Re: IBM Thinkpad Fan Control (acpi_ibm)

Tobias Roth schrieb:
> With acpi_ibm.ko, I can monitor fan speed, thermal sensors and do
> many other nice things. However, my Thinkpad (a T43p) has an awfully
> noisy fan, that, once the notebook reaches its standard working
> temperature (around 45 deg C), turns on and never stops again. 
> 
> The generally accepted solution his to manually lower the fan speed
> and live with the higher temperatures, which will still be in an
> acceptable range even with slow running fans. The discussion and a
> utility for Windows can be found here [1], and a linux tool is
> described here [2]. 
> 
> Now my question. Since acpi_ibm.ko can already read temperature
> sensors and fan speed, would it be feasable to teach it to control
> fan speed as well? Is anyone working on it already? Or can someone
> outline the steps that have to be taken so I can take a look and  
> see if I can do it myself?

I didn't see any practical value in setting fancontrol and fanspeed last
year (that was the time when the T43 wasn't yet around), therefore I
didn't implement write support to prevent users from footshooting.

Now that there is a real practical use of it, I have implemented the
missing bits.

>From the new part of the manpage:


dev.acpi_ibm.0.fan
   Indicates whether the fan is in automatic (1) or manual (0) mode.

dev.acpi_ibm.0.fan_level
   Indicates at what speed the fan should run when being in manual
   mode.  Values are ranging from 0 (off) to 7 (max).  The resulting
   speed differs from model to model.  On a T41p this is as follows:

         0           off
         1, 2        ~3000 RPM
         3, 4, 5     ~3600 RPM
         6, 7        ~4300 RPM

Please try the patch at
http://people.freebsd.org/~markus/ibm/acpi_ibm.c.diff

It should apply cleanly on -CURRENT and 6.0 and works nicely on my T41p.

DISCLAIMER: Use this at your own risk. Messing around with fan speeds
can seriously damage your notebook.

Best regards,

Markus
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