by cross compilling the screen of rapberrypi2 does not show anything



  • I try to cross compile qt5.5 auf raspberrypi 2 with this tutorial (https://wiki.qt.io/RaspberryPi2EGLFS) .the configuration , make&make install are done
    but get trouble by running the target.als indication i have cross-compile per ssh and i get following error:

    pi@raspberrypi:~ $ ./qopenglwidget
    \0Unable to query physical screen size, defaulting to 100 dpi.
    To override, set QT_QPA_EGLFS_PHYSICAL_WIDTH and QT_QPA_EGLFS_PHYSICAL_HEIGHT (in millimete
    rs).
    QOpenGLFramebufferObject: Framebuffer incomplete attachment.

    what may i have to do?



  • well i am not sure but , i think you should update your .bashrc file and set these parameters[QT_QPA_EGLFS_PHYSICAL_WIDTH, QT_QPA_EGLFS_PHYSICAL_HEIGHT, QT_QPA_EGLFS_DEPTH]. please notify if it worked or if you had already solved please share the solution.



  • I am facing same issue with lcd touch with pi2. Can not open QDialog app. But some graphics examples from /opt/vc/src works fine on screen.



  • As mentioned above you should set the environment variables (see also http://doc.qt.io/qt-5/embedded-linux.html#eglfs).
    Another thing you could try is to extend the graphical memory (in config.txt or using raspi-config). I got often black screens when running Qt applications on the RasPi before extending the memory from 64 to 256 MB. (The physical memory is shared with the GPU and you can configure how much shall be reserved as GPU memory).



  • Hi!
    I cross compiled Qt on Raspberry too, but my problem is that I can't see Qt apps on LCD connected by SPI. I can see apps only on screen connected by HDMI.


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