copying /sys causes fans to spin up

Olof Johansson olof at
Tue Feb 28 08:33:19 EST 2006

On Tue, Feb 28, 2006 at 08:29:55AM +1100, Benjamin Herrenschmidt wrote:
> On Mon, 2006-02-27 at 17:09 +0100, Olaf Hering wrote:
> > Ben, 
> > 
> > 
> > some tool copies /sys, and while doing it, the fans start to spin up on
> > my G5. Any idea how to fix it, other than not reading from /sys? Have to
> > find the exact file.
> Interesting... it's causing the i2c bus to go nuts... It would be useful
> to find out what file indeed...

For me it's /sys/devices/system/windfarm.0/hd-temp

It also seems that the windfarm module misdetects my system. From dmesg:

PowerMac G5 Thermal control driver 1.2b2
Detected fan controls:
  0: PWM fan, id 1, location: BACKSIDE,SYS CTRLR FAN
  1: RPM fan, id 2, location: DRIVE BAY
  2: PWM fan, id 2, location: SLOT,PCI FAN
  3: RPM fan, id 3, location: CPU A INTAKE
  4: RPM fan, id 4, location: CPU A EXHAUST
  5: RPM fan, id 5, location: CPU B INTAKE
  6: RPM fan, id 6, location: CPU B EXHAUST
  7: RPM fan, id 1, location: CPU A PUMP
  8: RPM fan, id 0, location: CPU B PUMP
PowerMac i2c bus pmu 2 registered
PowerMac i2c bus pmu 1 registered
PowerMac i2c bus mac-io 0 registered
PowerMac i2c bus u3 1 registered
Liquid cooling pumps detected, using new algorithm !
windfarm: failed to attach ds1775 hd-temp to i2c

And it for sure is not a liquid cooled model, the 2.0's never were.

I think this is a 2.6.16-rc2 with the cpufreq patches, but I seems to
have lost the source tree to verify for sure.


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