https://bugs.freedesktop.org/show_bug.cgi?id=72051
--- Comment #9 from Alex Deucher agd5f@yahoo.com --- (In reply to comment #8)
first bad commit: [d1e3b5564834ea24dee6b364a172365f64865fe5] drm/radeon: atombios hw i2c fixes
You must have radeon.hw_i2c=1 set somewhere then. Anyway, this is fixed in: http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=ff...