https://bugs.freedesktop.org/show_bug.cgi?id=89987
--- Comment #4 from Christian König deathsimple@vodafone.de --- (In reply to James Le Cuirot from comment #0)
This has similarities to bug #69120 but I believe that to be a different issue because it involves much older kernel versions and a lot has changed since then, plus it used to work for me until 3.18.
Yeah, that is indeed a completely different issue, so opening up a new bug report was the right thing to do.
[drm:rv770_dpm_set_power_state [radeon]] *ERROR* rv770_restrict_performance_levels_before_switch failed
This led me to try booting with radeon.dpm=0. Under the high profile, low quality is smooth and high quality improves to just jumpy. Under the dynpm method, both are smooth.
I have two displays connected using Zaphod mode, both normally at 1080p. If I disconnect the second, playback is smooth. If I set the second to some low resolution like 720x480 but play 1080p video on the first, playback is smooth. I'm not sure whether this behaviour is a symptom or a cause.
Thanks for the detailed report, but unfortunately I can't help much and Alex need to take a look at this.
The issue is that the driver send a message to the SMU to raise the clocks for playback and with two connected monitors that fails for some reason.