https://bugs.freedesktop.org/show_bug.cgi?id=68805
--- Comment #2 from kwahoo2@wp.pl --- I have very similar config to your (3.11 + DPM + oibaf PPA) except HD 6670 instead 6310 - but vdpainfo output looks exactly the same. However, I cannot confirm your issue. I am curious what is your /sys/kernel/debug/dri/0/radeon_pm_info?
Mine: sudo cat /sys/kernel/debug/dri/0/radeon_pm_info uvd vclk: 70000 dclk: 56000 power level 0 sclk: 80000 mclk: 100000 vddc: 1100 vddci: 0