Toradex apalis imx8 lvds display not working

Hi,
I am using apalis imx8 quadmax ixora v1.2 carrier board. I am using boot2qt image to run the qt application. I am not able to see any gui or display on lvds touch screen. Only hdmi display is working and we want both to get displayed. From our side we dont see any overlay files in boot directory to enable the lvds display. We are building the image using yocto build setup. Could you guide us in steps to setup the display in touchscreen lvds.

1 Like

Hello @Mohar ,

To enable a multi-screen setup, there is the guide below by Qt that can help you find a solution.

You have to select the correct mode in /etc/kms.conf as described by Qt in this article:
https://doc.qt.io/qt-5/embedded-linux.html

Give this a try and let us know if you had success.

Best Regards
Kevin

currently the contents of kms.conf is
{
“hwcursor”: false,
“device”: “/dev/dri/card1”
}
what should be added for both lvds and hdmi mode to be on

what should be the mode for lvds. For now only hdmi is working for contents of kms.conf shown below

{
“device”: “/dev/dri/card1”,
“hwcursor”: false,
“pbuffers”: true,
“outputs”: [
{
“name”: “VGA1”,
“mode”: “on”
},
{
“name”: "HDMI-A-1 ",
“mode”: “1024x768”
},
{
“name”: “LVDS1”,
“mode”: “on”
}

I was giving name a “LVDS-1”, mode as “on” in kms.conf file and tried to reboot it but still the lvds display is not showing up

Hi @Mohar ,

it is possible that LVDS is not activated. If you enter the command ls /sys/class/drm/ you should see something related to LVDS.

By the way, are you using wayland?

To get more information you can also use export QT_LOGGING_RULES=qt.qpa.*=true to enable the Qt logging mechanism.

Best Regards
Kevin

card0 card1 card1-HDMI-A-1 card1-LVDS-1 renderD128 renderD129 version
This is the contents of /sys/class/drm

Currently I am getting the qt application gui on hdmi. Am getting linux login screen on lvds but am not getting the gui on lvds.

The GUI is coming up on lvds display when I have removed the hdmi cable. But I need to get both hdmi and lvds display at the same time

On connecting the hdmi cable back to the board, the hdmi display gui is not coming up

Hi @Mohar ,

EGLFS is not as dynamic as you might imagine. It is built to work for static configurations of displays, which is why HDMI is not coming up.

You can try to use clone and see if it works.

{
  "device": "/dev/dri/card0",
  "outputs": [
      { "name": "HDMI1", "mode": "1920x1080" },
      { "name": "LVDS1", "mode": "1920x1080", "clones": "HDMI1" }
 ]
}

Let us know if it worked.

Best Regards
Kevin

Hi,
Any update on the dual dupulicate display? We are able to bring dual extended display by running some qt application source code, but we need duplicate display. Any help on this would be good.
Thanks

We also tried using Etnaviv driver, by giving the line below in local conf file while building the image for imx8 machine we are getting build errors on this saying its not compatible with imx8 machine.

MACHINEOVERRIDES = “:use-mainline-bsp”

Hi @Mohar ,

For further instructions on how to achieve this we refer to the Qt-documentation. They have a specific section that addresses this.

Advanced EGLFS features

In there you should find all you need to achieve it.

Best Regards
Kevin

I tried some links here but am not getting much. Is the dual duplicate display working for you? Did you try on your side ?

Hi @Mohar

did you try the clone approach? Can you confirm?

Can you share some insight in the Qt log that you can see after enabling export QT_LOGGING_RULES=qt.qpa.*=true ?

Best Regards
Kevin

Yes I tried and didnt work. Its showing linux boot2qt shell screens on both the displays which we dont want,its not showing any GUI on both.The log was showing that it cannot create another screen. Just to confirm is the default boot2qt image from toradex easy installer is working for you in case of dual duplicate display? If yes how you fixed it ?

Hi @Mohar ,

Unfortuantely , this exceeds Toradex’s normal support area. I recommend you contact the Qt support for ruther instructions on what is not working in this regard. I am sure the guys from Qt can help to move forward here.

Qt Support Center

Have a nice day.

Best Regards
Kevin