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List:       linux-kernel
Subject:    Re: [PATCH] i8k: Add support for temperature sensor labels
From:       Pali =?ISO-8859-1?Q?Roh=E1r?= <pali.rohar () gmail ! com>
Date:       2014-12-03 9:25:26
Message-ID: 1417598726.14672.6.camel () Pali-Nokia-N900
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On Wed Dec    3 10:09:28 2014 Jean Delvare <jdelvare@suse.de> wrote:
> Hi Guenter,
> 
> On Tue, 02 Dec 2014 06:26:29 -0800, Guenter Roeck wrote:
> > On 12/02/2014 05:23 AM, Jean Delvare wrote:
> > > Ultimately /proc/i8k should be killed altogether and every function
> > > should use the appropriate standard interface. But I don't have any
> > > Dell laptop around so I won't go into that myself.
> > 
> > The only function not covered by hwmon, as far as I can see, is reading
> > the "Fn key" status, whatever that is, and reporting the power status
> > (AC or battery).
> > 
> > The first seems to be covered by the already existing dell drivers in
> > platform/x86. The latter must be covered as well; Linux does
> > display the correct power status on all my Dell laptops.
> 
> How old are they? The i8k driver is ancestral, so I could imagine that
> i8k is the only way to report power status on very old Dell laptop
> models. Or maybe not, I just don't know.
> 

It was also for laptops around year 2000. So maybe yes, those laptops probably do not \
have working acpi power status...

> > Changing the ABI is not supposed to happen, so I am not sure if we can
> > just drop the /proc interface.
> 
> Dropping deprecated interfaces after a transition period is not so
> uncommon. AFAIK the proc interface of i8k is only used by the i8kutils
> user-space package, which FWIW is no longer part of openSUSE.

There are some forks of this package which some users use. And openSUSE is not only \
one linux distribution. E.g. In Ubuntu and Debian i8kutils package is still \
available.

> The dell-laptop and dell-wmi drivers are almost 6 years old, that looks
> like an already very comfortable transition period to me.
> 

dell-laptop is using another Dell SMM interface (this one documented), but it does \
not support temperature and fan control status. It is not acpi driver.

dell-wmi is using acpi/wmi for receiving events (nothing more).

I would like to see i8k driver not integrated into dell-laptop becuase it use totally \
different interface...

Anyway, what does i8k mean? That dell interface is somehow called DELLDIAG, so I do \
not know what i8k means...

> That being said, that's only my opinion and I'm not going to fight for
> this. If the hwmon interface is moved to dell-laptop and i8k is killed,
> I'm happy. If the i8k driver is moved to drivers/hwmon and stripped
> down, I'm happy. But if none of this happens, I don't really care, to
> be honest.
> 

For new laptops Fn key status is not supported by i8k (al least on my E6440) and \
power status is reported by acpi.

So what would be probably better is to split driver into two: One which provides only \
/proc/i8k interface (unchanged) and other one which provides hwmon interface.

Users of new laptops do not need /proc/i8k anymore (only if they use i8kutils), so \
would be able to compile only hwmon...

Anyway, do we need to touch /proc/i8k code? It supports only one (first) temperature \
sensor, one fan control... And i think it is already separated from hwmon code (which \
doing some detection of more sensors, fans, ...), so what about moving hwmon \
interface into separate module? We just need some common code for executing SMM \
function.

> -- 
> Jean Delvare
> SUSE L3 Support

-- 
Pali Rohár
pali.rohar@gmail.com

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