hwmon: (emc2305) fix pwm never being able to set lower

There are fields 'last_hwmon_state' and 'last_thermal_state' in the
structure 'emc2305_cdev_data', which respectively store the cooling state
set by the 'hwmon' and 'thermal' subsystem, and the driver author hopes
that if the state set by 'hwmon' is lower than the value set by 'thermal',
the driver will just save it without actually setting the pwm. Currently,
the 'last_thermal_state' also be updated by 'hwmon', which will cause the
cooling state to never be set to a lower value. This patch fixes that.

Signed-off-by: Xingjiang Qiao <nanpuyue@gmail.com>
Link: https://lore.kernel.org/r/20221206055331.170459-2-nanpuyue@gmail.com
Fixes: 0d8400c5a2 ("hwmon: (emc2305) add support for EMC2301/2/3/5 RPM-based PWM Fan Speed Controller.")
[groeck: renamed emc2305_set_cur_state_shim -> __emc2305_set_cur_state]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

drivers/hwmon/emc2305.c

@@ -171,22 +171,12 @@ static int emc2305_get_max_state(struct thermal_cooling_device *cdev, unsigned l
 	return 0;
 }
 
-static int emc2305_set_cur_state(struct thermal_cooling_device *cdev, unsigned long state)
+static int __emc2305_set_cur_state(struct emc2305_data *data, int cdev_idx, unsigned long state)
 {
-	int cdev_idx, ret;
-	struct emc2305_data *data = cdev->devdata;
+	int ret;
 	struct i2c_client *client = data->client;
 	u8 val, i;
 
-	if (state > data->max_state)
-		return -EINVAL;
-
-	cdev_idx =  emc2305_get_cdev_idx(cdev);
-	if (cdev_idx < 0)
-		return cdev_idx;
-
-	/* Save thermal state. */
-	data->cdev_data[cdev_idx].last_thermal_state = state;
 	state = max_t(unsigned long, state, data->cdev_data[cdev_idx].last_hwmon_state);
 
 	val = EMC2305_PWM_STATE2DUTY(state, data->max_state, EMC2305_FAN_MAX);
@@ -211,6 +201,27 @@ static int emc2305_set_cur_state(struct thermal_cooling_device *cdev, unsigned l
 	return 0;
 }
 
+static int emc2305_set_cur_state(struct thermal_cooling_device *cdev, unsigned long state)
+{
+	int cdev_idx, ret;
+	struct emc2305_data *data = cdev->devdata;
+
+	if (state > data->max_state)
+		return -EINVAL;
+
+	cdev_idx =  emc2305_get_cdev_idx(cdev);
+	if (cdev_idx < 0)
+		return cdev_idx;
+
+	/* Save thermal state. */
+	data->cdev_data[cdev_idx].last_thermal_state = state;
+	ret = __emc2305_set_cur_state(data, cdev_idx, state);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
 static const struct thermal_cooling_device_ops emc2305_cooling_ops = {
 	.get_max_state = emc2305_get_max_state,
 	.get_cur_state = emc2305_get_cur_state,
@@ -401,7 +412,7 @@ emc2305_write(struct device *dev, enum hwmon_sensor_types type, u32 attr, int ch
 				 */
 				if (data->cdev_data[cdev_idx].last_hwmon_state >=
 				    data->cdev_data[cdev_idx].last_thermal_state)
-					return emc2305_set_cur_state(data->cdev_data[cdev_idx].cdev,
+					return __emc2305_set_cur_state(data, cdev_idx,
 							data->cdev_data[cdev_idx].last_hwmon_state);
 				return 0;
 			}