Deviceinfo dev touchscreen

From postmarketOS

This page is about deviceinfo_dev_touchscreen from the deviceinfo file.

How to find the touchscreen device name?

Note Note: The deviceinfo_dev_touchscreen property is mostly obsolete - DirectFB can now automatically detect the touchscreen. This works only if the touchscreen sets the INPUT_PROP_DIRECT bit to identify the input device as a touchscreen. Setting the property is only necessary if your touchscreen is not automatically detected.

Initramfs #1 (fastest)

  • Connect to your initramfs via telnet
  • Run ls /dev/input
  • For each device in there, do the following:
    • Run cat /dev/input/$device
    • Tap on the screen and see if you get any output
    • The device where you get output is the touch screen

Initramfs #2

  • Connect to your initramfs via telnet
  • Run ls /dev/input
  • Try out one after another:
    • Change deviceinfo_dev_touchscreen in your deviceinfo
    • Rebuild the deviceinfo package, initramfs and flash:
 pmbootstrap checksum device-wiki-example
 pmbootstrap build --force device-wiki-example
 pmbootstrap initfs # rebuild initramfs
 pmbootstrap flasher boot_kernel

Easy method (you don't need to connect)

  • Turn on your device and open any file manager, for example, Total Commander
  • Go to /dev/input directory
  • For each device in there, try to remove it one by one.
  • When the touch screen stops working, it means that the device you just deleted is the touch screen.
  • To fix the touch screen, reboot the device.

Flashing system + libinput list-devices

Alternatively, run pmbootstrap install and flash the system partition again. Then you can use the program libinput list-devices to get the list of devices - with probably more useful names.

When you have the right device name, put it into your deviceinfo (as outlined above), then re-flash the encrypted system image. It should work now.