[Intel-gfx] [PATCH] drm/i915: Stop ring before doing readiness check

[Ville Syrjälä]

On Wed, Sep 13, 2017 at 03:08:06PM +0100, Chris Wilson wrote:
> Quoting Mika Kuoppala (2017-09-13 15:01:17)
> > Evidence indicates that even if the hardware happily
> > tells us to proceed with reset, it really isn't ready.
> > Resetting a freely running batchbuffer after we have
> > got ack for readiness, still can cause a system hang.
> 
> Hmm, so we see it on early gen and late gen. I suggest we do it
> universally (except gen2 which is lacking the mechanism). It's unlikely
> that the requirement disappeared just for a couple of gen, more likely
> that we simply haven't triggered the pathological behaviour.

Could just try setting ring enable=false on gen2 maybe? But we don't have
GPU reset for gen2 anyway so I guess it doesn't matter.

-- 
Ville Syrjälä
Intel OTC