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

Bjorn Helgaas
2007-01-15T17:06:20Z

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?

> So the fan
> driver is unable to turn the fan on, because it thinks that it is
> already in that state.

I suppose the fan driver could use force_power_state to work
around this BIOS bug.

> 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.

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.

Bjorn