View source for Template:RK3399 Linux PWMFan

===Fan speed setting===
The fan uses PWM to automatically adjust the speed. It determines the fan switch and the fan speed according to the current CPU temperature. If the current CPU temperature is not high, the fan will be turned off or rotated at a lower speed (reducing unnecessary environmental noise). ), <br />
If you want the fan to start working immediately, you can use the following command to get the CPU running at high load immediately. This is one way to test if the fan works：<br />
<syntaxhighlight lang="bash">
cpuburn
</syntaxhighlight>
if you want to change the speed regulation behavior of the fan, please modify the following file:<br />
<syntaxhighlight lang="bash">
/usr/bin/fa-fancontrol.sh # Entry, called by the pwm-fan.service service to control the fan in two ways, either by the kernel or by the user space by control the PWM.
/usr/bin/fa-fancontrol-direct.sh # Script to control the fan from user space by control the PWM to control the fan speed, etc. This script is called from the above script.
</syntaxhighlight>
Need to cancel the boot automatically start the fan (such as you need to connect the other PWM device), please enter the following command：<br />
<syntaxhighlight lang="bash">
systemctl stop pwm-fan
systemctl disable pwm-fan
</syntaxhighlight>
Or delete the two files below：<br />
<syntaxhighlight lang="bash">
/etc/systemd/system/pwm-fan.service
/etc/systemd/system/multi-user.target.wants/pwm-fan.service
</syntaxhighlight>