1MP*4 Quadrascopic Monochrome Camera - VIDIOC_STREAMON: Invalid argument

In fact you should connect all four channels, use the following command to test each channel:
python3 arducam_displayer.py -f GREY --width 1280 --height 800 --channel 0
Use --channel to specify the channel to be tested. 0~3

OK. I got it. I’ll try next week.