On Sat, 29 Apr 2017, Robert Elz wrote:
I can try turning on more debug in there (there appears to be lots) but I'm not sure I can ever figure out what any of it means, or which debug in particular might be relevant.
It looks like if you can set the global int drm_debug to 2 you should getdriver debug messages from i915drm (including some about DP/HDMI audio setup).