QML on Raspberry

Raviphulsundar

Qt version: Qt 5.6.2
Simple Qt program without QML works fine with "-platform linuxfb"
but Qt+QML program not working.
No error is displayed and keyboard & mouse don't responds.

sierdzio

This is not relevant for non-accelerated platforms, for example the ones using the LinuxFB plugin, which is meant for software-based rendering only. This means Qt Quick 2 is not functional in such a setup as it depends on OpenGL for rendering.

Taken from: http://doc.qt.io/archives/qt-5.6/embedded-linux.html#configuring-a-specific-device

It looks like you need to use -platform eglfs instead.

Raviphulsundar

I tried with -platform eglfs
it is not working

following are last few lines I got from strace command

open("/dev/tty", O_RDONLY|O_LARGEFILE|O_CLOEXEC) = 5
fcntl64(5, F_SETFD, FD_CLOEXEC) = 0
close(5) = 0
write(2, "Could not find DRM device!\n", 27) = 27
rt_sigprocmask(SIG_UNBLOCK, [ABRT], NULL, 8) = 0
tgkill(199, 199, SIGABRT) = 0
--- SIGABRT {si_signo=SIGABRT, si_code=SI_TKILL, si_pid=199, si_uid=0} ---
+++ killed by SIGABRT +++

sierdzio

You probably need to install missing dependencies (if any) and compile the EGLFS platform plugin for Qt.

See this guide: https://wiki.qt.io/RaspberryPi2EGLFS

Raviphulsundar

Following plugins are installed in /usr/lib/qt/plugins/platforms/
libqeglfs.so libqlinuxfb.so libqminimalegl.so libqminimal.so libqoffscreen.so libqxcb.so

Raviphulsundar

make command output
$ make
./buildroot-2017.02.2/output/host/usr/bin/arm-buildroot-linux-gnueabihf-g++ -c -pipe -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os --sysroot=./buildroot-2017.02.2/output/host/usr/arm-buildroot-linux-gnueabihf/sysroot -O2 -O3 -std=gnu++0x -Wall -W -D_REENTRANT -fPIC -DQT_NO_DEBUG -DQT_QUICK_LIB -DQT_GUI_LIB -DQT_QML_LIB -DQT_NETWORK_LIB -DQT_CORE_LIB -I. -I ./buildroot-2017.02.2/output/host/usr/arm-buildroot-linux-gnueabihf/sysroot/usr/include/qt5 -I ./buildroot-2017.02.2/output/host/usr/arm-buildroot-linux-gnueabihf/sysroot/usr/include/qt5/QtQuick -I ./buildroot-2017.02.2/output/host/usr/arm-buildroot-linux-gnueabihf/sysroot/usr/include/qt5/QtGui -I ./buildroot-2017.02.2/output/host/usr/arm-buildroot-linux-gnueabihf/sysroot/usr/include/qt5/QtQml -I ./buildroot-2017.02.2/output/host/usr/arm-buildroot-linux-gnueabihf/sysroot/usr/include/qt5/QtNetwork -I ./buildroot-2017.02.2/output/host/usr/arm-buildroot-linux-gnueabihf/sysroot/usr/include/qt5/QtCore -I. -I ./buildroot-2017.02.2/output/host/usr/mkspecs/devices/linux-buildroot-g++ -o main.o main.cpp
./buildroot-2017.02.2/output/host/usr/bin/rcc -name qml qml.qrc -o qrc_qml.cpp
./buildroot-2017.02.2/output/host/usr/bin/arm-buildroot-linux-gnueabihf-g++ -c -pipe -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os --sysroot=./buildroot-2017.02.2/output/host/usr/arm-buildroot-linux-gnueabihf/sysroot -O2 -O3 -std=gnu++0x -Wall -W -D_REENTRANT -fPIC -DQT_NO_DEBUG -DQT_QUICK_LIB -DQT_GUI_LIB -DQT_QML_LIB -DQT_NETWORK_LIB -DQT_CORE_LIB -I. -I./buildroot-2017.02.2/output/host/usr/arm-buildroot-linux-gnueabihf/sysroot/usr/include/qt5 -I./buildroot-2017.02.2/output/host/usr/arm-buildroot-linux-gnueabihf/sysroot/usr/include/qt5/QtQuick -I ./buildroot-2017.02.2/output/host/usr/arm-buildroot-linux-gnueabihf/sysroot/usr/include/qt5/QtGui -I./buildroot-2017.02.2/output/host/usr/arm-buildroot-linux-gnueabihf/sysroot/usr/include/qt5/QtQml -I./buildroot-2017.02.2/output/host/usr/arm-buildroot-linux-gnueabihf/sysroot/usr/include/qt5/QtNetwork -I./buildroot-2017.02.2/output/host/usr/arm-buildroot-linux-gnueabihf/sysroot/usr/include/qt5/QtCore -I. -I./buildroot-2017.02.2/output/host/usr/mkspecs/devices/linux-buildroot-g++ -o qrc_qml.o qrc_qml.cpp
./buildroot-2017.02.2/output/host/usr/bin/arm-buildroot-linux-gnueabihf-g++ --sysroot=./buildroot-2017.02.2/output/host/usr/arm-buildroot-linux-gnueabihf/sysroot -Wl,-O1 -o Rectangle main.o qrc_qml.o -lQt5Quick -L./buildroot-2017.02.2/output/host/usr/arm-buildroot-linux-gnueabihf/sysroot/usr/lib -lQt5Gui -lQt5Qml -lQt5Network -lQt5Core -lrt -ldl -lGLESv2 -lpthread

Raviphulsundar

One more error I found through strace command

"This plugin does not support cre"
"Failed to create OpenGL context"

sierdzio

I don't know this error, sorry. So I am only guessing, but: are you sure you have all dependencies installed, including all OpenGL drivers?

Raviphulsundar

Yes, I've installed all the dependencies.

What is the meaning of
could not open DRM device error

jeremy_k

@Raviphulsundar This looks like an error reported by the eglfs plugin, but the details aren't clear to me. Can you try running it with the qt.qpa.eglfs.kms logging category enabled?

ie $ QT_LOGGING_RULES="qt.qpa.eglfs.kms=true" program -platform eglfs

Raviphulsundar

#export QT_LOGGING_RULES=qt.qpa.*=true
#./Rectangle -platform eglfs
qt.qpa.egldeviceintegration: EGL device integration plugin keys: ("eglfs_kms_egldevice","eglfs_kms","eglfs_X11")
qt.qpa.egldeviceintegration: EGL device integration plugin keys (sorted): ("eglfs_kms","eglfs_kms_egldevice","eglfs_X11")
qt.qpa.egldeviceintegration: Trying to load device EGL integration "eglfs_kms"
qt.qpa.egldeviceintegration: Using EGL device integrtion "eglfs_kms"
qt.qpa.input: udev device discovery for type QFlags(0x10)
qt.qpa.input: Found matching devices ()
qt.qpa.eglfs.kms: Found the following video devices ()
Could not find DRM device!
Aborted

jeremy_k

It looks like querying libudev for DRM video devices is coming up empty. Is there anything in the /sys/class/drm/ directory on the target?

From the Qt platform plugin side, the code of interest is QDeviceDiscoveryUDev::scanConnectedDevices() in qtbase/src/platformsupport/devicediscovery/qdevicediscovery_udev.cpp

Raviphulsundar

$ls /sys/class/drm
version
$cat /sys/class/drm/version
drm 1.1.0 20060810

$ls /lib/modules/4.4.43-v7/kernel/drivers/gpu/drm/
drm_mipi_dsi.ko panel/ udl/ vc4/

$lsmod
// No drm module is loaded, However DRM module is selected in Kernel configuration.

Raviphulsundar

Now I've recompiled Kernel with
CONFIG_DRM=m
instead of
CONFIG_DRM=y

Now,
$ls /sys/class/ <---- no drm directory
$ls /lib/modules/4.4.43-v7/kernel/drivers/gpu/drm/
drm_kms_helper.ko drm.ko drm_mipi_dsi.ko panel udl vc4

$lsmod -------> no drm module loaded
#modprobe drm
//DRM module loaded

And now
$ls /sys/class/drm
version <----- Only version file

$cat /sys/class/drm/version
drm 1.1.0 20060810

jeremy_k

@Raviphulsundar I suspect you need to get the Broadcom driver for the GPU. It might already be on the system, waiting to be loaded. Unfortunately I don't know what it is called. Have you checked raspberrypi.org?

Raviphulsundar

@jeremy_k, I have checked in RaspberryPi forum for this pbm related to DRM. That thread is still unsolved.

Regarding Broadcom driver for the GPU, I could not found it in Linux config.

One thing I observed is drm module is not loading at boot time.
Does it mean that Frame Buffer modules are selected instead of DRM ?

jeremy_k

Unfortunately I don't have a pi to look at. Does the Raspbian distribution include X or some sort of gui? You can grab a copy of that, boot it, and see which modules are loaded.

There's also this article about getting Qt to run with Arch on the pi 3: http://www.chaos-reins.com/2017-01-13-qt-pi3-arch-aarch64/

Raviphulsundar

@jeremy_k ,

Initially I was trying with ARM32 installation.

Then I tried with ARM64 with BCM2837 dts. But what I observed in Buildroot that,
When I select AARCH64 (ARM64), Buildroot don't allow to select Qt Quick Controls.

Is there any issue pending with "AMR64 & QtQuick combination". ?

jsulm

@Raviphulsundar Do you have ARM64 Qt build?
Is your target system running an OS built for ARM64?

Raviphulsundar

@jsulm I've OS Built for ARM64 with Qt 5.6 but without Quick controls & QML.