Comment # 41 on bug 1193250 from Paolo Stivanin

After yesterday's update, I have the same issue again (unknown non-existent
monitor):

$ find /sys/devices -name "edid"
/sys/devices/pci0000:64/0000:64:00.0/0000:65:00.0/drm/card1/card1-DP-4/edid
/sys/devices/pci0000:64/0000:64:00.0/0000:65:00.0/drm/card1/card1-DP-2/edid
/sys/devices/pci0000:64/0000:64:00.0/0000:65:00.0/drm/card1/card1-DP-3/edid
/sys/devices/pci0000:64/0000:64:00.0/0000:65:00.0/drm/card1/card1-DP-1/edid
/sys/devices/platform/simple-framebuffer.0/drm/card0/card0-Unknown-1/edid


adding the usual nosimplefb and reboot did the trick.