[Intel-gfx] [PATCH 020/190] drm/i915: Remove the lazy_coherency parameter from request-completed?

[Chris Wilson]

On Tue, Jan 12, 2016 at 12:27:05PM +0200, Mika Kuoppala wrote:
> >  	for_each_ring(ring, dev_priv, i) {
> > -		seqno[i] = ring->get_seqno(ring);
> >  		acthd[i] = intel_ring_get_active_head(ring);
> > +		seqno[i] = ring->get_seqno(ring);
> 
> Oh! Perhaps I am overly optimistic but did you just show how to solve
> the 'hangcheck elapsed <random> ring idle..' coherency issue
> in hangcheck?

No. There are two causes, one is that we genuinely inspect the seqno
before it is written in the interrupt bottom-half and the other is
indeed the race you keep mentioning between the hangcheck looking at
waiters and the waiter setting itself up.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre