Do you have this file in your system? /lib/firmware/radeon/RV770_smc.bin
From this: http://lxr.free-electrons.com/source...70_dpm.c#L1415 (man, this website is really useful) , I guess it either doesn't exist, or it fails to do something with it...
I'm not a dev, so wait for them to reply, or ask them in IRC: freenode / #radeon
BTW, the file is in the package linux-firmware (in Ubuntu, I dunno how it is called in other distros.)