linux-kernel - [PATCH v2] i2c: smbus: Add (LP)DDR5 types to `i2c_register

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Date: Sat, 27 Apr 2024 00:07:48 +0200
From: Paul Menzel <pmenzel@...gen.mpg.de>
To: Wolfram Sang <wsa+renesas@...g-engineering.com>
Cc: Paul Menzel <pmenzel@...gen.mpg.de>,
	Jean Delvare <jdelvare@...e.de>,
	linux-i2c@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v2] i2c: smbus: Add (LP)DDR5 types to `i2c_register_spd()`

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].

The same name *ee1004* as for DDR4 is used.

Successfully tested on Supermicro Super Server/X13SAE, BIOS 2.0 10/17/2022:

    [    5.459383] i801_smbus 0000:00:1f.4: SPD Write Disable is set
    [    5.465180] i801_smbus 0000:00:1f.4: SMBus using PCI interrupt
    [    5.465803] intel_pstate: HWP enabled by BIOS
    [    5.474046] i2c i2c-0: Successfully instantiated SPD at 0x50
    [    5.475379] intel_pstate: Intel P-state driver initializing
    [    5.487129] i2c i2c-0: Successfully instantiated SPD at 0x51
    [    5.487350] intel_pstate: HWP enabled
    [    5.493288] i2c i2c-0: Successfully instantiated SPD at 0x52
    [    5.496481] hid: raw HID events driver (C) Jiri Kosina
    [    5.502695] i2c i2c-0: Successfully instantiated SPD at 0x53

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

Signed-off-by: Paul Menzel <pmenzel@...gen.mpg.de>
Cc: Jean Delvare <jdelvare@...e.de>
---
1.  I have no idea if the name ee1004 is correct.
2.  Should I test other things besides looking at the Linux messages?

 drivers/i2c/i2c-smbus.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/i2c/i2c-smbus.c b/drivers/i2c/i2c-smbus.c
index 97f338b123b1..0d67a95c0599 100644
--- a/drivers/i2c/i2c-smbus.c
+++ b/drivers/i2c/i2c-smbus.c
@@ -308,7 +308,7 @@ EXPORT_SYMBOL_GPL(i2c_free_slave_host_notify_device);
  * target systems are the same.
  * Restrictions to automatic SPD instantiation:
  *  - Only works if all filled slots have the same memory type
- *  - Only works for DDR, DDR2, DDR3 and DDR4 for now
+ *  - Only works for DDR, DDR2, DDR3, DDR4 and DDR5 for now
  *  - Only works on systems with 1 to 8 memory slots
  */
 #if IS_ENABLED(CONFIG_DMI)
@@ -380,6 +380,8 @@ void i2c_register_spd(struct i2c_adapter *adap)
 		break;
 	case 0x1A:	/* DDR4 */
 	case 0x1E:	/* LPDDR4 */
+	case 0x22:	/* DDR5 */
+	case 0x23:	/* LPDDR5 */
 		name = "ee1004";
 		break;
 	default:
-- 
2.43.0