linux-kernel - Re: Hardware running hot and without the fan

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Message-ID: <1320334322.2309.68.camel@groeck-laptop>
Date:	Thu, 3 Nov 2011 08:32:02 -0700
From:	Guenter Roeck <guenter.roeck@...csson.com>
To:	Lars Noodén <lars.nooden@...il.com>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"lm-sensors@...sensors.org" <lm-sensors@...sensors.org>,
	Henrik Rydberg <rydberg@...omail.se>
Subject: Re: Hardware running hot and without the fan

On Thu, 2011-11-03 at 11:19 -0400, Lars Noodén wrote:
> On 11/03/2011 05:06 PM, Guenter Roeck wrote:
> > On Thu, 2011-11-03 at 10:25 -0400, Lars Noodén wrote:
> [snip]
> >> The one machine reports one fan and the other two fans.  I haven't found
> >> a way to set the fan speed manually.  The output from sensors
> >> is
> >>  https://bugs.launchpad.net/ubuntu/+source/linux/+bug/881593/comments/44
> >> and here
> >>  https://bugs.launchpad.net/ubuntu/+source/linux/+bug/881593/comments/47
> > 
> > Do the fans actually turn, or is the output bogus ?
> 
> The output is bogus, the fans are not turning.  On #47 there above, I
> think the temperatures might be inaccurate, too.  Since they'll go up
> and down as much as 8 degrees in a few seconds.
> 
Maybe 2000 really reflects 0. Not sure about the temperatures - I think
especially the CPU temperature can change pretty fast. Or maybe the
sensors are just not very accurate.

> > You should be able to set the fan speed by writing into the fanX_input
> > and/or fanX_output sysfs attributes. You find those
> > in /sys/class/hwmon/hwmon0/device (assuming there is only one hwmon
> > device).
> 
> I can set the fan speed manually.  e.g.:
> 
>  echo 3500 > /sys/class/hwmon/hwmon0/device/fan1_output
> 
> That helps some.
> 
If you can do that, you should be able to set up fancontrol to
automatically control fan speed based on system temperatures.

There is another sysfs attribute - fanX_manual. I don't find driver
documentation, so I have no idea what it is doing. The name indicates
that it might set manual vs. automatic fan control. What is it set to in
your system ? From the code, looks like it should be 0 or 1. Try to
toggle it and see what happens - after all, it can not get worse ;).

Guenter


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