linux-kernel - Re: k10temp: ZEN3 readings are broken

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Message-ID: <9d621d34-e5ce-301a-1b89-92c0791fe348@roeck-us.net>
Date:   Mon, 21 Dec 2020 19:58:42 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Gabriel C <nix.or.die@...glemail.com>
Cc:     linux-hwmon@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
        Wei Huang <wei.huang2@....com>
Subject: Re: k10temp: ZEN3 readings are broken

Hi,

On 12/21/20 5:45 PM, Gabriel C wrote:
> 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
> 

Thanks for the information. However, since I do not have time to actively maintain
the driver, since each chip variant seems to use different addresses and scales,
and since the information about voltages and currents is unpublished by AMD,
I'll remove support for voltage/current readings from the upstream driver.
I plan to send the patch doing that to Linus shortly after the commit window
closes (or even before that).

Thanks,
Guenter