[Intel-gfx] [PATCH 5/7] drm/i915: Take forcewake for setting the RPS thresholds

[Chris Wilson]

On Mon, Feb 20, 2017 at 04:34:43PM +0200, Mika Kuoppala wrote:
> Chris Wilson <chris at chris-wilson.co.uk> writes:
> 
> > Take forcewake for the entire duration of reprogramming the RPS
> > thresholds. By itself it should not achieve much as instead of going
> > into the FIFO, we force the device to wake for the reprograming, but it
> > should help in regards to the next patch that introduces a read.
> >
> > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> 
> The recommendation is to keep it during init. And this is
> part of our init and reinit to different values, this makes
> a lot of sense. This kind of approach was tried to byt
> hangs and had a significant change to the repeability.
> 
> But that test didnt have rps off during reinit and the
> forcewake was not as exclusive as this version.

Yup, I think it is the combination of RP_CONTROL=0, rc6 off and avoid
IDLE_AVG that is the secret. Either by themselves didn't survive very long
on my j1900, but together it's at 77 hours, hoping to hit the 4 week mark ;)
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre