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

[Dixit, Ashutosh]

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.

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;
>  }