linux-kernel - Re: Useless thermal acpi driver ?

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Message-id: <alpine.LFD.2.00.0912110122570.24891@localhost.localdomain>
Date:	Fri, 11 Dec 2009 01:25:49 -0500 (EST)
From:	Len Brown <lenb@...nel.org>
To:	Robert Hancock <hancockrwd@...il.com>
Cc:	J.A. Magallón <jamagallon@....com>,
	LKML <linux-kernel@...r.kernel.org>, linux-acpi@...r.kernel.org
Subject: Re: Useless thermal acpi driver ?

On Wed, 9 Dec 2009, Robert Hancock wrote:

> On 12/09/2009 04:26 PM, J.A. Magallón wrote:
> > Hi all...
> > 
> > I have a couple boxes where the thermal acpi driver gives this:
> > 
> > bran:~>  sensors
> > acpitz-virtual-0
> > Adapter: Virtual device
> > temp1:       +26.8°C  (crit = +100.0°C)
> > 
> > bran:~>  acpi -t
> > No support for device type: battery
> >       Thermal 1: ok, 27.0 degrees C
> > 
> > It stays _always_ the same, there is no difference if I run some number
> > crunchin, or even if one of them is overclocked from 2.8 to 3.0 GHz.
> 
> There are systems where an ACPI thermal zone exists but isn't really hooked up
> to anything and just reports some dummy temperature value. My old system
> reported 40 degrees C no matter what. (I think it's something like the thermal
> zone support is part of the standard ACPI DSDT template the mobo maker got
> from the BIOS developer and they effectively disabled it by putting in the
> dummy temperature.)

send the output from acpidump, and a quick look will tell us
if your ACPI suport is dummy, or accesses real registers.

Also, show the output from

grep . /proc/acpi/thermal_zone/*/*

cheers,
-Len Brown, Intel Open Source Technology Center

> > They are 1U supermicro boxes, ventilation is good, but I don't trust this
> > measures...
> > It looks like the system is using some kind of 'generic' acpi TZ driver,
> > but as I'm used to good-ol' sensors modules, I don't know where to look.
> > 
> > Previously I used the w83627hf module from sensors.
> 
> I'm assuming the kernel is preventing that module from loading since the ACPI
> DSDT has operation regions that refer to the device registers. There's no
> guarantee that this means the BIOS actually accesses the device, or if it
> does, that there's a way to get it to report what it sees other than to
> itself. If the BIOS doesn't actually access the device then you can use the
> acpi_enforce_resources=lax to allow it. The problem is this might be totally
> unsafe and the kernel has no way to tell if it is or isn't.
> --
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