Comment 2 for bug 1477587

Since the regression started in 3.19.0-22.22 (https://launchpad.net/ubuntu/+source/linux/3.19.0-22.22), it looks like its a stable update regression. I noticed in the upstream stable 3.18.18 release a few radeon commits were reverted that we haven't reverted yet

      Revert "drm/radeon: don't share plls if monitors differ in audio support"
      Revert "drm/radeon: adjust pll when audio is not enabled"

https://lkml.org/lkml/2015/7/11/94