[Intel-gfx] [PATCH 1/2] drm/i915/perf: use the lrc_desc to get the ctx hw id in gen8-10

[Lionel Landwerlin]

On 05/06/18 00:18, Michel Thierry wrote:
> On 6/4/2018 4:11 PM, Lionel Landwerlin wrote:
>> On 04/06/18 22:40, Michel Thierry wrote:
>>> The upper 32 bits of the lrc_desc (bits 52-32 to be precise) are the
>>> context hw id in GEN8-10, so use them and have one less thing to
>>> maintain in the unlikely case we change the descriptor sw fields.
>>>
>>> Signed-off-by: Michel Thierry <michel.thierry at intel.com>
>>> Cc: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
>>> Cc: Chris Wilson <chris at chris-wilson.co.uk>
>>> ---
>>>   drivers/gpu/drm/i915/i915_perf.c | 3 ++-
>>>   1 file changed, 2 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/gpu/drm/i915/i915_perf.c 
>>> b/drivers/gpu/drm/i915/i915_perf.c
>>> index a6c8d61add0c..36b6d64d6018 100644
>>> --- a/drivers/gpu/drm/i915/i915_perf.c
>>> +++ b/drivers/gpu/drm/i915/i915_perf.c
>>> @@ -1279,7 +1279,8 @@ static int oa_get_render_ctx_id(struct 
>>> i915_perf_stream *stream)
>>>               i915->perf.oa.specific_ctx_id_mask =
>>>                   (1U << (GEN8_CTX_ID_WIDTH - 1)) - 1;
>>>           } else {
>>> -            i915->perf.oa.specific_ctx_id = stream->ctx->hw_id;
>>> +            i915->perf.oa.specific_ctx_id =
>>> +                upper_32_bits(ce->lrc_desc);
>>>               i915->perf.oa.specific_ctx_id_mask =
>>>                   (1U << GEN8_CTX_ID_WIDTH) - 1;
>>>           }
>>
>> I would do this :
>>
>> i915->perf.oa.specific_ctx_id_mask = (1U << GEN8_CTX_ID_WIDTH) - 1;
>> i915->perf.oa.specific_ctx_id = upper_32_bits(ce->lrc_desc) & 
>> i915->perf.oa.specific_ctx_id_mask;
>>
>> Same for Gen11.
>> I'm concerned otherwise we might get incorrect comparison in the 
>> gen8_append_oa_reports on the "reserved" bits.
>>
>
> For some reason I thought specific_ctx_id_mask was already being 
> applied to this ctx_id... but no, you're right, otherwise the 
> oa.specific_ctx_id == ctx_id check in gen8_append_oa_reports may fail.

Yeah, only applied on the OA report side :(

>
>> Thanks,
>>
>> -
>> Lionel
>>
>