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Inverted x-axis on TFT LCD



  • I'm attempting to setup a TFT LCD display connected to a BeagleBoneBlack RevC using just the framebuffer via Qt 5.12.3. I can't for the life of me figure out WHY the Qt application and/or the framebuffer is inverting my application's GUI though. I have looked into setting /sys/class/graphics/fb0 invert and rotate but they're seemingly not supported.

    I started by getting the dtbo configured for the LCD, which is working fine. I can cat /dev/urandom > /dev/fb0 and see random noise, and if I let lightdm run, it will display properly.
    normal

    I then moved on to compiling and running my application. It runs just fine, but when it displays it displays completely inverted on the x-axis.
    inverted

    Then even after I close that application, and start lightdm again, it too is inverted?
    inverted_x

    It also happens when I let X11 handle the fb0 device, but if I let SSH forwardX to my host, then it displays properly?

    Environment:
    Linux beaglebone 4.4.30-ti-r64 #1 SMP Fri Nov 4 21:23:33 UTC 2016 armv7l GNU/Linux
    Debian GNU/Linux 8 (jessie)