Re: [lm-sensors] sensors.conf for DFI LP MI P55-T36 (it8720-*)

[Jean Delvare <khali@linux-fr.org>]

On 25 Jun 2010 08:32:06 -0000, Lars Kr.Lundin wrote:
> On Thu, Jun 24, 2010 at 09:18:20AM +0200, Jean Delvare wrote:
> 
> > > The bottom line is that your chip is properly configured and won't be
> > > affected by the fix I'm working on.
> 
> Many thanks for doing this.
> 
> > >
> > > Also note that you could improve your configuration file by adding the
> > > following:
> > >
> > >    label  in3  "+5V"
> > >    label  in7  "5VSB"
> > >    compute  in3  @ * (6.8/10+1), @ / (6.8/10+1)
> > >    compute  in7  @ * (6.8/10+1), @ / (6.8/10+1)
> 
> Thanks! I have updated my sensors.conf at
> http://www.eso.org/~llundin/sff/sensors.conf
> 
> For in[01256] I assumed that the reported value _is_ the voltage.
> Is this a valid assumption?

Yes it is. The IT8720F uses a 4V ADV, so all voltage lines below 3.5V
can be monitored directly.

> 
> > Oh, and while we're here, in4 is +12V. This is confirmed by this
> > snapshot I've found:
> > http://img19.imageshack.us/img19/6122/dmip55os2.png
> >
> > The only missing thing is the scaling factor. Apparently it's not the
> > standard one, otherwise it would read between +10.48 V and +11.32 V on
> > your system, which is definitely too low.
> >
> > Is +12V really not displayed in the hardware monitoring section of your
> > BIOS? This is very surprising.
> >
> 
> The +12V is displayed in the BIOS, an example readout is 11.776V, see
> http://www.eso.org/~llundin/sff/p1010501_800x600.jpg

Can you please wait a bit in this screen and try to gather other sample
values for +12V? If you can gather 2 or 3 different samples, we may be
able to guess the scaling factor.

> Based on your comments it is now apparent that the voltages displayed in
> the BIOS are reported by sensors in the exact same order. I guess I didn't
> realize this because I didn't know that (some of) the voltages would
> need scaling by sensors.
> 
> In one case `sensors` report in4 as 2.62V. If you have a suggestion for
> how to determine the in4 scaling factor then I will be happy to help.

2.62V in sensors for 11.776V in the BIOS suggests a scaling factor of
about 4.5. For something more accurate, we need more samples from both
the BIOS (see above) and the it87 driver. "sensors" only displays 2
decimal places, so better get the exact reading from sysfs directly:

cat /sys/class/hwmon/hwmon*/device/in4_input

If you can gather 2 or 3 samples of each, finding the scaling factor
should be reasonably easy.

> (I wonder if this could have the slightest relevance, but my board is
> powered by a 200W PW-200-M from MINI-Box).

Wow, this is cute :) Yes, this probably explains why your voltages are
rather below the average.

> > I suppose you don't have Windows running on your machine for comparison
> > with the DFI software?
> 
> No, I did my last Windows installation around 2002. Although I would like
> to help, I cannot say I am sorry about this.

I fully understand :)

> Many thanks again for your interest, help and explanations,
> -Lars Lundin.
> PS. Is there any effort to have LM sensors detect an Nvidia GPU temperature?
> I have a collection of (new and old) low-end Nvidia cards and would be
> happy to help.

We can write the sensor chip drivers (and have done so for many
already: LM63, LM99 etc.) but the I2C access to these chips is the
graphics driver's job. Which are improving over time in this respect,
so it should work someday. I'm not actively working on this though
(probably due to the lack of nVidia card in my systems.)

-- 
Jean Delvare

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