I run Debian on a ThinkPad T420s. ThinkPad’s have a great Linux compatibility story, and the T420s is no exception. The cooling fan situation seemed in need of some attention though, with fans running at high RPM most of the time. Not only was this really noisy, hit the battery quite hard too.

Enter thinkfan, a simple fan control program.

Works with any linux hwmon driver, especially with thinkpad_acpi. It is designed to eat as little CPU power as possible.

Added bonus, its available in the Debian package repositories.

$ sudo apt-get install thinkfan

Take it for a test drive:

$ sudo thinkfan -n

Two issues. Could not detect the default sensors usually available on a ThinkPad. No ability to actually control the fans (i.e. the thinkpad_acpi kernel modules’ fan_control=1 mode needs to be set).

Kudos to a guy called Jonas on the Ubuntu Forums for sharing his experience getting thinkfan going on his T420, which was aparently sourced from a German post in the ThinkPad wiki. I needed to change a couple of minor things to get it playing nicely with my T420s.

Step 1: Install the thinkfan package.

Step 2: Add kernel module coretemp to /etc/modules

Step 3: Load kernel module coretemp

Step 4: Add the following sensor entries to /etc/thinkfan.conf just before the temperature levels:

Step 5: Create new file /etc/modprobe.d/thinkfan.conf, with the following contents:

options thinkpad_acpi fan_control=1

Step 6: Reload kernel module thinkpad_acpi (i.e. modprobe -r thinkpad_acpi && modprobe thinkpad_acpi)

Step 7: Set START="yes" in /etc/default/thinkfan

Step 8: Start thinkfan /etc/init.d/thinkfan start

Step 9: Verify it works: cat /proc/acpi/ibm/fan. If level has a value between 0 and 7, and changes by times, your thinkfan daemon works.


sensor /sys/devices/platform/coretemp.0/temp1_input
sensor /sys/devices/platform/coretemp.0/temp2_input
sensor /sys/devices/platform/coretemp.0/temp3_input
sensor /sys/devices/virtual/hwmon/hwmon0/temp1_input

(0,     0,      55)
(1,     48,     60)
(2,     50,     61)
(3,     52,     63)
(4,     56,     65)
(5,     59,     66)
(7,     63,     32767)


Useful for getting a feel for what sort of temperature your ThinkPad likes to operate at, and possibly tuning the /etc/thinkfan.conf configuration matrix.

{% highlight bash %} #!/bin/bash

while [ 1 ] do ct1=$(cat /sys/devices/platform/coretemp.0/temp1_input); ct2=$(cat /sys/devices/platform/coretemp.0/temp2_input); ct3=$(cat /sys/devices/platform/coretemp.0/temp3_input); hwmont1=$(cat /sys/devices/virtual/hwmon/hwmon0/temp1_input); echo $ct1 $ct2 $ct3 $hwmont1; sleep 5; done {% endhighlight %}