https://bugs.freedesktop.org/show_bug.cgi?id=85320
--- Comment #3 from Eugene ken20001@ukr.net --- (In reply to Alex Deucher from comment #1)
If this is a regression can you narrow down which component (kernel, mesa, etc.) caused the problem and bisect? Please also attach your xorg log and dmesg output.
And yes, I would do bisect if somebody explain how to. But I don't know.