https://bugs.freedesktop.org/show_bug.cgi?id=47765
--- Comment #10 from Andy Furniss lists@andyfurniss.entadsl.com 2012-04-04 15:14:53 PDT --- (In reply to comment #9)
Created attachment 59494 [details] [review] Fix pixmap.height < 64 case
This should fix your issue (patch against ddx xf86-video-ati)
Doesn't help on my rv790 - I am testing just this patch not the kernel one.
FWIW I only see this when swapbufferswait is off, looks like most/any mesa demo will show it.