linux-kernel - [PATCH 02/10] hwmon: (amc6821) Make reading and writing fan speed limits consistent

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Message-Id: <20240628151346.1152838-3-linux@roeck-us.net>
Date: Fri, 28 Jun 2024 08:13:38 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: linux-hwmon@...r.kernel.org
Cc: linux-kernel@...r.kernel.org,
	Farouk Bouabid <farouk.bouabid@...rry.de>,
	Quentin Schulz <quentin.schulz@...rry.de>,
	Guenter Roeck <linux@...ck-us.net>
Subject: [PATCH 02/10] hwmon: (amc6821) Make reading and writing fan speed limits consistent

The default value of the maximum fan speed limit register is 0,
essentially translating to an unlimited fan speed. When reading
the limit, a value of 0 is reported in this case. However, writing
a value of 0 results in writing a value of 0xffff into the register,
which is inconsistent.

Signed-off-by: Guenter Roeck <linux@...ck-us.net>
---
 drivers/hwmon/amc6821.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/hwmon/amc6821.c b/drivers/hwmon/amc6821.c
index 3c614a0bd192..e37257ae1a6b 100644
--- a/drivers/hwmon/amc6821.c
+++ b/drivers/hwmon/amc6821.c
@@ -601,7 +601,7 @@ static ssize_t fan_show(struct device *dev, struct device_attribute *devattr,
 	struct amc6821_data *data = amc6821_update_device(dev);
 	int ix = to_sensor_dev_attr(devattr)->index;
 	if (0 == data->fan[ix])
-		return sprintf(buf, "0");
+		return sprintf(buf, "6000000");
 	return sprintf(buf, "%d\n", (int)(6000000 / data->fan[ix]));
 }
 
@@ -625,10 +625,10 @@ static ssize_t fan_store(struct device *dev, struct device_attribute *attr,
 	int ret = kstrtol(buf, 10, &val);
 	if (ret)
 		return ret;
-	val = 1 > val ? 0xFFFF : 6000000/val;
+	val = val < 1 ? 0xFFFF : 6000000 / val;
 
 	mutex_lock(&data->update_lock);
-	data->fan[ix] = (u16) clamp_val(val, 1, 0xFFFF);
+	data->fan[ix] = (u16)clamp_val(val, 0, 0xFFFF);
 	if (i2c_smbus_write_byte_data(client, fan_reg_low[ix],
 			data->fan[ix] & 0xFF)) {
 		dev_err(&client->dev, "Register write error, aborting.\n");
-- 
2.39.2