Multiple screens on Qt Automotive with iMX6

Isaias

Hello,

Following Building Your Own Embedded Linux Image, I was able to create a Qt Automotive image and the Neptune demo works fine

But now I would like to have two screen working together with the Neptune demo.

I modified my local.conf to remove X11 and wayland in order to work only with EGLFS

DISTRO_FEATURES_remove = "X11 wayland"

I also modified my u-boot enviroment variables to set up my two screens (HDMI and LVDS)

setenv vidargs 'video=mxcfb0:dev=ldb video=mxcfb1:dev=hdmi,1280x1024M@60,if=RGB24 video=mxcfb2:off video=mxcfb3:off fbmem=32M'

I can see the neptune in my HDMI monitor (fb2) but a black in my LVDS screen (fb0)

but when I execute:

cat /dev/urandom > /dev/fb0

it does work, I can see the random pixels being painted

But in my app when I execute:

    QList<QScreen *> screens = QGuiApplication::screens();
    printf("Screens = %d\n", screens.count());

I only get one screen and when I run qtdiag I get the next:

Screens: 1, High DPI scaling: inactive
# 0 "" Depth: 16 Primary: yes
  Manufacturer:
  Model:
  Serial number:
  Geometry: 1920x720+0+0 Available: 1920x720+0+0
  Physical size: 487.68x182.88 mm  Refresh: 62 Hz Power state: 0
  Physical DPI: 100,100 Logical DPI: 100,100 Subpixel_None
  DevicePixelRatio: 1 Pixel density: 1
  Primary orientation: 2 Orientation: 2 Native orientation: 0 OrientationUpdateMask: 0

It looks like Qt Embedded is only detecting my first screen (fbo)

Does somebody has had experience with multiple screen working together?
Am I missing some configuration file?

My intention was to configre neptune to something like this: Neptune 3 UI - Configuring Screens on Embedded Linux

My HW is:

Apalis iMX6
Apalis Evaluation Board

root@b2qt-apalis-imx6:~# uname -a
Linux b2qt-apalis-imx6 4.1.44-2.7.5+g18717e2b1ca9 #1 SMP Fri Feb 22 10:41:34 CST 2019 armv7l armv7l armv7l GNU/Linux

Thanks

tomasz3dk

@Isaias Did you try to set QT_QPA_EGLFS_FB like it's in manual https://doc.qt.io/qt-5/embedded-linux.html ?

Isaias

Hello @tomasz3dk

I can run the Qt Neptune demo or other Qt app in one screen or the other, even both at the same time, setting QT_QPA_EGLFS_FB to the correct fb before executing the app

But my final intention is to modify the Neptune configuration to work something like this Neptune 3 UI - Configuring Screens on Embedded Linux

It looks like I am missing to set up a configuration for the Qt Embedded Stack to detect both screens but I don't know.

scbyun

Hello everyone
I have the same problem.
Please comment if you know how to solve it.

Bjorn92

Hi @Isaias ,

I have achieved to run two displays (LVDS + HDMI) using Wayland Weston, and running an instance of Weston in clone-mode:

/usr/bin/weston --modules=systemd-notify.so --tty=1 --device=/dev/fb0,/dev/fb2 --clone-mode

Here, the content of fb0 is cloned to fb2.

It works, but on my SoM (i.MX6 based), I now experience severe lag on the LVDS screen and the touch inputs are also delayed.
Additionally, I had to tune down the HDMI resolution to 900x600 to get it to work.

On my SoM, using DRM/KMS is not an option, since my kernel version does not support it. I use fbdev instead.

Maybe this helps a bit. If anybody has another solution, please share!