linux-kernel - Re: [PATCH] i8k: Add support for temperature sensor labels

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Message-Id: <201411301844.44562@pali>
Date:	Sun, 30 Nov 2014 18:44:44 +0100
From:	Pali Rohár <pali.rohar@...il.com>
To:	Guenter Roeck <linux@...ck-us.net>
Cc:	Gabriele Mazzotta <gabriele.mzt@...il.com>,
	Arnd Bergmann <arnd@...db.de>,
	"Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
	Steven Honeyman <stevenhoneyman@...il.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] i8k: Add support for temperature sensor labels

On Sunday 30 November 2014 17:00:18 Guenter Roeck wrote:
> On 11/30/2014 01:53 AM, Pali Rohár wrote:
> [ ... ]
> 
> >>> Original Dell DOS executable ignores all temperature
> >>> sensors if type SMM function fails (if I decoded and
> >>> understand that DOS assembler code correctly). So maybe
> >>> we should do same...
> >>> 
> >>> But because our i8k.c code ignores sensor only if it
> >>> returns invalid temperature, there could be possible
> >>> regression that on same machines type SMM function is not
> >>> implemented or not working...
> >>> 
> >>> What do you think?
> >> 
> >> Tested with XPS13, Studio 1555 (with GPU), and XPS M140.
> >> Reading the type works with all of them. The Studio 1555
> >> reports the GPU temperature in temp4. The M140 is quite old
> >> (about 10 years), so I guess we can be reasonably sure that
> >> all laptops currently in use support reporting the type.
> > 
> > Good. Then I will split this patch into two parts. One which
> > adds labels and one which change init code to register only
> > those sensors which have valid type.
> 
> Ok.
> 
> >> Do you know what is returned for the type if the GPU is
> >> turned off on a system with GPU ? I think that is the only
> >> open question.
> > 
> > Yes, on my E6440 in both cases when GPU is turned off and on
> > is returned same type (GPU). So this does not help us.
> 
> Unless I misunderstand you, it does help us; it simplifies
> sensor detection since we don't have to handle the special
> case that the GPU is turned off anymore.
> 
> Thanks,
> Guenter

Yes, sensor type is returned always correctly, so this is good.

I mean that it cannot be used for detecting if GPU is turned on 
or off.

-- 
Pali Rohár
pali.rohar@...il.com

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