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I am running my qml application on a raspberry pi 3. For input I am using a touchscreen.

Normally the touchscreen is working fine. But when I reboot the touchscreen, the qml application gives me the following error message:

evdevtouch: Could not read from input device (No such device)

After this message the qml application does not receive any more events from the touchscreen.

I know that the touchscreen is registered to the system as /dev/input/eventX. When turning off the touchscreen I can see that /dev/input/eventX disappears. And after turning on the touchscreen again I can see /dev/input/eventX again.

With

QT_LOGGING_RULES

I see that the qml application is discovering this device and connecting to it after application start.

But once the device is gone, the application seems not to reconnect again.

Any ideas how I can reconnect to the device again? Or maybe oter ideas?

Kind regards

MHermann
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  • have you tried regularly checking for `/dev/input/eventX` when it disappears? As soon as it reappears, within a time frame, reload your app. – bardao Mar 26 '19 at 23:15
  • That is the workaround I am using at the moment. I restart my app. Is it possible to "reconnect" to the input device in the running app? A friend of me does not have this problem. He has also a qml app running on the same raspberry pi and he says that he does not have done special things. That means when the touchscreen is turned off and then turned on again, the app is working again without problems. – MHermann Mar 27 '19 at 07:09
  • Try libinput instead evdev – eri Mar 29 '19 at 07:07
  • Okay. What do I have to do to use libinput? Only change some settings and/or environment variables? Or do I have to compile the qt again? – MHermann Apr 01 '19 at 05:46

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