confirmed that the following sequence displays a non-garbled 1920x1080 display on the external monitor:
# xrandr --newmode "1920x1080R" 138.50 1920 1968 2000 2080 1080 1083 1088 1111 +hsync -vsync # xrandr --addmode HDMI-0 1920x1080R # xrandr 1920x1080R
confirmed that the following sequence displays a non-garbled 1920x1080 display on the external monitor:
# xrandr --newmode "1920x1080R" 138.50 1920 1968 2000 2080 1080 1083 1088 1111 +hsync -vsync
# xrandr --addmode HDMI-0 1920x1080R
# xrandr 1920x1080R