https://bugs.freedesktop.org/show_bug.cgi?id=88493
--- Comment #17 from Timo Aaltonen tjaalton@ubuntu.com --- Not sure if I'm seeing the same, but I have the HDMI/DP audio device available with 4.0-rcN, just get no sound through it. This worked with 3.19. Another datapoint is that pulling most of core drm changes from 4.0-rc1 (for SKL backport) also broke it, so that the HDMI audio device isn't even available.