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

[Mika Kuoppala]

Chris Wilson <chris at chris-wilson.co.uk> writes:

> 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.
>

Agreed that we should do a blanket approach. I was in a hurry
to post a proposed fix as I heard the prime_* are not yet
blacklisted on shards. So lets hope this helps.

> Other than,
> Acked-by: Chris Wilson <chris at chris-wilson.co.uk>
> for the find.

Ta.

-Mika