LVDS color problems / settings

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LVDS color problems / settings

Postby kruszi » Mon Jan 09, 2017 4:04 pm


I have a LCD display attatched to my WBQ (DLC1010AZG-T-7). During U-Boot boot I overwrite bootargs with mxcb0:dev=ldb,LDB-WSVGA,if=RGB24
The resolution fits my display (1024x600) perfectly. The display is detected under Ubuntu 12. It only seems that there are problems with the color mode. The colors seem partialy right, but not entirely. Furthermore the display looks very dimmed / gray over all. (Backlight is fully on, no PWM - guaranteed, hard wired to power supply, full brightness white visible when no LVDS data is provided).
See the image for details of wrong color (reference color card).
I suspect this problem to be coming from the "color mode". No matter wheter I use RGB565, RGB666, RGB888 or RGB24 nothing changes.
Unfortunately I can not find a code / documentation which modes are supported / usable on the WBQ (kernel?).
- Where (which file, which repo) is used for the Ubuntu 12 WBQ kernel, where can I find the video modes (and display timing) ?
- How to find out which kernel version is used in Ubunutu 12 WBQ kernel?
- An ideas or suggestions what might be wrong?


See as attatchments: testimage (photo of my LCD, wrong color), reference image (how it should be), and photo of firefox w. wrong colors, please scroll the image to see the application icons also in wrong color

Datasheet Display
IMG_2962.JPG (131.3 KiB) Viewed 1372 times
IMG_2963.JPG (132.06 KiB) Viewed 1372 times
source: wikipedia
PM5544_with_non-PAL_signals.png (26.76 KiB) Viewed 1372 times
Posts: 12
Joined: Wed May 11, 2016 2:33 pm

Re: LVDS color problems / settings

Postby nevmair » Tue Jan 10, 2017 4:42 am

Try this for your display configuration


For video modes and timing:
Not sure where it is in the newer kernels, but in the older versions 3.0.35 it was here

look for this array

static struct fb_videomode ldb_modedb

Posts: 43
Joined: Mon Feb 16, 2015 3:42 pm

Re: LVDS color problems / settings

Postby kruszi » Tue Jan 10, 2017 2:46 pm


thanks for the information. As I accidentally moved the LCD a litte bit suddenly I had a correct image on the screen.
It was a loose contact on the LVDS datalane RED at one of the connectors.

Concerning the DLC1010AZG-T-7 LCD I made a little description of the LVDS activation process ( I hope this will help others activating their LVDS.

Posts: 12
Joined: Wed May 11, 2016 2:33 pm

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