linux-kernel - Re: [PATCH v4 5/6] i2c: smbus: Support DDR5 SPD EEPROMs

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Date: Wed, 5 Jun 2024 14:21:50 +0200
From: Paul Menzel <pmenzel@...gen.mpg.de>
To: Guenter Roeck <linux@...ck-us.net>
Cc: linux-hwmon@...r.kernel.org, linux-i2c@...r.kernel.org,
 linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
 Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Wolfram Sang <wsa+renesas@...g-engineering.com>,
 René Rebe <rene@...ctcode.de>,
 Thomas Weißschuh <linux@...ssschuh.net>,
 Armin Wolf <W_Armin@....de>, Stephen Horvath <s.horvath@...look.com.au>
Subject: Re: [PATCH v4 5/6] i2c: smbus: Support DDR5 SPD EEPROMs

Dear Guenter,


Thank you so much for taking this on.

Am 04.06.24 um 06:02 schrieb Guenter Roeck:
> Detect DDR5 memory and instantiate the SPD5118 driver automatically.
> 
> Suggested-by: Thomas Weißschuh <linux@...ssschuh.net>
> Cc: Wolfram Sang <wsa+renesas@...g-engineering.com>
> Signed-off-by: Guenter Roeck <linux@...ck-us.net>
> ---
> v5: New patch
> 
>   drivers/i2c/i2c-smbus.c | 4 ++++
>   1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/i2c/i2c-smbus.c b/drivers/i2c/i2c-smbus.c
> index 97f338b123b1..8a0dab835761 100644
> --- a/drivers/i2c/i2c-smbus.c
> +++ b/drivers/i2c/i2c-smbus.c
> @@ -382,6 +382,10 @@ void i2c_register_spd(struct i2c_adapter *adap)
>   	case 0x1E:	/* LPDDR4 */
>   		name = "ee1004";
>   		break;
> +	case 0x22:	/* DDR5 */
> +	case 0x23:	/* LPDDR5 */
> +		name = "spd5118";
> +		break;
>   	default:
>   		dev_info(&adap->dev,
>   			 "Memory type 0x%02x not supported yet, not instantiating SPD\n",

Testing this on top of 6.10-rc2+ on a Supermicro X13SAE, Linux logs:

     $ dmesg | grep -e "DMI:" -e "Linux version" -e i2c-0
     [    0.000000] Linux version 
6.10.0-rc2.mx64.461-00036-g151dfab265df 
(pmenzel@...everalone.molgen.mpg.de) (gcc (GCC) 12.3.0, GNU ld (GNU 
Binutils) 2.41) #74 SMP PREEMPT_DYNAMIC Wed Jun  5 08:24:59 CEST 2024
     [    0.000000] DMI: Supermicro Super Server/X13SAE, BIOS 2.0 10/17/2022
     [    0.000000] DMI: Memory slots populated: 4/4
     [    5.434488] i2c i2c-0: Successfully instantiated SPD at 0x50
     [    5.443848] i2c i2c-0: Successfully instantiated SPD at 0x51
     [    5.450033] i2c i2c-0: Successfully instantiated SPD at 0x52
     [    5.459378] i2c i2c-0: Successfully instantiated SPD at 0x53

Then with `sudo modprobe at24` and `sudo modprobe ee1004`, 
`decode-dimms` shows:

     $ sudo ./eeprom/decode-dimms
     # decode-dimms version 4.3

     Memory Serial Presence Detect Decoder
     By Philip Edelbrock, Christian Zuckschwerdt, Burkart Lingner,
     Jean Delvare, Trent Piepho and others


     Number of SDRAM DIMMs detected and decoded: 0

This might be expected, and `decode-dimms` also needs to be updated.


Kind regards and thank you again for these patches,

Paul