Catching GPIO button events

ivd0

I need to catch GPIO button key presses in a Qt/QML application running on an Embedded Linux board.
System-wise, events are recognized by evtest, but after installing event filter via installEventFilter() on QGuiApplication I only get QEvent::SockAct events, twice per press.
Probably Qt listens on file descriptor and gets notifications, but they are not transformed into QKeyEvent.

I'm running the app with the following variables set:

export QWS_KEYBOARD="LinuxInput:/dev/input/event2"
export QT_QPA_EVDEV_KEYBOARD_PARAMETERS=/dev/input/event2

They have some effect at least:

qt.qpa.input: Adding keyboard at "/dev/input/event2"
qt.qpa.input: Try to create keyboard handler for "/dev/input/event2" ""
qt.qpa.input: Opening keyboard at "/dev/input/event2"
qt.qpa.input: Create keyboard handler with for device "/dev/input/event2"
qt.qpa.input: Unload current keymap and restore built-in
qt.qpa.input: numlock=0 , capslock=0, scrolllock=0
qt.qpa.input: evdevmouse: Using device discovery

But apparently this is not enough. Do I have to explicitly listen on /dev/iput/event2 device, or is there an easy way to re-use Qt key events?

Thanks!