Re: hwmon (nct6775): Please fix Invalid temperature source error for NCT6798D

[Guenter Roeck <linux@roeck-us.net>]

On 7/14/20 4:17 PM, Alexey Galakhov wrote:
> Hi,
> 
> I'm facing the same problem. I did some research on my machine.
> 
> On Fri, 2020-07-03 at 10:10 -0700, Guenter Roeck wrote:
> 
>> There is nothing much if anything we can do about that. The NCT6798D
>> datasheet reports temperature source 28 as reserved. You could ask
>> Asus for support, but their usual response is that they don't support
>> Linux.
> 
> Looks like there are different versions of the datasheet. The one of
> NCT6796D, Revision 0.6 states that 28 (0x1c or 11100) is "Select PECI

We are talking about NCT6798D here.

> Agent 0 Calibration as CPUFAN monitoring source." This seems to be correct
> since the fan in question is the CPU one and the value of "PECI Agent 0
> Calibration" is actually very similar to the CPU temperature and rises
> with CPU load.
> 
> Also, looking at the driver code I found no signs of reading so-called
> "HM Read-Only Registers". They are described in section 9.481 of the
> above datasheet. They are I/O ports (readable with `inb`) with their
> base address located in configuration registers 0x64 and 0x65 of the
> SuperIO. Some temperatures seem to be directly readable only through
> these registers. Looks like the driver monitors all temperatures only
> indirectly via switchable channels, is it true?
> 
I have no idea how to access the "HM Read-Only" registers. The datasheets
are not exactly verbal about it.

Guenter