Unsolved HDMI errors while trying to run Qt apps on Raspberry Pi 3B+.

[ak_07]

I am trying to get a simple app to run a my target device, Raspberry Pi 3B+. I tried the Qt Quick example applications Scrollview, Empty and The Qt Widgets application without any changes made to the code. None of these run on the target device. They run fine on the Host. But, return the below errors when run on the target device.

15:31:36: Starting /opt/widget_app/bin/widget_app ...
QStandardPaths: XDG_RUNTIME_DIR not set, defaulting to '/tmp/runtime-root'
Failed to move cursor on screen HDMI1: -13
Failed to move cursor on screen HDMI1: -13
Could not set DRM mode for screen HDMI1 (Permission denied)
Could not queue DRM page flip on screen HDMI1 (Permission denied)

My setup:

• Raspberry Pi 3B+ with Touchscreen connected using HDMI.
• Flashed with Boot to Qt Image created using the following documentation: https://doc.qt.io/QtForDeviceCreation/b2qt-how-to-create-b2qt-image.html
• Followed the above documentation to Configure Qt Creator for Linux Toolchain.
• The Pi is connected to the Host System running Ubuntu 20.04.
• I can SSH into the Pi from Host using the default root login with empty password.
• I have Qt 6.0.3 and Qt Creator 4.14.2 installed via the Open Source Installer.
• Kit settings:

I have tested the connection with the device and it passes with the following output:

Connecting to host...
Checking kernel version...
Linux 5.4.72-v7 armv7l

Checking if specified ports are available...
All specified ports are available.

Checking whether an SFTP connection can be set up...
SFTP service available.

Checking whether rsync works...
rsync is functional.

Device test finished successfully.

I also tried installing with a non root user on the Pi. But then certain permissions are denied by the target when installing the Qt app to Pi from host.

What could be the problem here?

Thanks.