If the rotary encoder seems to produce two events for each movement, it may be that your unit is part of an older batch that used a different rotary encoder.

The fix for that is to create the following file in /etc/modprobe.d/rotary-encoder.conf:

options rotary_encoder force_steps_per_period=1

Note: The following commands should be run as root on the release image.

You can create it by running:

echo "options rotary_encoder force_steps_per_period=1" > /etc/modprobe.d/rotary-encoder.conf

Then you will need to reload the driver:

modprobe -r rotary_encoder

modprobe rotary_encoder

Testing the changes

If your board is currently on a development image, you can use evtest to check if the changes took effect.

root@imx8qxp-d7:~# evtest
No device specified, trying to scan all of /dev/input/event*
Available devices:
/dev/input/event0:  system-controller:keys
/dev/input/event1:  d7-buttons
/dev/input/event2:  rotary-encoder
/dev/input/event3:  Atmel maXTouch Touchscreen
Select the device event number [0-3]:

Select device 2 (the rotary encoder) and rotate it. One detent should produce one event, similar to this:

Event: time 1749712791.920969, type 2 (EV_REL), code 8 (REL_WHEEL), value -1

Event: time 1749712791.920969, -------------- SYN_REPORT ------------