Comment # 10 on bug 97861 from James Wagner

Same purple line on my R9 280X

Debian 9.0 (Testing)
Linux 4.10.6 with amdgpu for SI and CIK enabled (From kernel.org)
X.Org 1.19.2, from Debian.

`xrandr --output HDMI-A-0 --auto --set audio off` is a valid workaround, 
though it means that TV outputs have to be on the second display.

I also saw [drm] xxxx: dce_v6_0_afmt_setmode ----no impl !!!!!!!!
every time HDMI sound was enabled.