https://bugs.freedesktop.org/show_bug.cgi?id=58042
--- Comment #26 from Alex Deucher agd5f@yahoo.com --- (In reply to comment #25)
Could you test this patch http://lists.freedesktop.org/archives/mesa-dev/2013-February/035347.html
Patch 3/5 doesn't help for me. Should I try out the other patches in that series? (nee ATI RV670 [Radeon HD 3870], Git kernel (pre 3.9))
The only patch that's relevant for r6xx is 2/5. Does that help? You might need to apply 1/5 first.