: sparse:    struct list_head *
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Fixes: 96885303 ("drm/i915: Implement fdinfo memory stats printing")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202311110610.h0m6ydI5-lkp@intel.com/
Cc: Andi Shyti <andi.shyti@linux.intel.com>
Cc: Aravind Iddamsetty <aravind.iddamsetty@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231113085457.199053-2-tvrtko.ursulin@linux.intel.com

There is no need to return anything in the version which was merged and
also the implementation of the !CONFIG_PROC_FS wasn't returning anything,
causing a build failure there.
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Fixes: e4ae85e3 ("drm/i915: Add ability for tracking buffer objects per client")
Cc: Aravind Iddamsetty <aravind.iddamsetty@intel.com>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202311110104.8TlHVxUI-lkp@intel.com/Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231113085457.199053-1-tvrtko.ursulin@linux.intel.com

Commit 78cc55e0 ("drm/i915/mcr: Hold GT forcewake during steering
operations") introduced the workaround which was in early stages. With a
valid lineage number update Workaround for future tracking.

Cc: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Radhakrishna Sripada <radhakrishna.sripada@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231116212511.1760446-1-radhakrishna.sripada@intel.com

The workaround database was just updated to extend this workaround to
DG2-G11 (whereas previously it applied only to G10 and G12).
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Gustavo Sousa <gustavo.sousa@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231115182117.2551522-2-matthew.d.roper@intel.com

On MTL, the HuC is only supported on the media GT, so our validation
check on the module parameter detects an inconsistency on the root GT
(the modparams asks to enable HuC, but the support is not there) and
prints the following info message:

[drm] GT0: Incompatible option enable_guc=3 - HuC is not supported!

This can be confusing to the user and make them think that something is
wrong when it isn't, so we need to silence it.
Given that any platform that supports HuC also supports GuC, if a user
tries to enable HuC on a platform that really doesn't support it they'll
already see a message about GuC not being supported, so instead of just
silencing the HuC message on newer platforms we can just get rid of it
entirely.
Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: John Harrison <john.c.harrison@intel.com>
Reviewed-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231109235436.2349963-1-daniele.ceraolospurio@intel.com

The only task of intel_gt_release_all is to zero gt table. Calling
it on error path prevents intel_gt_driver_late_release_all (called from
i915_driver_late_release) to cleanup GTs, causing leakage.
After i915_driver_late_release GT array is not used anymore so
it does not need cleaning at all.

Sample leak report:

BUG i915_request (...): Objects remaining in i915_request on __kmem_cache_shutdown()
...
Object 0xffff888113420040 @offset=64
Allocated in __i915_request_create+0x75/0x610 [i915] age=18339 cpu=1 pid=1454
 kmem_cache_alloc+0x25b/0x270
 __i915_request_create+0x75/0x610 [i915]
 i915_request_create+0x109/0x290 [i915]
 __engines_record_defaults+0xca/0x440 [i915]
 intel_gt_init+0x275/0x430 [i915]
 i915_gem_init+0x135/0x2c0 [i915]
 i915_driver_probe+0x8d1/0xdc0 [i915]

v2: removed whole intel_gt_release_all

Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/8489
Fixes: bec68cc9 ("drm/i915: Prepare for multiple GTs")
Signed-off-by: Andrzej Hajda <andrzej.hajda@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231115-dont_clean_gt_on_error_path-v2-1-54250125470a@intel.com

Trace requires new-line at the end of message (in opposition to printk),
otherwise trace dump becomes messy.
Signed-off-by: Andrzej Hajda <andrzej.hajda@intel.com>
Acked-by: Janusz Krzysztofik <janusz.krzysztofik@linux.intel.com>
Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231115-eols-v1-1-d47a2f52b807@intel.com

We read RENDER_HEAD as a part of the flush. If GT is in
deeper sleep states, this could lead to read errors since we are
not using a forcewake. Safer to read a shadowed register instead.

Cc: John Harrison <john.c.harrison@intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Signed-off-by: Vinay Belgaumkar <vinay.belgaumkar@intel.com>
Reviewed-by: Radhakrishna Sripada <radhakrishna.sripada@intel.com>
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231109192148.475156-1-vinay.belgaumkar@intel.com

Use the newly added drm_print_memory_stats helper to show memory
utilisation of our objects in drm/driver specific fdinfo output.

To collect the stats we walk the per memory regions object lists
and accumulate object size into the respective drm_memory_stats
categories.

v2:
 * Only account against the active region.
 * Use DMA_RESV_USAGE_BOOKKEEP when testing for active. (Tejas)

v3:
 * Update commit text. (Aravind)
 * Update to use memory regions uabi names.
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Aravind Iddamsetty <aravind.iddamsetty@intel.com>
Cc: Rob Clark <robdclark@gmail.com>
Cc: Andi Shyti <andi.shyti@linux.intel.com>
Cc: Tejas Upadhyay <tejas.upadhyay@intel.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Reviewed-by: Aravind Iddamsetty <aravind.iddamsetty@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231107101806.608990-6-tvrtko.ursulin@linux.intel.com

At the moment memory region names are a bit too varied and too
inconsistent to be used for ABI purposes, like for upcoming fdinfo
memory stats.

System memory can be either system or system-ttm. Local memory has the
instance number appended, others do not. Not only incosistent but thi
kind of implementation detail is uninteresting for intended users of
fdinfo memory stats.

Add a stable name always formed as $type$instance. Could have chosen a
different stable scheme, but I think any consistent and stable scheme
should do just fine.
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Aravind Iddamsetty <aravind.iddamsetty@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231107101806.608990-5-tvrtko.ursulin@linux.intel.com

Account ring buffers and logical context space against the owning client
memory usage stats.
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Aravind Iddamsetty <aravind.iddamsetty@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231107101806.608990-4-tvrtko.ursulin@linux.intel.com

Account page table backing store against the owning client memory usage
stats.
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Aravind Iddamsetty <aravind.iddamsetty@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231107101806.608990-3-tvrtko.ursulin@linux.intel.com

To enable accounting of indirect client memory usage (such as page tables)
in the following patch, lets start recording the creator of each PPGTT.
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Aravind Iddamsetty <aravind.iddamsetty@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231107101806.608990-2-tvrtko.ursulin@linux.intel.com

In order to show per client memory usage lets add some infrastructure
which enables tracking buffer objects owned by clients.

We add a per client list protected by a new per client lock and to support
delayed destruction (post client exit) we make tracked objects hold
references to the owning client.

Also, object memory region teardown is moved to the existing RCU free
callback to allow safe dereference from the fdinfo RCU read section.
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Aravind Iddamsetty <aravind.iddamsetty@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231107101806.608990-1-tvrtko.ursulin@linux.intel.com

GCC 14 introduces a new -Walloc-size included in -Wextra which errors out
like:
```
drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c: In function ‘eb_copy_relocations’:
drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c:1681:24: error: allocation of insufficient size ‘1’ for type ‘struct drm_i915_gem_relocation_entry’ with size ‘32’ [-Werror=alloc-size]
 1681 |                 relocs = kvmalloc_array(size, 1, GFP_KERNEL);
      |                        ^

```

So, just swap the number of members and size arguments to match the prototype, as
we're initialising 1 element of size `size`. GCC then sees we're not
doing anything wrong.
Signed-off-by: Sam James <sam@gentoo.org>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231107215538.1891359-1-sam@gentoo.org

This workaround applies to all steppings of Xe_LPM+. Implement the KMD
part.

v2:
    - Put the definition of VDBOX_CGCTL3F1C() in the correct sort order.
      (Matt)
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Gustavo Sousa <gustavo.sousa@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231106201959.156943-1-gustavo.sousa@intel.com

FIXME: It is suspected that some Address Translation Service (ATS)
issue on IOMMU is causing CAT errors to occur on some MTL workloads.
Applying a write barrier to the ppgtt set entry functions appeared
to have no effect, so we must temporarily use I915_MAP_WC in the
map_pt_dma class of functions on MTL until a proper ATS solution is
found.
Signed-off-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
CC: Chris Wilson <chris.p.wilson@linux.intel.com>
Reviewed-by: Radhakrishna Sripada <radhakrishna.sripada@intel.com>
Acked-by: Andi Shyti <andi.shyti@linux.intel.com>
Signed-off-by: Andi Shyti <andi.shyti@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231102175831.872763-1-jonathan.cavitt@intel.com

Fix smatch warning:
drivers/gpu/drm/i915/gem/i915_gem_context.c:847 set_proto_ctx_sseu()
warn: potential spectre issue 'pc->user_engines' [r] (local cap)

Fixes: d4433c76 ("drm/i915/gem: Use the proto-context to handle create parameters (v5)")
Cc: <stable@vger.kernel.org> # v5.15+
Signed-off-by: Kunwu Chan <chentao@kylinos.cn>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231103110922.430122-1-tvrtko.ursulin@linux.intel.com

Removes space after opening parenthesis.

Fixes the checkpatch.pl error:
ERROR: space prohibited after that opening parenthesis '('
Signed-off-by: Dorcas AnonoLitunya <anonolitunya@gmail.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Signed-off-by: Andi Shyti <andi.shyti@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231027174745.4058-1-anonolitunya@gmail.com

Hide gpu error specifics in i915_gpu_error.c. This is also cleaner wrt
conditional compilation, as i915_gpu_error.c is only built with
DRM_I915_CAPTURE_ERROR=y.

With this, we can also make i915_first_error_state() static.
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231031124502.1772160-3-jani.nikula@intel.com

Hide gpu error specifics in i915_gpu_error.c. This is also cleaner wrt
conditional compilation, as i915_gpu_error.c is only built with
DRM_I915_CAPTURE_ERROR=y.
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231031124502.1772160-2-jani.nikula@intel.com

Not needed outside of i915_gpu_error.c.
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231031124502.1772160-1-jani.nikula@intel.com

This workaround is primarily implemented by the BIOS.  However if the
BIOS applies the workaround it will reserve a small piece of our DSM
(which should be at the top, right below the WOPCM); we just need to
keep that region reserved so that nothing else attempts to re-use it.

v2: Declare regs in intel_gt_regs.h (Matt Roper)

v3: Shift WA implementation before calculation of *base (Matt Roper)

v4:
-  Change condition gscpmi base to be fall in DSM range.(Matt Roper)
Signed-off-by: Dnyaneshwar Bhadane <dnyaneshwar.bhadane@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231027195052.3676632-1-dnyaneshwar.bhadane@intel.com

Set copy engine arbitration into round robin mode
for part of Wa_16018031267 / Wa_16018063123 mitigation.
Signed-off-by: Nirmoy Das <nirmoy.das@intel.com>
Signed-off-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
Signed-off-by: Andrzej Hajda <andrzej.hajda@intel.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231026-wabb-v6-4-4aa7d55d0a8a@intel.com

Test re-uses logic form indirect ctx BB selftest.
Signed-off-by: Nirmoy Das <nirmoy.das@intel.com>
Signed-off-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
Signed-off-by: Andrzej Hajda <andrzej.hajda@intel.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231026-wabb-v6-3-4aa7d55d0a8a@intel.com

Apply WABB blit for Wa_16018031267 / Wa_16018063123.

v3: drop unused enum definition
v4: move selftest to separate patch, use wa only on BCS0.
v5: fixed selftest caller to context_wabb
Signed-off-by: Nirmoy Das <nirmoy.das@intel.com>
Signed-off-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
Signed-off-by: Andrzej Hajda <andrzej.hajda@intel.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231026-wabb-v6-2-4aa7d55d0a8a@intel.com

Reserve one page in each vm for kernel space to use for things
such as workarounds.

v2: use real memory, do not decrease vm.total
v4: reserve only one page and explain flag
v5: remove allocated object on ppgtt cleanup
v6: decrease vm->total by reservation size
Suggested-by: Chris Wilson <chris.p.wilson@linux.intel.com>
Signed-off-by: Andrzej Hajda <andrzej.hajda@intel.com>
Reviewed-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231026-wabb-v6-1-4aa7d55d0a8a@intel.com

Implemented workaround for XeLPM+
BSpec: 51762
Signed-off-by: Dnyaneshwar Bhadane <dnyaneshwar.bhadane@intel.com>
Reviewed-by: Balasubramani Vivekanandan <balasubramani.vivekanandan@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231025131709.3368517-1-dnyaneshwar.bhadane@intel.com

Do the logical step of first getting from struct hrtimer to struct
i915_pmu, and then from struct i915_pmu to struct drm_i915_private,
instead of hrtimer->i915->pmu.
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231023150256.438331-3-jani.nikula@intel.com

It's tedious to duplicate the container_of() everywhere. Add a helper.

Also do the logical steps of first getting from struct perf_event to
struct i915_pmu, and then from struct i915_pmu to struct
drm_i915_private if needed, instead of perf_event->i915->pmu. Not all
places even need the i915 pointer.
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Acked-by: Andi Shyti <andi.shyti@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231023150256.438331-2-jani.nikula@intel.com

It's tedious to duplicate the container_of() everywhere. Add a helper.
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231023150256.438331-1-jani.nikula@intel.com

When i915 perf interface is not available dereferencing it will lead to
NULL dereferences.

As returning -ENOTSUPP is pretty clear return when perf interface is not
available.

Fixes: 2fec5391 ("i915/perf: Replace DRM_DEBUG with driver specific drm_dbg call")
Suggested-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: <stable@vger.kernel.org> # v6.0+
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231027172822.2753059-1-harshit.m.mogalapalli@oracle.com
[tursulin: added stable tag]

Fix checkpatch.pl error:

WARNING: braces {} are not necessary for any arm of this statement
Signed-off-by: Gilbert Adikankwu <gilbertadikankwu@gmail.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Signed-off-by: Andi Shyti <andi.shyti@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231026105623.480172-1-gilbertadikankwu@gmail.com