Turn off display to save battery

[sandreas]

I'm using Slint on a LicheeRV Nano and would like to turn off the display while playing audio to save battery power.

Slint is 1.14.1, Features are ["backend-linuxkms-noseat", "renderer-software", "compat-1-2"]. Is it possible to control the brightness of a display or turn display off and on in an efficient power saving way?

[tronical]

Sometimes the drivers expose a backlight interface in /sys that you can control, but I’m not sure that there is an otherwise portable interface. I suspect you’re looking at a driver specific solution.

[sandreas]

@tronical
Proably solved - see scpcom/LicheeSG-Nano-Build#19 (comment)

Disable backlight: echo 0 > /sys/class/pwm/pwmchip8/pwm2/enable
Enable backlight: echo 1 > /sys/class/pwm/pwmchip8/pwm2/enable

If the PWM is not initialized yet you can do it with (this is normally done by /etc/init.d/S04backlight):

devmem 0x030010AC 32 0x04 # PINMUX PWM10

echo 2 > /sys/class/pwm/pwmchip8/export

echo 2500 > /sys/class/pwm/pwmchip8/pwm2/duty_cycle
echo 10000 > /sys/class/pwm/pwmchip8/pwm2/period
echo 1 > /sys/class/pwm/pwmchip8/pwm2/enable