hwmon: (w83627ehf) Permit enabling SmartFan IV mode if configured at startup

If SmartFan IV mode was configured at startup, it should be possible
to re-enable it later on.

Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
Acked-by: Ian Dobson <i.dobson@planet-ian.com>

drivers/hwmon/w83627ehf.c

@@ -346,7 +346,10 @@ struct w83627ehf_data {
 			     2->thermal cruise mode (also called SmartFan I)
 			     3->fan speed cruise mode
 			     4->variable thermal cruise (also called
-				SmartFan III) */
+				SmartFan III)
+			     5->enhanced variable thermal cruise (also called
+				SmartFan IV) */
+	u8 pwm_enable_orig[4];	/* original value of pwm_enable */
 	u8 pwm_num;		/* number of pwm */
 	u8 pwm[4];
 	u8 target_temp[4];
@@ -1055,7 +1058,7 @@ store_pwm_enable(struct device *dev, struct device_attribute *attr,
 	if (err < 0)
 		return err;
 
-	if (!val || (val > 4))
+	if (!val || (val > 4 && val != data->pwm_enable_orig[nr]))
 		return -EINVAL;
 	mutex_lock(&data->update_lock);
 	reg = w83627ehf_read_value(data, W83627EHF_REG_PWM_ENABLE[nr]);
@@ -1617,6 +1620,11 @@ static int __devinit w83627ehf_probe(struct platform_device *pdev)
 	/* Read fan clock dividers immediately */
 	w83627ehf_update_fan_div(data);
 
+	/* Read pwm data to save original values */
+	w83627ehf_update_pwm_common(dev, data);
+	for (i = 0; i < data->pwm_num; i++)
+		data->pwm_enable_orig[i] = data->pwm_enable[i];
+
 	/* Register sysfs hooks */
 	for (i = 0; i < ARRAY_SIZE(sda_sf3_arrays); i++) {
 		err = device_create_file(dev, &sda_sf3_arrays[i].dev_attr);