Approved version. Approved on: 16:44, 18 February 2019
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Version of 09:31, 7 October 2019 by Philippe Cornu
- Last edited 11 months ago ago
How to modify the panel backlight
First identify the backlight device linked to your panel, thanks to the sysfs:
ls /sys/class/backlight 5a000000.dsi.0
In the above example, there is a single entry named "5a000000.dsi.0", which is replaced by "*" in the below command.
To adjust the panel backlight, enter the following command:
echo 32 > /sys/class/backlight/*/brightness # set the dsi panel backlight to the value 32
Note: Only values between 0 and max_brightness must be used.
To get the maximum panel backlight value, enter:
cat /sys/class/backlight/*/max_brightness 255
To get the actual panel backlight value, enter:
cat /sys/class/backlight/*/actual_brightness 32
Use one of the following commands to quickly test the panel backlight:
export bl=/sys/class/backlight/5a000000.dsi.0/brightness # switch on/off test (while true; do echo 0 > $bl; sleep 0.5; echo 255 > $bl; sleep 0.5; done) # slow 32-step tests (i=0; while true; do i=$(((i+32)%256)); echo $i > $bl; sleep 0.5; done) # fast 1-step test (i=0; while true; do i=$(((i+1)%256)); echo $i > $bl; done)