[Intel-gfx] [PATCH 1/2] drm/i915: tune the RC6 threshold for stability

[Chris Wilson]

On Tue, Jun 11, 2013 at 03:49:26PM -0700, Stéphane Marchesin wrote:
> It's basically the same deal as the RC6+ issues on ivy bridge
> except this time with RC6 on sandy bridge. Like last time the
> core of the issue is that the timings don't work 100% with our
> voltage regulator. So from time to time, the kernel will print
> a warning message about the GPU not getting out of RC6. In
> particular, I found this fairly easy to reproduce during
> suspend/resume.
> 
> Changing the threshold to 150000 instead of 50000 seems to fix
> the issue.
> 
> I also measured the idle power usage before/after this patch and
> didn't see a difference on a sandy bridge laptop.
> 
> Signed-off-by: Stéphane Marchesin <marcheu at chromium.org>

One magic number for another with no idea what is blowing up - I fear we
are just changing the frequency of the hang. I've pinged a number of snb
rc6 bug reports to see if we get a bite.

FWIW,
Acked-by: Chris Wilson <chris at chris-wilson.co.uk>
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre