linux-kernel - Re: Dell Latitude E6440 & i8k

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Date:	Fri, 16 May 2014 21:23:02 +0200
From:	Pali Rohár <pali.rohar@...il.com>
To:	Jean Delvare <jdelvare@...e.de>
Cc:	Guenter Roeck <linux@...ck-us.net>, linux-kernel@...r.kernel.org
Subject: Re: Dell Latitude E6440 & i8k

On Friday 16 May 2014 21:11:17 Jean Delvare wrote:
> Hi Pali,
> 
> On Fri, 16 May 2014 20:37:41 +0200, Pali Rohár wrote:
> > Hello,
> > 
> > on Dell Latitude E6440 driver i8k reporting total nonsense
> > values
> 
> That's kind of excessive wording, the output isn't that bad.
> 

I mean fan RPM & temp4. Those are for sure incorrect.

> > $ sensors
> > i8k-virtual-0
> > Adapter: Virtual device
> > Right Fan:   93450 RPM
> > CPU:          +57.0°C
> > temp2:        +57.0°C
> > temp3:        +40.0°C
> > temp4:       +127.0°C
> > 
> > Right Fan and temp4 are for sure incorrect.
> 
> Driver is reverse-engineered so this is best effort and some
> tweaking may be needed.
> 

Ok, if driver is developed without any documentation, then it 
make sense that not working correctly on new machines...

So is not there any documentation? I think that Dell released 
some SMM/BIOS code... But I'm not sure about it.

> > Value temp4 is always 127 and is never changing, but value
> > for Right Fan is increasing when fan is more noisy. So it
> > looks like value for Right Fan is not correctly normalized
> > or multiplier is incorrect.
> > 
> > And name "Right" is incorrect too. Fan is on left side of
> > this notebook, not right as reported by driver.
> > 
> > It is possible to fix these problems?
> 
> Load the i8k driver with fan_mult=1.
> 

Looks like now it reports more plausible value for fan. When fan 
is at low it reporting between 3000 - 3100 RPM.

> Add the following to /etc/sensors.d/i8k.conf:
> 
> chip "i8k-virtual-0"
> 
>    label fan2 "Left Fan"
>    ignore temp4

And this fixing output from sensors program.

$ sensors
i8k-virtual-0
Adapter: Virtual device
Left Fan:    3088 RPM
CPU:          +54.0°C  
temp2:        +57.0°C  
temp3:        +40.0°C

But Right Fan name is still present in kernel sysfs:

$ grep "" /sys/class/hwmon/hwmon1/*
/sys/class/hwmon/hwmon1/fan2_input:3091
/sys/class/hwmon/hwmon1/fan2_label:Right Fan
/sys/class/hwmon/hwmon1/name:i8k
/sys/class/hwmon/hwmon1/pwm2:128
/sys/class/hwmon/hwmon1/temp1_input:56000
/sys/class/hwmon/hwmon1/temp1_label:CPU
/sys/class/hwmon/hwmon1/temp2_input:57000
/sys/class/hwmon/hwmon1/temp3_input:40000
/sys/class/hwmon/hwmon1/temp4_input:127000

-- 
Pali Rohár
pali.rohar@...il.com

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