Qt + Raspbian with LCD display module(4DPi-32) primary display problem

afsay

Hello,

I installed Qt in my Raspbian following this tutorial.

I am using Raspbian 2015-02-16-raspbian-wheezy.img image. I successfully compiled Qt platform and I am able to run Qt applications in my Raspberry Pi.

However, there is a problem when I use 4DPi-32 display module as primary display instead of HDMI output. I installed 4DPi-32's kernel driver and display module became primary display for Raspberry Pi, HDMI monitor is blank and desktop is displayed on 4DPi-32 display module. Things get weird after this point. Applicaitons I compiled for Qt pops up on HDMI display instead of 4DPi-32 display module. Gnome desktop's primary display is 4DPi-32 but for Qt applications primary display is HDMI output. I asked help from 4D systems, but unfortunately they couldn't help. Their "support team" asked me to look for the answer in Qt and Raspberry Pi forum :)

Following are additional information about my platform, warning and configuration messages. Please help, Thank you.

This is a warning message I get when I ran Qt Application
"This plugin does not support propagateSizeHints()"

These are supported platforms when I run Qt application in Raspberry Pi
eglfs
linuxfb
minimal
minimalegl

** This is my Qt configuration:
**Building on: linux-g++-64
Building for: devices/linux-rasp-pi-g++
Architecture: arm, features:
Host architecture: unknown, features:
Platform notes:

        - Also available for Linux: linux-kcc linux-icc linux-cxx

qmake vars .......... styles += mac fusion windows DEFINES += QT_NO_LIBUDEV DEFINES += QT_NO_XCB PRECOMPILED_DIR = .pch/release-shared OBJECTS_DIR = .obj/release-shared MOC_DIR = .moc/release-shared RCC_DIR = .rcc/release-shared UI_DIR = .uic/release-shared sql-drivers = sql-plugins = sqlite qmake switches .........
Build .................. libs tools
Configuration .......... cross_compile qpa largefile neon pcre minimal-config small-config medium-config large-config full-config evdev linuxfb c++11 accessibility egl eglfs openvg opengl opengles2 shared qpa reduce_exports reduce_relocations clock-gettime clock-monotonic mremap getaddrinfo ipv6ifname getifaddrs inotify system-png png freetype system-zlib nis iconv rpath concurrent audio-backend v8 release
Debug .................. no
C++11 support .......... yes
pkg-config ............. yes
Qt D-Bus module ........ no
Qt Concurrent code ..... yes
Qt GUI module .......... yes
Qt Widgets module ...... yes
JavaScriptCore JIT ..... To be decided by JavaScriptCore
QML debugging .......... yes
PCH support ............ no
iWMMXt support ......... no
NEON support ........... yes
IPv6 ifname support .... yes
getaddrinfo support .... yes
getifaddrs support ..... yes
Accessibility .......... yes
NIS support ............ yes
CUPS support ........... no
Iconv support .......... yes
Glib support ........... no
GStreamer support ...... no
PulseAudio support ..... no
Large File support ..... yes
GIF support ............ plugin
JPEG support ........... plugin (qt)
PNG support ............ yes (system)
zlib support ........... system
Session management ..... auto
libudev support ........ no
Use system proxies ..... no
OpenGL support ......... yes (OpenGL ES 2.x)
OpenVG support ......... yes
XShape support ......... auto
XVideo support ......... auto
XSync support .......... auto
Xinerama support ....... runtime
Xcursor support ........ runtime
Xfixes support ......... runtime
Xrandr support ......... runtime
Xi support ............. runtime
Xi2 support ............ auto
MIT-SHM support ........ auto
FontConfig support ..... no
XKB Support ............ auto
GTK theme support ...... no
SQLite support ......... plugin (qt)
OpenSSL support ........ no
Alsa support ........... no
libICU support ......... no
PCRE support ........... qt
Xcb support ............ no
Xrender support ........ no
EGLFS support .......... yes
DirectFB support ....... no
LinuxFB support ........ yes
KMS support ............ no

afsay

Hello,

I solved the problem.
Qt that I cross-compiled for raspberry pi was lack of xcb platform support. If xcb is not added into Qt configuration before cross-compiling it, Qt applications cannot communicate with X11 of Linux. And problem occurs here. It seems like kernel driver for 4DPi-32 is designed for X11, so desktop is running well on 4DPi-32 display. Qt needs to be cross-compiled with xcb support so Qt applications can run on 4DPi-32 on X11 desktop environment. If xcb doesnt exist Qt applicaiton runs with other supported platforms which goes through HDMI output. These platforms are "eglfs, linuxfb, minimal, minimalegl".

To activate xcb in Qt, -qt-xcb configuraiton option must be added to configure command of Qt cross-compile process.

Thats all, hope this piece of information will be helpful to other people who have similar problem.

paavo91

Hi! Could you tell how to add this option to configure?
My config is:

./configure -release -opengl es2 -device linux-rasp-pi2-g++ -device-option CROSS_COMPILE=/home/pawel/raspi/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian/bin/arm-linux-gnueabihf- -sysroot ~/raspi/sysroot -opensource -confirm-license -make libs -prefix /usr/local/qt5pi -extprefix /home/pawel/raspi/qt5pi -hostprefix /home/pawel/raspi/qt5 -v

I am using LCD 3.5 via SPI and I cant see Qt apps on it but on HDMI.
Thanks

Sanjayshekar

Hello Paavo,
We you able to display QT app on 3.5 inch screen?? if yes, what was the solution??

Even for me I am facing the same problem, QT always comes up on HDMI.

Please suggest.

Regards,
Sanju