[lm-sensors] Lack of fan sensor output after Ubuntu upgrade

Jean Delvare khali at linux-fr.org
Sat Sep 11 10:53:39 CEST 2010

On Fri, 10 Sep 2010 09:15:27 -0700, Guenter Roeck wrote:
> On Fri, Sep 10, 2010 at 09:29:25AM -0400, Lars Ivar Igesund wrote:
> > Probing for Super-I/O at 0x4e/0x4f
> > 
> > Trying family `National Semiconductor'... Yes
> > 
> > Found unknown chip with ID 0x8512
> > 
> > Is this something of interest?
> Most likely this is a Nuvoton chip; they use chip id 0x85 for another chip.

This doesn't strike me as a particularly relevant data point.

> Don't recall seeing this specific ID, though, or why it is identified
> as National Semiconductor.

Different vendors use different "access keys" to the LPC configuration
space. These are sequences of bytes to be written to the register port.
National Semiconductor is (was) the only vendor without an access key,
that is, you can access the configuration space at any time. For this
reason, we try to detect National Semiconductor devices first.

Nuvoton indeed has one chip in this family (WPCD377I) because this
device is an older National Semiconductor device they inherited when
buying part of National Semiconductor's business a few years ago. So
the mysterious chip could indeed be a Nuvoton-labelled chip, but be a
National Semiconductor design.

Either way, most LPC chips on laptops are minimalist and don't include
hardware monitoring features, so there's probably little interest in
investigating this. The only way to move forward would be to find a
detailed listing of this laptop's parts (very hard to get usually) or
to open the laptop's case and have a visual look (usually not easy

As in most laptop cases, the problem and solution are more likely
related to laptop-specific code or ACPI.

Jean Delvare

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