linux-kernel - k10temp: ZEN3 readings are broken

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Date:   Tue, 22 Dec 2020 02:45:02 +0100
From:   Gabriel C <nix.or.die@...glemail.com>
To:     Guenter Roeck <linux@...ck-us.net>
Cc:     linux-hwmon@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
        Wei Huang <wei.huang2@....com>
Subject: k10temp: ZEN3 readings are broken

Hello Guenter,

while trying to add ZEN3 support for zenpower out of tree modules, I find out
the in-kernel k10temp driver is broken with ZEN3 ( and partially ZEN2 even ).

commit 55163a1c00fcb526e2aa9f7f952fb38d3543da5e added:

case 0x0 ... 0x1:       /* Zen3 */

however, this is wrong, we look for a model which is 0x21 for ZEN3,
these seem to
be steppings?

Also, PLANE0/1 are wrong too, Icore has zero readouts even when fixing
the model.

Looking at these ( there is something missing for 0x71 ZEN2 Ryzens
also ) that should be:

PLANE0  (ZEN_SVI_BASE + 0x10)
PLANE1  (ZEN_SVI_BASE + 0xc)

Which is the same as for ZEN2 >= 0x71. Since this is not really
documented and I have some
confirmations of these numbers from *somewhere* :-) I created a demo patch only.

I would like AMD people to really have a look at the driver and
confirm the changes, since
getting information from *somewhere*,  dosen't mean they are 100%
correct. However, the driver
is working with these changes.

In any way the model needs changing to 0x21 even if we let the other
readings broken.

There is my demo patch:

https://crazy.dev.frugalware.org/fix-ZEN2-ZEN3-test1.patch

Also, there is some discuss and testing for both drivers:

https://github.com/ocerman/zenpower/issues/39

Best Regards,

Gabriel C