I’ve followed the various blogs and videos, and have built a custom OE layer for my carrier board, including various kernel patches and device tree changes. My board uses PWM2 (pin 4 GPIO01) as the backlight enable signal instead of the standard pin (286), which I’ve successfully addressed in patching the device tree. I’ve also applied a patch for my kernel splash screen, which also works nicely
I’ve disabled all console output in u-boot which also works, so the first content displayed on the display is the kernel splash screen. However, the display back light toggles on/off briefly during u-boot before turning on during kernel initialisation. I’d like to be able to keep the back light completely disabled until the kernel splash image is ready. I also notice that when the back light does turn on for the kernel, there appears to be, for a fraction of a second, the remnants of a cursor in the top right of the display as the splash screen is initially displayed. As mentioned above, I’ve disabled console output as well as cursor output (
vt.global_cursor_default=0) for u-boot, so I’m not sure what this artefact could be.
- Which is the recommended approach for setting the back light enable signal low until it’s under the kernel’s control? I’ve tried the setenv approach listed here without success. Would patching the apalis_imx6.c file, changing the definition of
RGB_BACKLIGHT_GP, 0be suitable?
- Can you think of any reason why I’d have a momentary artefact when the kernel splash screen initialises? Are there any additional console/framebuffer parameters I need to disable to ensure when the display does first turn on, the kernel splash screen is displayed cleanly?