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Fixing Auto-Rotate screen orientation on PostmarketOS devices running MATE DE

Raju Vindane

Raju Vindane

• 3 min read
Fixing Auto-Rotate screen orientation on PostmarketOS devices running MATE DE

I have been using my Samsung Galaxy Tab A (2015) with PostmarketOS on and off since last year. It serves as a really good e-book reader with KOReader installed on it.

Have tried phosh and plasma-mobile on it, works nicely but slows the device down heavily (2 GB RAM and old processor) so I use MATE Desktop environment on it.

Lately I have started using this tablet along with my laptop as a second screen for work. And it has been working super nicely for that. The only issue being that I have to manually rotate the screen to landscape every time I reboot the device. It resets the screen orientation to portrait after a reboot. So I went through the pmOS wiki and a neat nice hack documented there worked very well for me.

First we will test if the auto-rotate sensor works and if we can read values from it. So we install some basic necessary packages

$ sudo apk add xrandr xinput inotify-tools iio-sensor-proxy

Enable the service for iio-sensor-proxy 

sudo rc-update add iio-sensor-proxy

Reboot the device.

Now in the device terminal start the sensor monitor-sensor

user@samsung-gt58 ~> monitor-sensor
    Waiting for iio-sensor-proxy to appear
+++ iio-sensor-proxy appeared
=== Has accelerometer (orientation: normal, tilt: vertical)
=== Has ambient light sensor (value: 5.000000, unit: lux)
=== No proximity sensor
=== No compass
    Light changed: 14.000000 (lux)
    Accelerometer orientation changed: left-up
    Tilt changed: tilted-down
    Light changed: 12.000000 (lux)
    Tilt changed: vertical
    Light changed: 13.000000 (lux)
    Light changed: 11.000000 (lux)
    Light changed: 13.000000 (lux)
    Accelerometer orientation changed: normal
    Light changed: 5.000000 (lux)
    Light changed: 6.000000 (lux)
    Light changed: 5.000000 (lux)
    Accelerometer orientation changed: right-up
    Light changed: 3.000000 (lux)
    Light changed: 4.000000 (lux)
    Light changed: 5.000000 (lux)
    Light changed: 12.000000 (lux)
    Tilt changed: tilted-down
    Light changed: 19.000000 (lux)
    Accelerometer orientation changed: bottom-up
    Tilt changed: vertical
    Light changed: 1.000000 (lux)
    Light changed: 2.000000 (lux)
    Light changed: 4.000000 (lux)
    Accelerometer orientation changed: right-up
    Tilt changed: tilted-down
    Light changed: 11.000000 (lux)
    Accelerometer orientation changed: normal
    Tilt changed: vertical
    Tilt changed: tilted-down
    Light changed: 18.000000 (lux)
    Light changed: 21.000000 (lux)
    Light changed: 22.000000 (lux)
    Light changed: 19.000000 (lux)
    Accelerometer orientation changed: left-up
    Light changed: 17.000000 (lux)
    Tilt changed: vertical
    Light changed: 14.000000 (lux)
    Tilt changed: tilted-down
    Light changed: 16.000000 (lux)
    Light changed: 18.000000 (lux)
    Light changed: 17.000000 (lux)
    Light changed: 18.000000 (lux)
    Light changed: 17.000000 (lux)
    Light changed: 18.000000 (lux)
    Light changed: 17.000000 (lux)
    Light changed: 18.000000 (lux)
    Light changed: 17.000000 (lux)

As you can see we can read the rotation values from the sensor as I am rotating the tablet in different orientations.

Now we just need to use a script which changes the screen orientation using xrandr according to the sensor value. 

#!/bin/sh

killall monitor-sensor
monitor-sensor > /dev/shm/sensor.log 2>&1 &

while inotifywait -e modify /dev/shm/sensor.log; do

  ORIENTATION=$(tail /dev/shm/sensor.log | grep 'orientation' | tail -1 | grep -oE '[^ ]+$')

  case "$ORIENTATION" in

    normal)
      xrandr -o normal
      xinput set-prop "Goodix Capacitive TouchScreen" "Coordinate Transformation Matrix" 1 0 0 0 1 0 0 0 1
      ;;
    left-up)
      xrandr -o left
      xinput set-prop "Goodix Capacitive TouchScreen" "Coordinate Transformation Matrix" 0 -1 1 1 0 0 0 0 1
      ;;
    bottom-up)
      xrandr -o inverted
      xinput set-prop "Goodix Capacitive TouchScreen" "Coordinate Transformation Matrix" -1 0 1 0 -1 1 0 0 1
      ;;
    right-up)
      xrandr -o right
      xinput set-prop "Goodix Capacitive TouchScreen" "Coordinate Transformation Matrix" 0 1 0 -1 0 1 0 0 1
      ;;

  esac
done

auto-rotate-screen.sh

You need to replace the name of your touch input device in the script, you can get the name by using xinput --list , make sure to type this on the device terminal. 

user@samsung-gt58 ~> xinput --list
* Virtual core pointer                    	id=2	[master pointer  (3)]
*   * Virtual core XTEST pointer              	id=4	[slave  pointer  (2)]
*   * Zinitix Capacitive TouchScreen          	id=10	[slave  pointer  (2)]
*   * Toad One Plus                           	id=12	[slave  pointer  (2)]
* Virtual core keyboard                   	id=3	[master keyboard (2)]
    * Virtual core XTEST keyboard             	id=5	[slave  keyboard (3)]
    * GPIO Buttons                            	id=6	[slave  keyboard (3)]
    * pm8941_pwrkey                           	id=7	[slave  keyboard (3)]
    * pm8941_resin                            	id=8	[slave  keyboard (3)]
    * Zinitix Capacitive TouchScreen          	id=11	[slave  keyboard (3)]
    * samsung-a2015 Headset Jack              	id=9	[slave  keyboard (3)]

In our script here we are using a Zinitix capacitive screen, it will be different for yours.

Once your script is ready with the correct touchscreen name. Save and make the script executable. chmod +x auto-rotate-screen.sh

Then test your script in your terminal ./auto-rotate.sh , stop the script using Ctrl + C

Now we need add this script to auto-start. On MATE DE you can go to System > Control Center > Startup Applications, then click on Custom Add button, browse the script location, give it a name and then click on Add button.

Now reboot the tablet/device, login and see the auto rotation working.

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  1. Auto-Rotation wiki article on PostmarketOS Wiki https://wiki.postmarketos.org/wiki/Auto-rotation
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