I have a new custom board, and i want to do things like test gpio connections, test my display etc. my display, for example, is being held in a disabled state (i.e., the backlight and logic power supplies) so i can't even see if the backlight works.
i'm having trouble compiling and flashing u-boot, so i was wondering: using the i.mx6ull evk sd card demo, can i use the u-boot command line to toggle gpios and do other things like set a test image on the lcd if it comes up? i see that i can read and write registers directly, and i also see there is a gpio command, but i can't get any of it to work because i don't know the proper syntax to go with the demo sd u-boot build.
how can i test my board with the demo sd u-boot, without having to modify and re-compile underlying c-code?