Configuring PWM sysfs entries

Configuring PWM sysfs entries

[Domenico Andreoli]

Hi,

I'm using fancontrol on a NanoPi M4 having a PWM controlled fan.

This is the configuration I'm using:

INTERVAL=10
FCTEMPS=/sys/class/pwm/pwmchip1/pwm0/duty_cycle=/sys/class/hwmon/hwmon1/temp1_input
MINTEMP=/sys/class/pwm/pwmchip1/pwm0/duty_cycle=45
MAXTEMP=/sys/class/pwm/pwmchip1/pwm0/duty_cycle=70
MINSTART=/sys/class/pwm/pwmchip1/pwm0/duty_cycle=1500000
MINSTOP=/sys/class/pwm/pwmchip1/pwm0/duty_cycle=1500000
MAXPWM=/sys/class/pwm/pwmchip1/pwm0/duty_cycle=10000000

This is effective only after sysfs has been configured:

PWM=0
CHIP=1
POLARITY=normal
PERIOD=10000000

echo $PWM > /sys/class/pwm/pwmchip$CHIP/export
echo $PERIOD > /sys/class/pwm/pwmchip$CHIP/pwm$PWM/period
echo $POLARITY > /sys/class/pwm/pwmchip$CHIP/pwm$PWM/polarity
echo 1 > /sys/class/pwm/pwmchip$CHIP/pwm$PWM/enable

Additional caveat, fancontrol accepts PWM values up to 255 while my
configuration works iff such value is 1500000. Therefore I have to
comment out the max PWM value check in the fancontrol script.

Is this the best way to achieve the result?

Would you accept a patch to improve fancontrol and handle this situation
in a nicer way?

Kind regards,
Domenico

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