https://bugzilla.kernel.org/show_bug.cgi?id=65761
--- Comment #32 from Hohahiu rakothedin@gmail.com --- I have the same messages in dmesg: http://pastebin.com/vAsRRVW8
It seems like radeon driver tries to set clock and it couldn't do it. Therefore it tries again and again and GPU does not turn off.
Christoph, does your dmesg have the same messages?