Which Khadas SBC do you use?
Vim3 Pro
Which system do you use? Android, Ubuntu, OOWOW or others?
Ubuntu 20.04
When the camera is turned on, a white screen appears. Why?
You use v4l2_test to test the camera? If so, you need to switch to framebuffer console with Ctrl+Alt+F1
Why is this screen coming up? As you said, I first come to the framebuffer console by doing ctrl+alt+F1. then I exit this console with ctrl+alt+F7.
The v4l2_test test program only display the image on fb, it may broken the desktop, if you want to use this program please use the server image.