When doing bring-ups on embedded devices a useful way to test if a display interface is working is this command: Apalis iMX6 $ dd if=/dev/urandom of=/dev/fb0 This shows random data on the display and a lot of gray, red, blue, and green dots appear. This doesn't tell us if everything is working as expected because maybe the resolution is wrong or some timings are too tight but it gives already an indication if the display controller works and if the display gets some understandable data. However,...