[lm-sensors] Intel DH55HC Sensors
guenter.roeck at ericsson.com
Mon Mar 19 22:46:03 CET 2012
On Mon, 2012-03-19 at 17:01 -0400, Christopher Head wrote:
> On Wed, 14 Mar 2012 20:36:55 -0700
> Guenter Roeck <guenter.roeck at ericsson.com> wrote:
> > On Wed, Mar 14, 2012 at 05:36:59PM -0400, Christopher Head wrote:
> > > Hi,
> > > I'm trying to get my DH55HC's sensors working. Detection indicates
> > > w83627dhg-isa-0a10 as the device. According to the wiki at
> > > <http://lm-sensors.org/wiki/VoltageLabelsAndScaling>, this chip is
> > > capable of reading 8 mV/LSb. Here's the problem: the division ratio
> > > doesn't make sense! In the BIOS, I observed the following values on
> > > the 12 V rail:
> > >
> > > 11.828
> > > 11.844
> > > 11.859
> > >
> > > The difference between these values is 15 or 16 mV. But 12 V / 0.016
> > > V/LSb = 750 LSb! Since these sensor chips don't read raw values
> > > above 255, how in the world am I getting 16 mV resolution on a 12 V
> > > input? I'm seeing similar results on my 5 V rail, which returns
> > > values just 2 mV apart in the BIOS, and on my so-called "Memory
> > > V_SM" rail (2 mV) and "+Vccp" rail (differences as small as 1 mV
> > > being displayed).
> > >
> > > Any ideas?
> > >
> > The BIOS may get its voltages through HECI, which uses a different
> > set of ADCs built into the H55 PCH.
> > Guenter
> It's possible; I did see a mailing list message (on this list, in the
> archives) explaining that the PCH is used for fan speed reporting on
> this board. Is there any more recent news on PCH support in lm_sensors?
> I don't have a lot of time but if it's a programming problem I may be
> able to give some assistance.
I briefly looked into this a while ago, after the HECI (MEI) driver was
put back into the kernel. Problem is that it is not well documented, and
it is built around the assumption that it would only be used from user
space applications. This means one would need to understand it enough to
1) port the necessary user space libraries into the kernel, 2) modify
the MEI driver to support those in-kernel libraries, and 3) use the
libraries to write a hwmon driver.
Writing the hwmon driver would be straightforward, but the rest is just
too much for my spare time.
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