How to modify the panel backlight
First identify the backlight device linked to your panel, thanks to the sysfs:
Board $> 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:
Board $> 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:
Board $> cat /sys/class/backlight/*/max_brightness 255
To get the actual panel backlight value, enter:
Board $> cat /sys/class/backlight/*/actual_brightness 32
Use one of the following commands to quickly test the panel backlight:
Board $> export bl=/sys/class/backlight/5a000000.dsi.0/brightness Board $> # switch on/off test Board $> (while true; do echo 0 > $bl; sleep 0.5; echo 255 > $bl; sleep 0.5; done) Board $> # slow 32-step tests Board $> (i=0; while true; do i=$(((i+32)%256)); echo $i > $bl; sleep 0.5; done) Board $> # fast 1-step test Board $> (i=0; while true; do i=$(((i+1)%256)); echo $i > $bl; done)