linux-kernel - [PATCH] hwmon: (pmbus_core) Check adapter PEC support

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Date:   Fri,  4 Jun 2021 15:57:14 +0200
From:   Paul Menzel <pmenzel@...gen.mpg.de>
To:     Guenter Roeck <linux@...ck-us.net>,
        Jean Delvare <jdelvare@...e.com>
Cc:     Madhava Reddy Siddareddygari <msiddare@...co.com>,
        Paul Menzel <pmenzel@...gen.mpg.de>,
        linux-hwmon@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] hwmon: (pmbus_core) Check adapter PEC support

From: Madhava Reddy Siddareddygari <msiddare@...co.com>

Currently, for Packet Error Checking (PEC) only the controller
is checked for support. This causes problems on the cisco-8000
platform where a SMBUS transaction errors are observed. This is
because PEC has to be enabled only if both controller and
adapter support it.

Added code to check PEC capability for adapter and enable it
only if both controller and adapter supports PEC.

Signed-off-by: Madhava Reddy Siddareddygari <msiddare@...co.com>
[Upstream from SONiC https://github.com/Azure/sonic-linux-kernel/pull/215]
Signed-off-by: Paul Menzel <pmenzel@...gen.mpg.de>
---
 drivers/hwmon/pmbus/pmbus_core.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c
index bbd745178147..7fbd82b7560d 100644
--- a/drivers/hwmon/pmbus/pmbus_core.c
+++ b/drivers/hwmon/pmbus/pmbus_core.c
@@ -2214,11 +2214,13 @@ static int pmbus_init_common(struct i2c_client *client, struct pmbus_data *data,
 		data->has_status_word = true;
 	}
 
-	/* Enable PEC if the controller supports it */
-	if (!(data->flags & PMBUS_NO_CAPABILITY)) {
-		ret = i2c_smbus_read_byte_data(client, PMBUS_CAPABILITY);
-		if (ret >= 0 && (ret & PB_CAPABILITY_ERROR_CHECK))
+	/* Enable PEC if the controller and bus supports it */
+	ret = i2c_smbus_read_byte_data(client, PMBUS_CAPABILITY);
+	if (ret >= 0 && (ret & PB_CAPABILITY_ERROR_CHECK)) {
+		if (i2c_check_functionality(client->adapter,
+			I2C_FUNC_SMBUS_PEC)) {
 			client->flags |= I2C_CLIENT_PEC;
+		}
 	}
 
 	/*
-- 
2.32.0.rc2