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From:   Paul Fertser <fercerpav@gmail.com>
To:     linux-hwmon@vger.kernel.org
Cc:     Jean Delvare <jdelvare@suse.com>,
        Guenter Roeck <linux@roeck-us.net>,
        linux-kernel@vger.kernel.org, Paul Fertser <fercerpav@gmail.com>
Subject: [PATCH v3 2/3] hwmon: tmp421: report /PVLD condition as fault
Date:   Fri, 24 Sep 2021 12:30:10 +0300
Message-Id: <20210924093011.26083-2-fercerpav@gmail.com>
In-Reply-To: <20210924093011.26083-1-fercerpav@gmail.com>
References: <20210924022020.GA3032273@roeck-us.net>
 <20210924093011.26083-1-fercerpav@gmail.com>
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For both local and remote sensors all the supported ICs can report an
"undervoltage lockout" condition which means the conversion wasn't
properly performed due to insufficient power supply voltage and so the
measurement results can't be trusted.

Fixes: 9410700b881f ("hwmon: Add driver for Texas Instruments TMP421/422/423 sensor chips")
Signed-off-by: Paul Fertser <fercerpav@gmail.com>
---

Changes from v2:
 - Add Fixes: tag

Changes from v1:
 - Trivial rebase

 drivers/hwmon/tmp421.c | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/drivers/hwmon/tmp421.c b/drivers/hwmon/tmp421.c
index e6b2b31d17c8..3a789f21188c 100644
--- a/drivers/hwmon/tmp421.c
+++ b/drivers/hwmon/tmp421.c
@@ -182,10 +182,10 @@ static int tmp421_read(struct device *dev, enum hwmon_sensor_types type,
 		return 0;
 	case hwmon_temp_fault:
 		/*
-		 * The OPEN bit signals a fault. This is bit 0 of the temperature
-		 * register (low byte).
+		 * Any of OPEN or /PVLD bits indicate a hardware mulfunction
+		 * and the conversion result may be incorrect
 		 */
-		*val = tmp421->temp[channel] & 0x01;
+		*val = !!(tmp421->temp[channel] & 0x03);
 		return 0;
 	default:
 		return -EOPNOTSUPP;
@@ -198,9 +198,6 @@ static umode_t tmp421_is_visible(const void *data, enum hwmon_sensor_types type,
 {
 	switch (attr) {
 	case hwmon_temp_fault:
-		if (channel == 0)
-			return 0;
-		return 0444;
 	case hwmon_temp_input:
 		return 0444;
 	default:
-- 
2.17.1