[Intel-gfx] [PATCH v4 2/2] drm/i915/perf: fix ctx_id read with GuC & ICL

[Michel Thierry]

On 06/02/2018 07:43 AM, Lionel Landwerlin wrote:
> On 02/06/18 12:52, Chris Wilson wrote:
>> Quoting Lionel Landwerlin (2018-06-02 12:29:46)
>>> One thing we didn't really understand about the OA report is that the
>>> ContextID field (dword 2) is copy of the context descriptor (dword 1).
>>>
>>> On Gen8->10 and without using GuC we didn't notice the issue because
>>> we only checked the 21bits of the ContextID field in the OA reports
>>> which matches exactly the hw_id stored into the context descriptor.
>>>
>>> When using GuC submission we have an issue of a non matching hw_id
>>> because GuC uses bit 20 of the hw_id to signal proxy submission. This
>>> change introduces a mask to compare only the relevant bits.
>>>
>>> On ICL the context descriptor format has changed and we failed to
>>> address this. On top of using a mask we also need to shift the bits
>>> properly.
>>>
>>> v2: Reuse lrc_desc rather than recomputing part of it (Chris/Michel)
>>>
>>> v3: Always pin the context we're filtering with (Chris)
>>>
>>> Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
>>> Fixes: 1de401c08fa805 ("drm/i915/perf: enable perf support on ICL")
>>> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=104252
>>> BSpec: 1237
>>> Testcase: igt/perf/gen8-unprivileged-single-ctx-counters
>> Acked-by: Chris Wilson <chris at chris-wilson.co.uk>
>>
>> Please ping Michel for an r-b confirmation on using the lrca for the guc
>> ctx_id.
>> -Chris
>>
> Got the information from Michel initially ;)
> Will wait for his Rb on the last version.

Both patches,

Reviewed-by: Michel Thierry <michel.thierry at intel.com>