CM4/IO board: 5" DSI LCD display not working

Diy and Tweaks
1

I have a “CM4/IO board” based setup and just added a Waveshare 5" LCD display (DSI), which is not working. This is System version 3.569 and the touch display plugin is installed. If I transfer the SD card and display to an RPI 4b, the display works. I have tried a fresh installation and reinstalling the plugin, but so far have had no luck. The display is connected to disp1 (have tried disp0) and shows a brief flicker on startup. Are there any special tweaks required for the CM4? I will reach out to Waveshare after New Year’s but thought I would ask here in the meantime.

Cheers,
Soren

2

Adding the following to the config.txt did the trick.

dtoverlay=vc4-kms-v3d
dtoverlay=vc4-kms-dsi-7inch

3

custom settings must be written in userconfig.txt, not in config.txt

if you write them on config.txt, you will lose them after a software update, on userconfig.txt they will be maintained

4

Excellent. Thank you!

I see in the Wiki that the following command can be used to adjust brightness. Could that also be added to the userconfig.txt?

echo X > /sys/class/backlight/rpi_backlight/brightness

5

no, this command must be executed on the OS via terminal or ssh

6

Thanks Darmur. Maybe I missed it, are there other ways to adjust the backlighting?

7

with the official RPi display and some other displays, the brightness can be adjusted in the settings of the touch display plugin.

if you don’t see this option, I think the only way is running the command you mentioned from terminal or ssh

8

Or perhaps an Apple shortcut?