https://bugs.freedesktop.org/show_bug.cgi?id=76490
--- Comment #6 from Alex Deucher agd5f@yahoo.com --- Have you installed the latest mc ucode for pitcarin? http://people.freedesktop.org/~agd5f/radeon_ucode/PITCAIRN_mc2.bin make sure that is installed and available in your initrd if you are using one.