No display using MIPI DSI on Radxa 5c

[OlivierSC]

Hello,

 

I'm trying to connect a MIPI DSI display.

 

Currently, backlight is working, but not the display in Armbian (Armbian 25.5.1 Noble Gnome).

DTS is loaded and corresponding kernel module panel-simple-dsi is loaded as well.

 

Same DTS works on the official Radxa 5c image (rock-5c_bookworm_kde_b2) (kernel 6.1.43-15)

 

Has anyone faced a similar issue?

 

armbianmonitor -u : https://paste.armbian.com/ocoperohak.yaml

 

Thanks!

 

[laibsch]

I wonder if the ENOENT at around line 493 of your log has anything to do with this.

 

Maybe @schwar3kat has a comment?

[royk]

What does the following command show?
sudo fdtoverlay -v -i /sys/firmware/fdt -o /dev/null /path/to/your_overlay.dtbo

 

panel-simple-dsi ... Expected bpc in {6,8} but got: 0
So possibly the default with the older kernel was by accident correct and now you should define it.

 

And it seems that you use an overlay meant for the 5a on a 5c?

Edited August 16 by royk

[OlivierSC]

Thanks @laibsch and @royk.

 

For now, we’ve managed to get things working by running the latest vendor kernel, but using panel-simple.c from version 6.1.43.

This workaround isn’t ideal, and we’ll try to investigate the root cause once we have more time.

 

As for the log message "Expected bpc in {6,8} but got: 0", it doesn’t appear when using 6.1.43, even though the relevant source code is identical in that part.

[royk]

Try to upload the old and new driver to an AI with you overlay included. Here it gives some suggestions for what you can try. The power sequence seems to be changed with the new driver and it might be too fast for your display. It suggests to put some parameters in the overlay to delay some parts, with higher chance with the first 3:
Under "dsi0_panel: panel@0 {"

prepare-delay-ms = <120>;
reset-delay-ms = <50>;
init-delay-ms = <150>; 

enable-delay-ms = <50>; 
disable-delay-ms = <50>;
unprepare-delay-ms = <120>;