Re: [PATCH] drm/i915: Abandon the reset if we fail to stop the engines

Ville Syrjälä
2017-10-26T13:30:32Z

On Thu, Oct 26, 2017 at 02:11:22PM +0100, Chris Wilson wrote:
> Quoting Ville Syrjälä (2017-10-26 13:59:05)
> > On Thu, Oct 26, 2017 at 01:12:12PM +0100, Chris Wilson wrote:
> > > Some machines, *cough* snb *cough*, fail catastrophically if asked to
> > > reset the GPU under certain conditions.
> >
> > Did we try skipping the gen6_rps_disable() already?
>
> I had thought we had taken that out a while ago...
>
> commit f2a91d1a6f5960c08f1ca60bd076f4dc020c50c6
> Author: Chris Wilson <chris@chris-wilson.co.uk>
> Date: Wed Sep 21 14:51:06 2016 +0100
>
> drm/i915: Restore current RPS state after reset
>
> removes the frobbing inside i915_reset() itself, but still talks about
> RPS needing to be restored... Ok, that's the post-reset stuff to make
> sure that the hw/sw tracking align.

Hmm. Right. It looks like we do the disable+re-enable back to back after
the reset. I guess at that point it should be safe, assuming the reset
actually worked.

>
> We are not touching rc6/rps prior to hitting GDRST. Maybe we should?

Based on what I remember that would be more dangerous if the engined is
stuck in a bad way.

So I guess these reset problems are something else then.

--
Ville Syrjälä
Intel OTC