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Author Topic: LVDS Display Problems  (Read 116 times)

Offline MTCAT

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LVDS Display Problems
« on: November 24, 2022, 05:57:48 AM »
Hello,

I'm trying to get a PixelQi display (native res 1024x600 with 18 bits per pixel colour depth) to work with a Vortex-DX3 SBC (WinSystems PPM-C412) running directly off the LVDS port of the SBC. I recently got a custom LVDS cable made to hook up the display to the SBC but at the moment all I see on the display are alternating solid colours of red, green, blue, gray and then a stripy sort of black and white pattern, and then it repeats.

I'm using XVesa with TC3.8.4 (2.6.33.3 with real time patch), screen resolution inside /home/tc/.xsession is set to 1024x768x32, with no vga boot codes being used inside extlinux.conf

I also updated the PPM-C412 BIOS as per the cable mfr's recommendation, with no change unfortunately.

I'm not sure if this is a hardware (cabling) or software problem but I've been looking into resolution915.tcz, but unfortunately my graphics chip is not compatible (see attached output of "lspci -v" and "sudo Xvesa -listmodes).

Previously I've been using the VGA output from the PPM-C412 run into an adapter board which outputs LVDS for the PixelQi, this works but I would like to simplify the setup as much as possible and get rid of the VGA to LVDS adapter board if possible.

Interested to hear any ideas/recommendations you might have, I was wondering if Xorg might be more likely to work with the LVDS output?, assuming that this isn't a cabling problem.

WinSystems manual implies that VGA or LVDS operation is selectable inside the BIOS but I can't see that anywhere, apparently the LVDS and VGA outputs can be simultaneously active so I assume that both are on all the time, I don't see how to select one or the other in the BIOS at all, I've also selected panel index [4] inside the BIOS for 1024x600 resolution, and that's about all I'm able to set inside the BIOS for the LCD panel. I'm still waiting to hear back from WinSystems on this as well regarding any possible BIOS actions.

Thanks,

David

Offline MTCAT

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Re: LVDS Display Problems
« Reply #1 on: November 24, 2022, 06:00:30 AM »
Sorry, forgot to attach the files, too early in the morning!, here they are.

Thanks,

David

Offline gadget42

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Re: LVDS Display Problems
« Reply #2 on: November 24, 2022, 08:06:41 AM »
please keep us posted on your progress and solution!
The fluctuation theorem has long been known for a sudden switch of the Hamiltonian of a classical system Z54 . For a quantum system with a Hamiltonian changing from... https://forum.tinycorelinux.net/index.php/topic,25972.msg166580.html#msg166580

Offline curaga

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Re: LVDS Display Problems
« Reply #3 on: November 24, 2022, 08:31:43 AM »
If going to use Xorg, you will have to compile their driver (xf86-video-rdc). IIRC it wasn't very high quality, but it may offer such configs.
The only barriers that can stop you are the ones you create yourself.

Offline MTCAT

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Re: LVDS Display Problems
« Reply #4 on: November 24, 2022, 08:45:36 AM »
Hi curaga and gadget42,

Thanks for the help, is it pretty easy to undo Xorg installation if it doesn't work? I don't want to badly mess up what is mostly working right now.

Regarding xf86-video-rdc to be used with Xorg, there's no tcz in the repository for RDC graphics chips so I would have to make my own, is that correct?

Thanks,

David


Online Juanito

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Re: LVDS Display Problems
« Reply #5 on: November 24, 2022, 09:37:02 AM »

Offline MTCAT

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Re: LVDS Display Problems
« Reply #6 on: November 24, 2022, 10:32:10 AM »
Thank you, I found a xf86-video-rdc driver zipfile on GitHub, looking through the source code, my 2015 device isn't listed, only devices 2010, 2011 and 2012 are coded in, may just have to try it and see what happens I guess. Unless WinSystems can do some magic with the BIOS itself!

Thanks,

David

Offline curaga

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Re: LVDS Display Problems
« Reply #7 on: November 25, 2022, 12:01:48 AM »
That may be an old file, try getting the latest from the manufacturer. "RDC driver for xorg" or similar, they may call it by a different name.

Undoing a Xorg install is very easy, just edit your onboot.lst and reboot.
The only barriers that can stop you are the ones you create yourself.