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From:   Xing Tong Wu <xingtong_wu@163.com>
To:     Guenter Roeck <linux@roeck-us.net>,
        Jean Delvare <jdelvare@suse.com>, linux-hwmon@vger.kernel.org,
        linux-kernel@vger.kernel.org
Cc:     xingtong.wu@siemens.com, tobias.schaffner@siemens.com,
        gerd.haeussler.ext@siemens.com
Subject: [PATCH v3 2/2] hwmon: (nct6775) Fix fan speed set failure in automatic mode
Date:   Tue, 21 Nov 2023 16:16:04 +0800
Message-Id: <20231121081604.2499-3-xingtong_wu@163.com>
In-Reply-To: <20231121081604.2499-1-xingtong_wu@163.com>
References: <20231121081604.2499-1-xingtong_wu@163.com>
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From: Xing Tong Wu <xingtong.wu@siemens.com>

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>
---
 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 88300fb99bb9..83f1da5acd22 100644
--- a/drivers/hwmon/nct6775-core.c
+++ b/drivers/hwmon/nct6775-core.c
@@ -2553,6 +2553,13 @@ 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;
-- 
2.25.1