[PATCH AUTOSEL 6.1 27/53] hwmon: (nct6775) Fix fan speed set failure in automatic mode

[Sasha Levin <sashal@kernel.org>]

From: Xing Tong Wu <xingtong.wu@siemens.com>

[ Upstream commit 8b3800256abad20e91c2698607f9b28591407b19 ]

Setting the fan speed is only valid in manual mode; it is not possible
to set the fan's speed in automatic mode.
Return error when attempting to set the fan speed in automatic mode.

Signed-off-by: Xing Tong Wu <xingtong.wu@siemens.com>
Link: https://lore.kernel.org/r/20231121081604.2499-3-xingtong_wu@163.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/hwmon/nct6775-core.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/hwmon/nct6775-core.c b/drivers/hwmon/nct6775-core.c
index 80310845fb99..9720ad214c20 100644
--- a/drivers/hwmon/nct6775-core.c
+++ b/drivers/hwmon/nct6775-core.c
@@ -2462,6 +2462,13 @@ store_pwm(struct device *dev, struct device_attribute *attr, const char *buf,
 	int err;
 	u16 reg;
 
+	/*
+	 * The fan control mode should be set to manual if the user wants to adjust
+	 * the fan speed. Otherwise, it will fail to set.
+	 */
+	if (index == 0 && data->pwm_enable[nr] > manual)
+		return -EBUSY;
+
 	err = kstrtoul(buf, 10, &val);
 	if (err < 0)
 		return err;
-- 
2.43.0