linux-kernel - Re: [PATCH] i2c: smbus: Add (LP)DDR5 types to `i2c_register

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Message-ID: <20240426071022.lqapnn6uzcypezrp@ninjato>
Date: Fri, 26 Apr 2024 09:10:22 +0200
From: Wolfram Sang <wsa+renesas@...g-engineering.com>
To: Paul Menzel <pmenzel@...gen.mpg.de>, Jean Delvare <jdelvare@...e.de>
Cc: linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] i2c: smbus: Add (LP)DDR5 types to `i2c_register_spd()`

Hi Paul,

(adding Jean)

On Wed, Mar 27, 2024 at 09:33:55AM +0100, Paul Menzel wrote:
> On several systems Linux logs:
> 
>      i2c i2c-0: Memory type 0x22 not supported yet, not instantiating SPD
> 
> 1.  Supermicro Super Server/X13SAE, BIOS 2.0 10/17/2022
> 2.  Dell Inc. Precision 3660/0PRR48, BIOS 2.9.3 11/22/2023
> 3.  Dell Inc. OptiPlex SFF Plus 7010/0YGWFV, BIOS 1.7.1 08/11/2023
> 4.  Run `git grep 'emory type.*supported yet, not instantiating SPD'` in
>     the repository of dmesg reports for various computers collected by
>     Linux users at https://linux-hardware.org. [1]
> 
> Add 0x22 and 0x23 for DDR5 according to section 7.18.2 (Memory Device —
> Type), table 78 in *System Management BIOS (SMBIOS) Reference
> Specification*, version 3.6.0 [2].
> 
> I use the same name as for DDR4 out of ignorance.

So, you didn't test it on DDR5 on your own? I'd like to have it tested.
The document you referenced does only mention I2C but the wikipedia
article [3]  mentions I3C. It will probably support I2C fallback, but
I'd like to be sure.

[3] https://en.wikipedia.org/wiki/Serial_presence_detect

> [1]: https://www.dmtf.org/sites/default/files/standards/documents/DSP0134_3.6.0.pdf
> [2]: https://github.com/linuxhw/Dmesg

[1] and [2] are mixed up.

Thanks for the patch!

   Wolfram


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