How-to start fans during early boot

[ShadowDance]

If you want the fans of your Helios64 to start spinning earlier, look no further. This will allow the fans to spin at a constant speed from the earliest stage of initrd until fancontrol is started by the system. My use-case is for full disk encryption and recovery in initramfs, sometimes I can have the machine powered on for quite a while before fancontrol starts. Or, if the boot process encounters an error the fans may never start, this prevents that.

 

Step 1: Tell initramfs to include the pwm-fan module

echo pwm-fan | sudo tee -a /etc/initramfs-tools/modules

 

Step 2: Create a new file at /etc/initramfs-tools/scripts/init-top/fan with the following contents:

#!/bin/sh

PREREQ=""
prereqs() {
        echo "$PREREQ"
}

case $1 in
prereqs)
        prereqs
        exit 0
        ;;
esac

. /scripts/functions

modprobe pwm-fan

for pwm in /sys/devices/platform/p*-fan/hwmon/hwmon*/pwm1; do
        echo 150 >$pwm
done

exit 0

Feel free to change the value 150 anywhere between 1-255, it decides how fast the fans will spin.

 

Step 3: Enable the fan script for inclusion in initramfs and update the initramfs image:

sudo chmod +x /etc/initramfs-tools/scripts/init-top/fan
sudo update-initramfs -u -k all

 

Step 4: Reboot and ejoy the cool breeze.

[barnumbirr]

This is actually really smart. @gprovost could something along these lines be added to the default setup?

[gprovost]

Nice approach and you right it is something we should implement in baseline. We will work on that.