When I fullscreen a video in mplayer2 (gl3 vo driver), my display freezes -
usually for a number of seconds - after which the fullscreen completes
successfully and continues playing.

Sometimes the hang is very brief or even unnoticable (I think if I had recently
played a video fullscreen - which may make troubleshooting harder).

During the hang, CPU appears to be idle, I *think* I/O wait is high (but
nothing showed in iotop), and perf top didn't notice anything busy.

This does not affect my 5850 card, only the 7950.