[ubuntu-x] i915 powersave/fbc issues on i945 and older

[Robert Hooker]

> Also there are rumours that disabling framebuffer compression only might
> also help the issue.  Here is a patch stolen from Sarvatt which just
> turns that off which is also worth testing if you experience these
> issues:
>
>    http://people.canonical.com/~apw/i915-fbc-broken-lucid/


Indeed it did turn out to be FBC related, this kernel has worked for
me for 36 hours now post resume. I noticed it was FBC related because
intel_gpu_top showed it 100% busy in framebuffer compression when it
would hang. I have sent my patch along upstream to the intel-gfx list
after speaking to jbarnes in #intel-gfx.

<jbarnes> [14:10:21] +Sarvatt: cool, can you post it?
<jbarnes> [14:10:26] +it should be disabled on 915/945

http://lists.freedesktop.org/archives/intel-gfx/2010-March/006292.html

I am using bug #492393 for dupes for future reference since it's very
distinguishable, the symptoms are hanging with a solid color screen
after resume, no GPU hang in dmesg when it happens, 915-945 mobile
chipsets, powersave=0 fixes it, and another suspend/resume cycle
clears it for a few hours more until it eventually hangs.  With 2.6.32
drm it would flicker post resume until it eventually hung, but only
the hangs are still there with the .33 drm on 2.6.32-16+

Thanks,
Robert