https://bugs.freedesktop.org/show_bug.cgi?id=56405
--- Comment #36 from Michael Dressel mdrslmr@t-online.de --- (In reply to comment #35)
To confirm, does: Option "ColorTiling2D" "false" in the device section of your xorg.conf also fix the issues?
No it does not solve this bug but it solves bug #56986 for me.