Black screen after boot with DSI screen

[Andz]

Hi,
Tried to experiment with arch arm on raspberry 4. Boots fine but then the screen back light turns off, the screen becomes competely black. I can ssh successfully to raspberry. Arch works from terminal. Tried to enable i2c (is it even necessary with dsi?). No luck. Noticed that journal -b says that it cant find i2c-bcm2708 module, after i try to add the i2c-dev and i2c-bcm2708 modules. It loads i2c-dev successfully.
I am using the waveshare dsi 5inch lcd screen.
Using raspberry official os, screen works out of the box.
Not sure where to go from here, any help appreciated!

[Andz]

With linux-rpi the screen works as expected.
I`ll try to figure out why it isn't so in vanilla. Maybe config.txt contents?

[graysky]

If your screen is not support in the mainline kernel, that would explain it as the linux-rpi branch did. It could be that a needed module for it is not present on the mainline kernel as well. If you're on RPi, I recommend that you run the linux-rpi kernel.