https://bugs.freedesktop.org/show_bug.cgi?id=97861
--- Comment #2 from Ivan Bulatovic combuster@archlinux.us --- Same problem here, 4.9-rc1, AMD R270X, Xorg 1.18.4, xf86-video-amdgpu from git master, purple line and the screen is very blurry.
xrandr --output HDMI-A-0 --auto --set audio off
helps, thanks.