https://bugzilla.kernel.org/show_bug.cgi?id=79051
--- Comment #2 from Ed Tomlinson edt@aei.ca --- I am seeing a similar panic on a R7 260X.
See: https://plus.google.com/u/0/photos/108244876431105742323/albums/602963126038...
I cannot reproduce this on demand. I am currently trying patch #2 and will report if I see impossible msc times.