https://bugs.freedesktop.org/show_bug.cgi?id=30313
--- Comment #5 from Marek Olšák maraeo@gmail.com 2010-09-24 18:34:35 PDT --- This looks like a tiling issue and r300c doesn't implement tiling fully. I can't reproduce it on R500. Try to set the environment variable RADEON_DEBUG=notiling and please let me know if it fixes the issue.