Re: 2.6.10-mm2: it87 sensor driver stops CPU fan

[Nicolas Pitre <nico@cam.org>]

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On Mon, 10 Jan 2005, Jean Delvare wrote:

> When I get this, I'll compare with the datasheets so as to understand
> how your chip is configured (or left unconfigured) by your BIOS. This
> will both help me propose a workaround in the it87 driver and explain
> the Gigabyte support what I think they should do.

FWIW, I have a Gigabyte motherboard with an it87 chip too.  Reading 
about this it87 polarity thing I'm suspecting something is really wrong 
here:

When system is idle, the sensors report shows:
CPU temp = +25°C and CPU fan = 2136 RPM (and rather noisy)

When system is 100% busy (with dd if=/dev/urandom of=/dev/null):
CPU temp = +41°C and CPU fan =   1288 RPM (and obviously much quieter)

I'm running a 2.6.10 kernel (not -mm) so I guess the BIOS settings for 
fan control are not altered.  And incidentally the BIOS has a setting 
called "smart fan control" set to "enabled" which maps to the ITxxF 
automatic PWM control mode I suppose.  So if the BIOS actually set the 
fan polarity wrong then the fan would slow down when the temperature 
rises and vice versa, right?


Nicolas