Commit 9e33c1db authored by Carl Lee's avatar Carl Lee Committed by Guenter Roeck
Browse files

hwmon: (pmbus/mpq8785) fix VOUT_MODE mismatch during identification 



When MPQ8785 reports VOUT_MODE as VID mode, mpq8785_identify()
configures the driver for direct mode. The subsequent
pmbus_identify_common() check then fails due to a mismatch
between the reported mode and the configured mode, causing
device initialization to fail.

Override the reported VOUT_MODE to direct mode to keep the
driver configuration consistent with the reported mode and
allow successful device initialization.

This does not change how voltages are interpreted, but avoids
a false identification failure caused by mismatched mode
handling.

Fixes: f20b4a93 ("hwmon: Add driver for MPS MPQ8785 Synchronous Step-Down Converter")
Signed-off-by: default avatarCarl Lee <carl.lee@amd.com>
Link: https://lore.kernel.org/r/20260210-dt-bindings-hwmon-pmbus-mpq8785-add-mpq8786-support-v3-1-84636ccfe76f@amd.com


Signed-off-by: default avatarGuenter Roeck <linux@roeck-us.net>
parent 8bde3e39

drivers/hwmon/pmbus/mpq8785.c

+28 −0
Original line number Diff line number Diff line
@@ -47,6 +47,33 @@ static int mpq8785_identify(struct i2c_client *client, 
	return 0;

};



static int mpq8785_read_byte_data(struct i2c_client *client, int page, int reg)

{

	int ret;



	switch (reg) {

	case PMBUS_VOUT_MODE:

		ret = pmbus_read_byte_data(client, page, reg);

		if (ret < 0)

			return ret;



		if ((ret >> 5) == 1) {

			/*

			 * The MPQ8785 chip reports VOUT_MODE as VID mode, but the driver

			 * treats VID as direct mode. Without this, identification would fail

			 * due to mode mismatch.

			 * This override ensures the reported mode matches the driver

			 * configuration, allowing successful initialization.

			 */

			return PB_VOUT_MODE_DIRECT;

		}



		return ret;

	default:

		return -ENODATA;

	}

}



static int mpm82504_read_word_data(struct i2c_client *client, int page,

				   int phase, int reg)

{
@@ -129,6 +156,7 @@ static int mpq8785_probe(struct i2c_client *client) 
		break;

	case mpq8785:

		info->identify = mpq8785_identify;

		info->read_byte_data = mpq8785_read_byte_data;

		break;

	default:

		return -ENODEV;