hwmon: (lm77) Do not preserve hysteresis when updating critical temp limit

Updating the hysteresis value when updating the critical temperature limit
was following the rule of 'least surprise'. However, it had the undesirable
side effect of changing the hysteresis for all other attributes, which
defeats the purpose of least surprise. In addition, it could result in
invalid hysteresis values if the resulting hysteresis was too large. In such
cases the resulting hysteresis ended up changed anyway, which again defeats
the purpose. So drop that code and document the new behavior.

Reviewed-by: Jean Delvare <jdelvare@suse.de>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

1 files changed, 0 insertions, 6 deletions

diff --git a/drivers/hwmon/lm77.c b/drivers/hwmon/lm77.c
index 4cd8a513c47b..85e5b3355be4 100644
--- a/drivers/hwmon/lm77.c
+++ b/drivers/hwmon/lm77.c
@@ -216,13 +216,11 @@ static ssize_t set_temp_crit_hyst(struct device *dev,
 	return count;
 }
 
-/* preserve hysteresis when setting T_crit */
 static ssize_t set_temp_crit(struct device *dev, struct device_attribute *attr,
 			     const char *buf, size_t count)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	struct lm77_data *data = i2c_get_clientdata(client);
-	int oldcrithyst;
 	unsigned long val;
 	int err;
 
@@ -231,13 +229,9 @@ static ssize_t set_temp_crit(struct device *dev, struct device_attribute *attr,
 		return err;
 
 	mutex_lock(&data->update_lock);
-	oldcrithyst = data->temp_crit - data->temp_hyst;
 	data->temp_crit = val;
-	data->temp_hyst = data->temp_crit - oldcrithyst;
 	lm77_write_value(client, LM77_REG_TEMP_CRIT,
 			 LM77_TEMP_TO_REG(data->temp_crit));
-	lm77_write_value(client, LM77_REG_TEMP_HYST,
-			 LM77_TEMP_TO_REG(data->temp_hyst));
 	mutex_unlock(&data->update_lock);
 	return count;
 }