From a1ffd3c46267ee5c807acd780e15df9bb692223f Mon Sep 17 00:00:00 2001
From: Vadim Pasternak <vadimp@nvidia.com>
Date: Sun, 12 Feb 2023 16:57:30 +0200
Subject: [PATCH] hwmon: (mlxreg-fan) Return zero speed for broken fan
Git-commit: a1ffd3c46267ee5c807acd780e15df9bb692223f
Patch-mainline: v6.3-rc1
References: git-fixes
Currently for broken fan driver returns value calculated based on error
code (0xFF) in related fan speed register.
Thus, for such fan user gets fan{n}_fault to 1 and fan{n}_input with
misleading value.
Add check for fan fault prior return speed value and return zero if
fault is detected.
Fixes: 65afb4c8e7e4 ("hwmon: (mlxreg-fan) Add support for Mellanox FAN driver")
Signed-off-by: Vadim Pasternak <vadimp@nvidia.com>
Link: https://lore.kernel.org/r/20230212145730.24247-1-vadimp@nvidia.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
drivers/hwmon/mlxreg-fan.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/hwmon/mlxreg-fan.c b/drivers/hwmon/mlxreg-fan.c
index b48bd7c961d6..96017cc8da7e 100644
--- a/drivers/hwmon/mlxreg-fan.c
+++ b/drivers/hwmon/mlxreg-fan.c
@@ -155,6 +155,12 @@ mlxreg_fan_read(struct device *dev, enum hwmon_sensor_types type, u32 attr,
if (err)
return err;
+ if (MLXREG_FAN_GET_FAULT(regval, tacho->mask)) {
+ /* FAN is broken - return zero for FAN speed. */
+ *val = 0;
+ return 0;
+ }
+
*val = MLXREG_FAN_GET_RPM(regval, fan->divider,
fan->samples);
break;
--
2.35.3