https://bugs.freedesktop.org/show_bug.cgi?id=58667
--- Comment #23 from Alex Deucher agd5f@yahoo.com --- (In reply to comment #22)
"Is this a regression? Does it happen with older versions of mesa or kernel?" Yes. Previous kernel 3.7 doesn't show this problem.
Can you bisect? Is it the same commit Thomas landed on or another one?