https://bugs.freedesktop.org/show_bug.cgi?id=97861
--- Comment #10 from James Wagner james.a.wagner3@gmail.com --- 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.