Re: [Intel-gfx] [PATCH v2 1/2] drm/i915/guc: Properly initialise kernel contexts

John Harrison
2022-11-04T18:58:39Z

On 11/4/2022 11:53, Ceraolo Spurio, Daniele wrote:
> On 11/2/2022 12:21 PM, John.C.Harrison@Intel.com wrote:
>> From: John Harrison <John.C.Harrison@Intel.com>
>>
>> If a context has already been registered prior to first submission
>> then context init code was not being called. The noticeable effect of
>> that was the scheduling priority was left at zero (meaning super high
>> priority) instead of being set to normal. This would occur with
>> kernel contexts at start of day as they are manually pinned up front
>> rather than on first submission. So add a call to initialise those
>> when they are pinned.
>
> Does this need a fixes tag? on one side, we were leaving the priority
> to the wrong value, but on the other there were no actual consequences.
>
I think that's the point. There was no actual issue, it's just a
theoretical problem. So there is nothing to be gained by pushing this as
a fix. It it seems like it would be a lot of unnecessary effort to push
it all the way back to 5.17.

John.

> Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
>
> Daniele
>
>> Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
>> ---
>>   drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c | 3 +++
>>   1 file changed, 3 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
>> b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
>> index 4ccb29f9ac55c..941613be3b9dd 100644
>> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
>> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
>> @@ -4111,6 +4111,9 @@ static inline void
>> guc_kernel_context_pin(struct intel_guc *guc,
>>       if (context_guc_id_invalid(ce))
>>           pin_guc_id(guc, ce);
>>   +    if (!test_bit(CONTEXT_GUC_INIT, &ce->flags))
>> +        guc_context_init(ce);
>> +
>>       try_context_registration(ce, true);
>>   }
>