[PATCH] drm/i915/gt: Add a delay to let engine resumes correctly

[Gote, Nitin R]

Hi Krzysztof,

> Hi Nitin,
> 
> [...]
> > Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/13650
> [...]
> 
> >  			     ENGINE_READ_FW(engine, RING_START));
> > +		/*
> > +		 * Sometimes engine head failed to set to zero even after writing
> into it.
> > +		 * Use 20ms delay to let engine resumes from correct
> RING_HEAD.
> > +		 * Experimented different values and determined that 20ms
> works best
> > +		 * based on testing.
> > +		 */
> > +		mdelay(20);
> Since we do not propagate the errors returned from `stop_ring()` function and the
> linked issue is not a failure, because the subtest succeeds, I wonder if we could
> lower the severity of this log to a warning.
> 
> Regardless of whether you consider my suggestion or not, the patch looks good to
> me:
> 

Thank you for the review.
I'm not sure about severity of this log and I think it's intentionally kept as error for some corner case.
But, your point is also seems valid. I would like to handle this in separate patch.

- Nitin

> Reviewed-by: Krzysztof Karas <krzysztof.karas at intel.com>
> 
> Best Regards,
> Krzysztof