[coreboot] PECI temperature in lm-sensors

[Аладышев Константин]

1) Yes, PECI pin in SuperIO is actually configured as PECI pin and is connected to PECI pin on Haswell CPU
2) I don't have secret PECI docs either, so I don't know what else should I do...
3) You're right, I want to configure SuperIO to control fans on motherboard based on CPU temperature.

-----Original Message-----
From: Nico Huber [mailto:nico.h at gmx.de] 
Sent: Monday, January 23, 2017 11:42 PM
To: Аладышев Константин
Cc: coreboot at coreboot.org
Subject: Re: [coreboot] PECI temperature in lm-sensors

On 23.01.2017 15:17, Аладышев Константин wrote:
> Does someone have any experience with enabling PECI monitoring on 
> nuvoton SuperIOs ?
> 
> I'm trying to enable it on board with Haswell+Lynxpoint CPU and  
> NCT6776 SuperIO.
> 
> But all I see in lm-sensors output for now is zero temperature for 
> PECI Agent.

I'd first make sure, that the PECI interface is actually connected to a PECI slave. Do you have evidence that this is the case? It's not unusual to leave it unconnected.

> 
> Does coreboot have any SuperIO chips/Intel CPUs/motherboards, that 
> have this functional enabled? What is usually need to be done to 
> enable PECI monitoring?

FWIW (cf. superio/ite/it8772f and others), you have to program the PECI slave address and the command used to retrieve the temperature readings.
What to program seems to be documented in a secret PECI specification (I could only find a license agreement, WTF?). How to program it, is super i/o specific (see datasheet of your chip).

I wonder though, what are you up to? You only need PECI if you want your super i/o to to something automatically (like fan control) based on the readings. If you only want to read out the temperature, you can also directly ask the processor (MSR 0x19c, IIRC).

Nico