since I'm currently change my rockpro64 setup I came across this.
With the kernel from ayufan you need to set PWM_CTL to/sys/devices/platform/pwm-fan/hwmon/hwmon3/pwm1
for my self compiled one I need/sys/devices/platform/pwm-fan/hwmon/hwmon0/pwm1
But I got it only working with one entry for PWM_CTL e.g.PWM_CTL = "/sys/devices/platform/pwm-fan/hwmon/hwmon0/pwm1",
after that you need to start ats againsudo systemctl stop ats sudo systemctl start ats
initially the fan should start immediately for a short period of time.
In case it is even a different one on your kernel you can find the right one using this command.sudo find /sys -name pwm1 | grep hwmon
So far I'm not sure which kernel parameter or modul changes this.