https://bugzilla.kernel.org/show_bug.cgi?id=60741
--- Comment #6 from Alex Deucher alexdeucher@gmail.com --- (In reply to Eastern Heart from comment #5)
I cannot try now... And I cannot even boot, not incorrect display! I said, my boot paused when start the kernel radeon module. Sorry.
The patch is still be relevant, you may just have different symptoms on your system. Without the patch garbage gets written to certain registers which may cause the card to hang or cause display problems, or nothing at all depending on what registers are written to.