Yep, I rechecked it and it seems set to 1 always...

Anyway I gathered around 18 Mb of mmiotrace logs to investigate. Now digging
through divider and clock registers.

P.S. I only fear that maybe I launched mmiotrace too late, I did rmmod and then
modprobe fglrx again. Could it setup any registers at the first run? Because at
second it touched UVD only when I launched mpv.