Debian on JWS3288 (RK3288) - LCD stays black, everything else works

cesarromero

Hi everyone,

I have a JWS3288 industrial board (Rockchip RK3288). It originally ran Android with the LCD working fine. I installed Debian 10 (image RK3288-Debian10-20231108.095729.img) using RKDevTool.

Everything works: SSH, network, Wi-Fi. But the LCD stays completely black, no backlight visible.

In software everything looks OK:
- /dev/fb0 exists (1024x768) and accepts writes
- DRM binds correctly (VOP + LVDS)
- Backlight sysfs reports bl_power=0, brightness=255
- LCD regulators are enabled

But physically the panel is off. Writing to /dev/fb0 shows nothing, not even a faint image with a flashlight.

My guess: the DTB in this Debian image is generic (probably Firefly-RK3288) and doesn't match the actual panel/backlight GPIO/PWM mapping of the JWS3288.

Has anyone gotten Debian working on a similar industrial RK3288 board? Any tips on how to extract or adapt the DTB from the original Android ROM?

Thanks!

1winbizpk

Have you checked the display connector and the backlight driver? On Rockchip boards running Debian, the LCD backlight is often controlled by a PWM GPIO that needs to be explicitly enabled in the device tree. Try running cat /sys/class/backlight/brightness to see if the backlight node exists — if it does, writing a non-zero value should turn it on.