[Intel-gfx] [CI 3/5] drm/i915: Disable semaphores on Sandybridge

[Chris Wilson]

Quoting Jani Nikula (2017-11-21 09:57:30)
> On Mon, 20 Nov 2017, Chris Wilson <chris at chris-wilson.co.uk> wrote:
> > I should have admitted defeat long ago as there has been a rare but
> > persistent error on Sandybridge where semaphore signaling did not
> > propagate to the waiter, leading to a GPU hang.
> 
> I'm late to the party, but I think the choice of patch ordering here is
> a bit unfortunate. Or is it intentional that you can't backport this to
> stable as-is?

The unmentioned problem with this patch, is that we were using
semaphores to mask the missed-breadcrumb-syndrome on Sandybridge (and
that without semaphores we are even more at risk). So I am not too
concerned in backporting this particular patch further than we are able
to inspect ourselves.
-Chris