Make sure that all outputs are disabled before unloading the DRM driver. Otherwise vblank handling is not shut down properly and warnings such as this appear: WARNING: CPU: 0 PID: 540 at drivers/gpu/drm/drm_irq.c:339 drm_vblank_cleanup+0x5c/0x94 Signed-off-by: Stefan Agner <stefan@agner.ch>