How to control fan speed

2008-05-07T08:30:44Z

Acheong87: /* Using a stock kernel */

This page discusses methods for controlling the system fan.

==For Linux==
===Using a patched kernel===
{{NOTE|The ibm-acpi driver is part of the Linux kernel 2.6.10 and later (option CONFIG_ACPI_IBM), so patching is not needed anymore.}}
{{WARN|This patch is superceded by the patches in [[ibm-acpi]] [[Git]] repository or [http://ibm-acpi.sourceforge.net ibm-acpi.sf.net] releases}}
{{NOTE|Advanced fan control through ibm-acpi has been merged in Linux 2.6.20-rc2 mainline, so users of 2.6.20 won't need to patch their kernels to get the '''fan level''' functionality anymore}}

The [[Patch for controlling fan speed]] provides a convenient interface via {{path|/proc/acpi/ibm/fan}}.

Manual speed control can be done through the [[patch for controlling fan speed]]:

'''#cat /proc/acpi/ibm/fan'''
status: enabled
level: auto
speed: 4219
commands: enable, disable, level <level>
(<level> is 0-7, auto or disengaged)

'''#echo level 2 > /proc/acpi/ibm/fan'''

'''#cat /proc/acpi/ibm/fan'''
status: enabled
level: 2
speed: 3142
commands: enable, disable, level <level>
(<level> is 0-7, auto or disengaged)

===Using a stock kernel===

{{NOTE|Fan control operations are disabled by default for safety reasons.}}

'''Linux Kernel 2.6.22 and Above (ibm-acpi has been replaced by [[thinkpad-acpi]])'''

To enable fan control, the module parameter <tt>fan_control=1</tt> must be given to thinkpad-acpi.

For example, in Ubuntu 8.04 (Hardy Heron), add the following to {{path|/etc/modprobe.d/options}}: <tt>options thinkpad_acpi fan_control=1</tt>

Having done so, use the following commands to control fan speed:

{{cmdroot|echo level 0 > /proc/acpi/ibm/fan}} (fan off)

{{cmdroot|echo level 2 > /proc/acpi/ibm/fan}} (low speed)

{{cmdroot|echo level 4 > /proc/acpi/ibm/fan}} (medium speed)

{{cmdroot|echo level 7 > /proc/acpi/ibm/fan}} (maximum speed)

{{cmdroot|echo level auto > /proc/acpi/ibm/fan}} (automatic - default)

{{cmdroot|echo level disengaged > /proc/acpi/ibm/fan}} (disengaged)

'''Older Linux Kernels (using [[ibm-acpi]])'''

To enable fan control, the module parameter <tt>experimental=1</tt> must be given to ibm-acpi. Then, you can control the fan by directly writing to the relevant embedded controller register, {{path|/proc/acpi/ibm/ecdump}}.

For example:

{{cmdroot|echo 0x2F 0x00 > /proc/acpi/ibm/ecdump}} (fan off)

{{cmdroot|echo 0x2F 0x02 > /proc/acpi/ibm/ecdump}} (low speed)

{{cmdroot|echo 0x2F 0x04 > /proc/acpi/ibm/ecdump}} (medium speed)

{{cmdroot|echo 0x2F 0x07 > /proc/acpi/ibm/ecdump}} (maximum speed)

{{cmdroot|echo 0x2F 0x80 > /proc/acpi/ibm/ecdump}} (automatic - default)

{{cmdroot|echo 0x2F 0x40 > /proc/acpi/ibm/ecdump}} (disengaged)

See the specifications below for the meaning of these modes.

===On/off control using stock kernel===

If you only wish to turn the fan on and off (with automatic control when it's on), you can use the following.

When loading [[ibm-acpi]] v0.11 with experimental switch ({{cmdroot|1=modprobe ibm_acpi experimental=1}}), it is possible to read and write the status of fan:

'''#cat /proc/acpi/ibm/fan'''
status: enabled
speed: 3580
commands: enable, disable

'''#echo disable > /proc/acpi/ibm/fan'''

'''cat /proc/acpi/ibm/fan'''
status: disabled
speed: 0
commands: enable, disable

When off, the fan will then '''never''' wake up. It is advised to use an automated control script to reduce the chance of hardware damage.

===Automated control scripts===

An [[ACPI fan control script#Variable speed control scripts|ACPI fan control script]] can be used to override the firmware's fan algorithm with gentler, quieter version. It monitors the laptop's [[thermal sensors]] and sets the fan speed accordingly, according to customizable thresholds. For the default behavior, simply save {{CodeRef|tp-fancontrol}} as {{path|tp-fancontrol}}, make sure you've loaded [[thinkpad-acpi]] with the "fan_control=1" parameter, and run:<br />
{{cmdroot|./tp-fancontrol}}

There is an distro independent daemon (http://projekte.f4.fhtw-berlin.de/trac/s0332819-linuxtools/wiki/), written in python. Packages are available for debian based linux systems.

[http://www.gambitchess.org/moin.py/ThinkPad_Fan_Control A GTK GUI program (packaged for Ubuntu 7.10 and 8.04)] may also help.

==For Windows==

Shimodax's ThinkPad fan control tool offers similar functionality (see [http://forum.thinkpads.com/viewtopic.php?t=17715 forum discussion] at thinkpads.com). Source and binaries are available through the [http://sourceforge.net/projects/tp4xfancontrol "Tp4xFanControl"] project on SourceForge.

==Hardware specs==

The following hardware behavior was discovered experimentally by [[User:Thinker|Thinker]] and neither provided by nor confirmed by IBM/Lenovo. The following description may be inaccurate and may vary by model (see list of models above). The terminology probably does not match the one used by IBM/Lenovo engineers.

{{NOTE|Information on other models is included in the [[ibm-acpi]] [[Git]] version.}}
{{NOTE|1=The ThinkPad {{X61s}} and {{X61}} with WWAN have a [http://forum.notebookreview.com/showthread.php?t=141931 second system fan]; its interface is currently unknown.}}

ACPI DSDT register HFSP (8 bits, offset 0x2F in the <tt>EmbeddedController</tt> address space, accessed through the standard EC interface at IO ports 0x62 and 0x66) is read/writable and has the following meaning:

Bits 7 6 5 4 3 2 1 0
---------------
Value 1 0 * * * * * * - automatic
* 1 * * * * * * - disengaged
0 0 N N N N N N - manual (0..63; 0=disable fan, 1=min, ..., 7=max)

Changing modes may not be immediate on all ThinkPads. Later ThinkPad models seem to take at least 5s to start responding to a fan mode change, for example.

After boot, the HFSP register may not reflect the true state of the EC (on some models it reads 0x07 even though the EC is actually in automatic mode).

=== Fan Tachometer ===

The embedded controller registers 0x84 (LSB), 0x85 (MSB) are the main fan tachometer, and report fan speed in RPM in everything since the {{A31}} and maybe a little earlier. Not much is know about the tachometer in earlier models, or even whether they had one or not.

=== Automatic mode ===
In ''automatic'' mode, the embedded controller sets the fan speed automatically according to system temperatures and some unknown algorithm.

Note that the ACPI DSDT may supplement this in some models. The {{X40}}, for example, changes the profile of speeds the automatic mode should use depending on battery status.

=== Manual mode ===

In ''manual'' mode, the fan level is forced to the given value and the EC will auto-regulate the fan to maintain at a (roughly) constant RPM, which is model-dependent. Manual speed levels 8-63 yield the same behavior as level 7, and the the ACPI DSDT uses level 7 for the emergency mode it enters upon critical CPU/GPU temperature, so apparently 7 is the real maximum level.

=== Disengaged (full-speed) mode ===

In ''disengaged'' mode, the embedded controller does not monitor the fan speed. It "disengages" the closed-loop control function that keeps track of fan speed, and uses an open-loop control function that ramps up the fan to its maximum speed (100% duty-cycle). The end speed is not stable, but it is often much faster than the maximum speed manual and automatic modes would set the fan to.

Most newer ThinkPads take quite a while (in excess of one minute) to fully enter disengaged mode. Exiting it is much faster. The {{A31}} acts differently, and switches to disengaged mode as fast as it switches to other modes.

For some reason, the embedded controller may stop updating the tachometer registers while entering or exiting disengaged mode in some ThinkPad firmware versions (hence the EC tachometer registers will not be updated on these models while entering/exiting disengaged mode). Once it arrives at maximum speed, or once it gets back at closed-loop cruise speed, the embedded controller starts updating the tachometer registers again. Later T models such as the {{T43}} have this problem, while the {{A31}} does not.

{{HINT|Apparently the [[Problem with fan noise|pulsing fan noise]] experienced by some users can be cured by repeatedly running 2-4 seconds of manual control followed by 0.5-1 seconds of disengaged mode. The pulse occurs when the the embedded controller computes the fan speed and adjusts the fan voltage adaptively every few seconds (~4.8sec for the ThinkPad T43); the aforementioned mode switching doesn't give it a chance to do so. One of the [[ACPI fan control script#Variable speed control scripts|ACPI fan control scripts]] implements this solution.}}

==Supported models==

The above was successfully tested on the following models:

* ThinkPad {{A31}} (fan levels RPM: 0 = off, 1-2 = ~3280-3380 (!), 3-5 = ~3200, 6-7 = ~3380, "disengaged" = ~4000 (see NOTE above))
* ThinkPad {{R50}} (highest manual level is 3; disengage mode works and reaches much higher RPM)
* ThinkPad {{R50p}} (fan levels RPM: 0 = off, 1-2 = ~3200, 3-5 = ~3500-3600, 6-7 = ~3700-3800, disengaged = ~5300)
* ThinkPad {{R51}} (fan levels RPM: 0 = off, 1-2 = ~3150, 3-5 = ~3350, 6 = ~3750, disengaged = ~5100)
* ThinkPad {{R51e}} (fan levels RPM: 0 = off, 1-2 = ~3300, 3-5 = ~3800, 6 = ~4150, disengaged = ~5100)
* ThinkPad {{R52}} (fan levels RPM: 0 = off, 1-2 = ~3350, 3-5 = ~3650, 6 = ~4250, disengaged = ~5245)
* ThinkPad {{R60}} (fan levels RPM: 0 = off, 1-1 = ~2650, 3-5 = ~3300, 6-7 = ~3950, disengaged = ~4800)
* ThinkPad {{R60e}}
* ThinkPad {{T22}}
* ThinkPad {{T23}} (low speed = ~2200, medium and maximum speed = ~4800; disengaged mode works at ~5800)
* ThinkPad {{T30}}
* ThinkPad {{T40}} (fan levels RPM: 1-2 = ~2950, 3-5 = ~3600, 6-7 = ~4050; disengaged = ~5400)
* ThinkPad {{T41}}, {{T41p}} (fan levels RPM: 1-2 = ~2980, 3-5 = ~3500, 6-7 = ~4050; disengaged mode works at ~5100)
* ThinkPad {{T42}}, {{T42p}} (fan levels RPM: 1-2 = ~2900, 3-5 = ~3700, 6-7 = ~4700; disengaged mode works at ~5200)
* ThinkPad {{T43}}, {{T43p}} (fan levels RPM: 1-2 = ~3300, 3-5 = ~4100, 6-7 = ~4700; disengaged mode works at ~6450)
* ThinkPad {{T60}} (fan levels RPM: 1-2 = 3000-3100, 3-5 = ~3600, 6-7 = ~4500; disengaged mode works at ~5500)
* ThinkPad {{T61}} (fan levels RPM: 0 = off, 1-2 = ~2980, 3-5 = ~3330, 6-7 = ~3760; disengaged mode works at ~4500)
* ThinkPad {{X30}} (level 0 = off, low = ~3900, medium = ~4200, maximum = ~4650, disengaged = ~5900)
* ThinkPad {{X31}} (fan levels RPM: 0 = off, 1-2 = ~2850, 3-5 = ~3450, 6 = ~4050, 7 = ~4150; disengaged mode works at ~4975)
* ThinkPad {{X40}}
* ThinkPad {{X41}}
* ThinkPad {{X41T}}
* ThinkPad {{X60}}
* ThinkPad {{X61s}}
* ThinkPad {{Z60t}}, {{Z60m}} (fan levels RPM: 1-2 = ~1700, 3-5 = ~2800, 6-7 = ~3500)
* ThinkPad {{Z61m}}
* Thinkpad {{Z61p}} (fan levels 0-7, auto, disengaged; enable, disable; watchdog (untested))
Probably other models are supported too (please update this page if you confirm this; maintain some ordering too).

==Models using a different interface==

The following models also work, use a different access method which supported (only) via the {{path|/proc/acpi/ibm/fan}} of [[ibm-acpi]]. No need for patching.

* ThinkPad {{600E}}, {{600X}}, {{770E}}, {{770X}} (these use a different fan control interface)

==Unsupported models==

* ThinkPad {{560}} (these models don't have a fan)

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How to control fan speed