Re: PROBLEM: CPU fan shuts down on load of fan.ko in kernel 2.6.18 and later

Matthew Brett
2007-01-16T00:39:49Z

Hi,

On 1/15/07, Bjorn Helgaas <bjorn.helgaas@hp.com> wrote:
> On Monday 15 January 2007 06:33, Karasyov, Konstantin A wrote:
> > The fan device FAN1 defines object FN01 as its power resource. _STA
> > method of FN01 always return 0x01, i.e. resource is on
>
> Ugh. Matthew, have you checked to see whether there are any
> BIOS updates available for your box?

Ah - my machine is so ill-supported that I was afraid to try any
what-seemed-to-be-appropriate bios updates.

> > But, _ON and _OFF methods set \_TZ.THRM.FNON object to 1 and 0
> > respectively, so, I think, it could be used as value returned by _STA
> > method. Attached patch for DSDT should solve the fan issue.

For reference, it does solve the fan issue - fan stays on during boot,
echo 0 and 3 to /proc/acpi/fan/*/state cause the fan to switch on and
off respectively.

> But we can't expect users to apply DSDT patches. So if there's
> no BIOS update available, don't we have to figure out a way to
> work around it? Maybe we could notice when the BIOS reports the
> device is "on" even when we've turned it off, decide that the
> BIOS is lying, and always use force_power_state.

>From a position of extreme ignorance, a workaround does sound safer -
it's such a dangerous problem,

Best,

Matthew