linux-kernel - [PATCH v2] hwmon: (pmbus) Clear pmbus fault/warning bits after read

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Date:   Tue, 22 Feb 2022 13:12:53 +0000
From:   Vikash Chandola <vikash.chandola@...ux.intel.com>
To:     linux@...ck-us.net, jdelvare@...e.com, linux-hwmon@...r.kernel.org,
        linux-kernel@...r.kernel.org, iwona.winiarska@...el.com
Cc:     Vikash Chandola <vikash.chandola@...ux.intel.com>
Subject: [PATCH v2] hwmon: (pmbus) Clear pmbus fault/warning bits after read

Almost all fault/warning bits in pmbus status registers remain set even
after fault/warning condition are removed. As per pmbus specification
these faults must be cleared by user.
Modify hwmon behavior to clear fault/warning bit after fetching data if
fault/warning bit was set. This allows to get fresh data in next read.

Signed-off-by: Vikash Chandola <vikash.chandola@...ux.intel.com>
---
changes since v1:
v1 patch was clearing all the faults. That would have lead faults not
getting reported to user at all. This change clears only current fault
and that too after reporting it at least once. This way all the faults
will be reported to user space at least once.

Behaviour has been verified with following PSU
FRU Device Description : IS162F22 (ID 84)
Product Manufacturer   : SOLUM CO., LTD.
Product Name           : IS162F22
Product Part Number    : G36234-015
Product Version        : 10A

 drivers/hwmon/pmbus/pmbus_core.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c
index 776ee2237be2..ac2fbee1ba9c 100644
--- a/drivers/hwmon/pmbus/pmbus_core.c
+++ b/drivers/hwmon/pmbus/pmbus_core.c
@@ -911,6 +911,11 @@ static int pmbus_get_boolean(struct i2c_client *client, struct pmbus_boolean *b,
 		pmbus_update_sensor_data(client, s2);
 
 	regval = status & mask;
+	if (regval) {
+		ret = pmbus_write_byte_data(client, page, reg, regval);
+		if (ret)
+			goto unlock;
+	}
 	if (s1 && s2) {
 		s64 v1, v2;
 
-- 
2.25.1