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#1 2013-03-03 20:09:06

duke11235
Member
Registered: 2009-10-09
Posts: 221

Fan Control

I wanted to ask anyone if they know how the fans are typically controlled in linux. Either before I updated to systemd or before the 2.6.30 kernel, the fans ran normally, but now they are annoyingly loud under no load. lm_sensors detects this

coretemp-isa-0000
Adapter: ISA adapter
Physical id 0:  +55.0°C  (high = +87.0°C, crit = +105.0°C)
Core 0:         +48.0°C  (high = +87.0°C, crit = +105.0°C)
Core 1:         +49.0°C  (high = +87.0°C, crit = +105.0°C)
Core 2:         +47.0°C  (high = +87.0°C, crit = +105.0°C)
Core 3:         +54.0°C  (high = +87.0°C, crit = +105.0°C)

acpitz-virtual-0
Adapter: Virtual device
temp1:        +47.8°C  (crit = +153.8°C)

In addition, I don't see a fan readout in sensors, so I think that I can not use pwmconfig to set the values. I'm running Arch Linux x86_64 on a Clevo P150EM laptop, with AMD7970m and intel 400 graphics and an i7.

Which looks totally reasonable to me, so the only thing I can think of is that there was some change to the fan controller recently. Does anyone have any idea in this regard? I think ACPI deals with the fan, but other than that I have no idea what to do. Can anyone provide any sort of hint?  Thanks

Last edited by duke11235 (2013-03-03 20:16:30)

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#2 2013-03-04 00:41:07

lagagnon
Member
From: an Island in the Pacific...
Registered: 2009-12-10
Posts: 1,077
Website

Re: Fan Control

Not all motherboards are supported for fan control by lm sensors- did you read this:?
https://wiki.archlinux.org/index.php/Fan_Speed_Control


Philosophy is looking for a black cat in a dark room. Metaphysics is looking for a black cat in a dark room that isn't there. Religion is looking for a black cat in a dark room that isn't there and shouting "I found it!". Science is looking for a black cat in a dark room with a flashlight.

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#3 2013-03-04 01:12:17

duke11235
Member
Registered: 2009-10-09
Posts: 221

Re: Fan Control

I know, but I was wondering what would be controlling it if lm_sensors is not. ACPI? the BIOS?

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#4 2013-03-04 01:34:27

ill
Member
From: US
Registered: 2011-06-22
Posts: 115

Re: Fan Control

A lot of motherboards handle controlling them.

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#5 2013-03-04 09:12:17

mich41
Member
Registered: 2012-06-22
Posts: 601

Re: Fan Control

On desktop motherboards, fans are simply controlled by SuperIO chips which are configured by BIOS during boot and can be reconfigured later (but usually are left alone by OS-es).

IDK how exactly it's handled on recent laptops, but AFAIK it could be one of: EC firmware ("Embedded Controller"), SMM code ("System Management Mode" of the CPU), ACPI (a BIOS-provided code executed by OS) or some crazy interaction between them.


Do you have modules thermal and fan loaded? I've heard about laptops which didn't spin up fans without proper ACPI support in the OS.

Last edited by mich41 (2013-03-04 09:13:50)

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