[Intel-gfx] [PATCH] drm/i915: Handle sync_seqno correctly when seqno has wrapped.

[Daniel Vetter]

On Tue, Nov 13, 2012 at 5:39 PM, Ben Widawsky <ben at bwidawsk.net> wrote:
>
> Also as an overall comment, I want the patches to guarantee to catch
> the bug you found, which I think with the randomness of
> gem_stress - isn't. Specifically, we want the waiting ring to be
> waiting on a pre-wrapped value. Maybe I missed that guarantee, but if
> there is a quick/dirty way to make that happen, that would better than
> running an arbitrary number of gem_stress tests.

I think running just gem_stress is ok - as long as the test has a
reasonable good chance of blowing up. On future platforms something
else than semaphores might blow up, or we might simply botch a seqno
comparison. So imo having a test that just beats a bit on the
systems+the wrap-around after each boot/resume should give us
excellent coverage, and trying to engineer a perfect test for the
single failure mode we now have in front of us might actually reduce
coverage.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch