hwmon: (adt7411) set bit 3 in CFG1 register

commit b53893aa upstream.

According to the datasheet you should only write 1 to this bit. If it is
not set, at least AIN3 will return bad values on newer silicon revisions.

Fixes: d84ca5b3 ("hwmon: Add driver for ADT7411 voltage and temperature sensor")
Signed-off-by: Michael Walle <michael@walle.cc>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

drivers/hwmon/adt7411.c

@@ -30,6 +30,7 @@
 
 #define ADT7411_REG_CFG1			0x18
 #define ADT7411_CFG1_START_MONITOR		(1 << 0)
+#define ADT7411_CFG1_RESERVED_BIT3		(1 << 3)
 
 #define ADT7411_REG_CFG2			0x19
 #define ADT7411_CFG2_DISABLE_AVG		(1 << 5)
@@ -292,8 +293,10 @@ static int adt7411_probe(struct i2c_client *client,
 	mutex_init(&data->device_lock);
 	mutex_init(&data->update_lock);
 
+	/* According to the datasheet, we must only write 1 to bit 3 */
 	ret = adt7411_modify_bit(client, ADT7411_REG_CFG1,
-				 ADT7411_CFG1_START_MONITOR, 1);
+				 ADT7411_CFG1_RESERVED_BIT3
+				 | ADT7411_CFG1_START_MONITOR, 1);
 	if (ret < 0)
 		return ret;