[Intel-gfx] [PATCH 2/2] drm/i915/gt: Warn if not in RC6 when GT is parked

[Tvrtko Ursulin]

On 11/10/2022 06:53, Dixit, Ashutosh wrote:
> On Mon, 10 Oct 2022 20:29:23 -0700, Ashutosh Dixit wrote:
>>
>> Some i915 modules implicitly assume that there is no user, kernel or
>> firmware activity after GT is parked. For example, PMU calculations are
>> incorrect if GT is not in RC6 when GT is parked (outside of the GT
>> wakeref). Therefore check and warn if GT is not in RC6 at the time of
>> parking the GT.
> 
> This patch has cause widespread dmesg_warn's in premerge CI so there is no
> intention of merging this. It just proves that these assumptions in PMU
> (for quantities such as frequency and RC6 residency) are incorrect and need
> to be addressed.

Yeah this probably does not make sense since I am not sure if driver 
actually controls when hardware goes into RC6.

Regards,

Tvrtko

> 
> Thanks.
> --
> Ashutosh
> 
> 
>> @@ -123,6 +125,10 @@ static int __gt_park(struct intel_wakeref *wf)
>> 		intel_display_power_put_async(i915, POWER_DOMAIN_GT_IRQ, wakeref);
>> 	}
>>
>> +	ret = intel_rc6_in_rc6(&gt->rc6, &in_rc6);
>> +	if (!ret && !in_rc6)
>> +		drm_warn_once(&i915->drm, "Parking, but GT is not in RC6!\n");
>> +
>> 	return 0;
>>   }