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nuumio/99-fan.rules

Created June 21, 2020 06:29
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RK3399 "direct PWM" fan control
Raw
99-fan.rules
# FILE:/etc/udev/rules.d/99-fan.rules
KERNEL=="ff420010.pwm", ACTION=="add", PROGRAM="/usr/local/sbin/fan-control.sh"
Raw
fan-control.sh
#!/bin/bash
# FILE:/usr/local/sbin/fan-control.sh
# Default PWM chip if not set (in udev rules for example)
PWMCHIP="${PWMCHIP:-pwmchip0}"
# Period of 55000 is about 18.2kHz
P=55000
# Few duty cycles that don't cause annoying resonance in my setup
#D=27000
#D=25600
D=23850
#D=22000
#D=21500
#D=20600
#D=18800
cd /sys/class/pwm/${PWMCHIP} && echo 0 > export && cd pwm0/ && echo $P > period && echo $D > duty_cycle && echo 1 > enable
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