Steps to reproduce:
1) echo low > /sys/class/drm/card0/device/power_dpm_force_performance_level
2) cat /sys/class/drm/card0/device/power_dpm_force_performance_level
   low
3) start playing a video (vdpau)
4) cat /sys/class/drm/card0/device/power_dpm_force_performance_level
   auto

Interestingly, I can repeat step 1 now and the video will play correctly, with
the value staying at "low". So it seems this occurs only when initializing
video playback (vdpau).

This started happening with kernel 3.12.0 or a rc. It did not get reset with
<=3.11.8.