linux-kernel - Re: [PATCH 2/3] hwmon: Add support for SPD5118 compliant temperature sensors

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Message-ID: <34a4292e-c4db-4b40-822e-b892e1444045@t-8ch.de>
Date: Thu, 30 May 2024 22:20:37 +0200
From: Thomas Weißschuh <thomas@...ch.de>
To: Guenter Roeck <linux@...ck-us.net>
Cc: linux-hwmon@...r.kernel.org, Hristo Venev <hristo@...ev.name>, 
	René Rebe <rene@...ctcode.de>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Radu Sabau <radu.sabau@...log.com>
Subject: Re: [PATCH 2/3] hwmon: Add support for SPD5118 compliant temperature
 sensors

On 2024-05-29 13:52:03+0000, Guenter Roeck wrote:
> Add support for SPD5118 (Jedec JESD300-5B.01) compliant temperature
> sensors. Such sensors are typically found on DDR5 memory modules.

I can get the module to automatically probe with this change:

diff --git a/drivers/i2c/i2c-smbus.c b/drivers/i2c/i2c-smbus.c
index 97f338b123b1..8d9218f755d7 100644
--- a/drivers/i2c/i2c-smbus.c
+++ b/drivers/i2c/i2c-smbus.c
@@ -382,6 +386,10 @@ 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",

(Credits go to Paul Menzel [0])

Maybe you can add that to your series.

To also work with my PIIX4 I2C bus, I also need:

diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index fe6e8a1bb607..ff66e883b348 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -195,6 +195,7 @@ config I2C_ISMT
 config I2C_PIIX4
        tristate "Intel PIIX4 and compatible (ATI/AMD/Serverworks/Broadcom/SMSC)"
        depends on PCI && HAS_IOPORT
+       select I2C_SMBUS
        help
          If you say yes to this option, support will be included for the Intel
          PIIX4 family of mainboard I2C interfaces.  Specifically, the following
diff --git a/drivers/i2c/busses/i2c-piix4.c b/drivers/i2c/busses/i2c-piix4.c
index 6a0392172b2f..f8d81f8c0cb3 100644
--- a/drivers/i2c/busses/i2c-piix4.c
+++ b/drivers/i2c/busses/i2c-piix4.c
@@ -29,6 +29,7 @@
 #include <linux/stddef.h>
 #include <linux/ioport.h>
 #include <linux/i2c.h>
+#include <linux/i2c-smbus.h>
 #include <linux/slab.h>
 #include <linux/dmi.h>
 #include <linux/acpi.h>
@@ -982,6 +983,8 @@ static int piix4_add_adapter(struct pci_dev *dev, unsigned short smba,
                return retval;
        }

+       i2c_register_spd(adap);
+
        *padap = adap;
        return 0;
 }

Though I guess it's not the right place to call i2c_register_sdp(),
I'll look at it some more and then submit it.

[0] https://lore.kernel.org/lkml/20240530183444.9312-2-pmenzel@molgen.mpg.de/