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From:   Corentin Labbe <clabbe@baylibre.com>
To:     wsa@kernel.org, jdelvare@suse.de
Cc:     linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org,
        Corentin Labbe <clabbe@baylibre.com>
Subject: [PATCH v2] i2c: smbus: add DDR support for SPD
Date:   Mon, 14 Nov 2022 11:56:06 +0000
Message-Id: <20221114115606.1967080-1-clabbe@baylibre.com>
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On my x05 laptop I got:
Memory type 0x12 not supported yet, not instantiating SPD

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

And then, I decoded it successfully via decode-dimms.

Signed-off-by: Corentin Labbe <clabbe@baylibre.com>
---
Changes since v1:
- Added memory type document link
- Added case for LPDDR

 drivers/i2c/i2c-smbus.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/i2c/i2c-smbus.c b/drivers/i2c/i2c-smbus.c
index 07c92c8495a3..c85710ed9548 100644
--- a/drivers/i2c/i2c-smbus.c
+++ b/drivers/i2c/i2c-smbus.c
@@ -361,9 +361,15 @@ void i2c_register_spd(struct i2c_adapter *adap)
 		return;
 	}
 
+	/*
+	 * Memory types could be found at section 7.18.2 (Memory Device — Type), table 78
+	 * https://www.dmtf.org/sites/default/files/standards/documents/DSP0134_3.6.0.pdf
+	 */
 	switch (common_mem_type) {
+	case 0x12:	/* DDR */
 	case 0x13:	/* DDR2 */
 	case 0x18:	/* DDR3 */
+	case 0x1B:	/* LPDDR */
 	case 0x1C:	/* LPDDR2 */
 	case 0x1D:	/* LPDDR3 */
 		name = "spd";
-- 
2.37.4