[Intel-gfx] [PATCH 2/9] drm/i915/perf: Add helper to check supported OA engines

[Umesh Nerlige Ramappa]

On Wed, Feb 15, 2023 at 07:58:02PM -0800, Dixit, Ashutosh wrote:
>On Tue, 14 Feb 2023 16:54:12 -0800, Umesh Nerlige Ramappa wrote:
>>
>> Add helper to check for supported OA engines.
>>
>> Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa at intel.com>
>> ---
>>  drivers/gpu/drm/i915/i915_perf.c | 19 ++++++++++++++++---
>>  1 file changed, 16 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/i915_perf.c b/drivers/gpu/drm/i915/i915_perf.c
>> index 393a0da8b7c8..a879ae4bf8d7 100644
>> --- a/drivers/gpu/drm/i915/i915_perf.c
>> +++ b/drivers/gpu/drm/i915/i915_perf.c
>> @@ -1570,6 +1570,19 @@ free_noa_wait(struct i915_perf_stream *stream)
>>	i915_vma_unpin_and_release(&stream->noa_wait, 0);
>>  }
>>
>> +static bool engine_supports_oa(const struct intel_engine_cs *engine)
>> +{
>> +	enum intel_platform platform = INTEL_INFO(engine->i915)->platform;
>> +
>> +	if (intel_engine_is_virtual(engine))
>> +		return false;
>
>Let's move this check to a different (or a separate) patch (with
>explanation about OA and virtual engines in case of separate patch). It is
>strange to see this check in this patch since previously we have only
>supported render (I think there is only a single render engine so no
>virtual render engines are possible, correct?).

will do.

>
>With the changes above this is:
>
>Reviewed-by: Ashutosh Dixit <ashutosh.dixit at intel.com>
>
>Is there anything intrinsically wrong with virtual engines that we cannot
>get OA data for them? Since we get OA data from an OA unit not engines so
>wondering why this restriction. So if I have a virtual engine consisting of
>two VDBOX engines attached to a single OAM unit we cannot get OA data for
>this virtual engine?
>
>Or is just that we haven't handled such cases? In that case it is fine to
>disallow virtual engines till we can support them. Sorry just trying to
>understand the restriction.

iirc, we cannot modify the context image for the virtual engine.  
Something to do with lrc state for such engines. Also OA supports only a 
concept of one engine instance passed to it, so a virtual engine does 
not fit the interface definition.

Thanks,
Umesh