hwmon: (tmp421) report /PVLD condition as fault

stable inclusion
from stable-5.10.71
commit 89d96f147d82c74f8ec1e2812695fbf89ec3e7ee
bugzilla: 182981 https://gitee.com/openeuler/kernel/issues/I4I3KD

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=89d96f147d82c74f8ec1e2812695fbf89ec3e7ee

--------------------------------

[ Upstream commit 540effa7 ]

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: 9410700b ("hwmon: Add driver for Texas Instruments TMP421/422/423 sensor chips")
Signed-off-by: NPaul Fertser <fercerpav@gmail.com>
Link: https://lore.kernel.org/r/20210924093011.26083-2-fercerpav@gmail.comSigned-off-by: NGuenter Roeck <linux@roeck-us.net>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Acked-by: NWeilong Chen <chenweilong@huawei.com>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

drivers/hwmon/tmp421.c

@@ -179,10 +179,10 @@ 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;
@@ -195,9 +195,6 @@ 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: