Porting from Morty to Dunfell: LVDS split-mode not working

Technical Support
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1

Hello!

In Morty (Toradex 2.7, kernel 4.1) we used device tree overlays to support different displays (Toradex introduced them later).
After porting to Dunfell (Toradex 5.x.y, kernel 5.4), the split-mode does not work anymore, there is no image at all.
Smaller displays (single channel LVDS) and HDMI work fine.

In split-mode, there is a signal on the LVDS output lines, but it looks wrong on the oscilloscope. So there seems to be a problem with the clock / data generation.

The resulting frame buffer configuration looks correct for me:

mode "1920x1080-60"
	# D: 142.005 MHz, H: 66.669 kHz, V: 60.062 Hz
	geometry 1920 1080 1920 1080 32
	timings 7042 100 100 10 10 10 10
	accel false
	rgba 8/16,8/8,8/0,8/24
endmode

The device tree of the running system (dtbo applied):
dunfell.dts (91.4 KB)
The configured display is “g156hcel01”, not “1920x1080”

Any suggestion?

Thanks!

2

Hello @sst ,

Greetings from Toradex Community!

Between Toradex 2.7 and Toradex 5.x.y, we have changed the display server protocol that we used to natively support (starting with our BSP 4.0) as NXP no longer supports X or Framebuffer. So, instead, now we opt to use Wayland/Weston, which is what the entire industry is moving forward towards as a standard.

You can find more information on how to adjust the display timing, resolution etc. in this link here.

I hope this helps. Have a nice rest of the week!

Best Regards,
Janani

3

The problem was not the device. Other panels (also dual-LVDS) work fine also with the new OS.
It’s not clear, why the one panel works with the old system only, but this thread can be closed.