Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Tue, 8 Nov 2022 11:48:51 +0100
From:   Jean Delvare <jdelvare@suse.de>
To:     Corentin Labbe <clabbe@baylibre.com>
Cc:     wsa@kernel.org, linux-i2c@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] i2c: smbus: support new RAM variant for SPD
Message-ID: <20221108114851.4436c3cb@endymion.delvare>
In-Reply-To: <20221107160602.1912225-1-clabbe@baylibre.com>
References: <20221107160602.1912225-1-clabbe@baylibre.com>
Organization: SUSE Linux
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: quoted-printable
Precedence: bulk

Hi Corentin,

On Mon,  7 Nov 2022 16:06:02 +0000, Corentin Labbe wrote:
> On my x05 laptop I got:
> Memory type 0x12 not supported yet, not instantiating SPD


Oh, that one must be old.

> Adding the 0x12 case lead to a successful instantiated SPD AT24 EEPROM.
> i801_smbus 0000:00:1f.3: SMBus using polling
> i2c i2c-6: 2/2 memory slots populated (from DMI)
> at24 6-0050: 256 byte spd EEPROM, read-only
> i2c i2c-6: Successfully instantiated SPD at 0x50
> at24 6-0051: 256 byte spd EEPROM, read-only
> i2c i2c-6: Successfully instantiated SPD at 0x51
>=20
> And then, I decoded it successfully via decode-dimms.
>=20
> Signed-off-by: Corentin Labbe <clabbe@baylibre.com>
> ---
> The result of decode-dimms could be found at http://kernel.montjoie.ovh/z=
oo/x05/decode-dimms.txt
> Since RAM is DDR, I wanted to add '/* DDR */' comment, but I didnt find a=
ny document with
> proof that this 0x12 is for DDR.

It is. The document you are looking for is:
https://www.dmtf.org/sites/default/files/standards/documents/DSP0134_3.6.0.=
pdf

and specifically section 7.18.2 (Memory Device =E2=80=94 Type), table 78
(Memory Device: Type).

>=20
>  drivers/i2c/i2c-smbus.c | 1 +
>  1 file changed, 1 insertion(+)
>=20
> diff --git a/drivers/i2c/i2c-smbus.c b/drivers/i2c/i2c-smbus.c
> index 07c92c8495a3..6dca19c994db 100644
> --- a/drivers/i2c/i2c-smbus.c
> +++ b/drivers/i2c/i2c-smbus.c
> @@ -362,6 +362,7 @@ void i2c_register_spd(struct i2c_adapter *adap)
>  	}
> =20
>  	switch (common_mem_type) {
> +	case 0x12:
>  	case 0x13:	/* DDR2 */
>  	case 0x18:	/* DDR3 */
>  	case 0x1C:	/* LPDDR2 */

Please also add LPDDR (0x1B) for consistency.

Thanks,
--=20
Jean Delvare
SUSE L3 Support