Double input from touchscreen.

[kalbar666]

Hello all,

I am having a problem with set up of the environment around my Qt app on Beaglebone Black. Embedded Linux system got created with Yocto project. Touchscreen seems to be working as I can calibrate it with ts_calibrate and later on successfully test it with ts_test.

My Qt application is just a simple GUI with 2 buttons and it does show up successfully and normal mouse is working as it should. Problem appears whenever I try using touchscreen. I do experience a cursor movement as if it was sourced from two places at the same time - one source perfectly calibrated working exactly as it should, the second completely uncalibrated as if it was a raw a reading. Both sources meet perfectly in the upper left corner of the screen.

Application "buttons" is started from a simple script where I try to initialize environment variables before execution. I am trying to use linuxfb platform with tslib. I do not have eglfs platform installed in my Qt environment.

#!/bin/bash

export QT_QPA_EGLFS_DISABLE_INPUT=1
export QT_QPA_FB_DISABLE_INPUT=0

export QT_QPA_EGLFS_TSLIB=1
export QT_QPA_FB_TSLIB=1

export QT_QPA_GENERIC_PLUGINS=tslib:/dev/input/event0
export QT_QPA_PLATFORM=linuxfb:fb=/dev/fb0
export QT_PLUGIN_PATH=/usr/lib/qt/plugins

export QT_QPA_EVDEV_TOUCHSCREEN_PARAMETERS=""
export QT_QPA_EVDEV_KEYBOARD_PARAMETERS=""
#export QT_QPA_EVDEV_MOUSE_PARAMETERS=""

export TSLIB_TSEVENTTYPE='INPUT'
export TSLIB_CALIBFILE='/etc/pointercal'
export TSLIB_CONFFILE='/etc/ts.conf'
export TSLIB_CONSOLEDEVICE='none'
export TSLIB_FBDEVICE='/dev/fb0'
export TSLIB_PLUGINDIR='/usr/lib/ts'
export TSLIB_TSDEVICE='/dev/input/event0'

/home/root/buttons source -platform linuxfb -plugin tslib
#/home/root/buttons source

exit 0

My input devices show up as follow, where event0/mouse0 is the touch device over USB:

root@bbb:~# ls -all /dev/input/by-id
total 0
drwxr-xr-x 2 root root 180 Sep 12 02:43 .
drwxr-xr-x 4 root root 260 Sep 12 02:43 ..
lrwxrwxrwx 1 root root   9 Sep 12 01:35 usb-Logitech_USB_Keyboard-event-if01 -> ../event2
lrwxrwxrwx 1 root root   9 Sep 12 01:35 usb-Logitech_USB_Keyboard-event-kbd -> ../event1
lrwxrwxrwx 1 root root   9 Sep 12 02:43 usb-MOSART_Semi._2.4G_Keyboard_Mouse-event-kbd -> ../event3
lrwxrwxrwx 1 root root   9 Sep 12 02:43 usb-MOSART_Semi._2.4G_Keyboard_Mouse-if01-event-mouse -> ../event4
lrwxrwxrwx 1 root root   9 Sep 12 02:43 usb-MOSART_Semi._2.4G_Keyboard_Mouse-if01-mouse -> ../mouse1
lrwxrwxrwx 1 root root   9 Sep 12 01:35 usb-WWW.PowerMCU.COM_Multi_Media_Development_Board_V1.0_6D8413964957e-event-mouse -> ../event0
lrwxrwxrwx 1 root root   9 Sep 12 01:35 usb-WWW.PowerMCU.COM_Multi_Media_Development_Board_V1.0_6D8413964957e-mouse -> ../mouse0

How to disable this erratic cursor source? How to diagnose the problem?

I am very new to the embedded Linux development, so any guidance on would be really appreciated.