thermal: sysfs: Rework the handling of trip point updates

Both trip_point_temp_store() and trip_point_hyst_store() use
thermal_zone_set_trip() to update a given trip point, but none of them
actually needs to change more than one field in struct thermal_trip
representing it.  However, each of them effectively calls
__thermal_zone_get_trip() twice in a row for the same trip index value,
once directly and once via thermal_zone_set_trip(), which is not
particularly efficient, and the way in which thermal_zone_set_trip()
carries out the update is not particularly straightforward.

Moreover, input processing need not be done under the thermal zone lock
in any of these functions.

Rework trip_point_temp_store() and trip_point_hyst_store() to address
the above, move the part of thermal_zone_set_trip() that is still
useful to a new function called thermal_zone_trip_updated() and drop
the rest of it.

While at it, make trip_point_hyst_store() reject negative hysteresis
values.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Daniel Lezcano <daniel.lezcano@linaro.org>

1 files changed, 36 insertions, 16 deletions

diff --git a/drivers/thermal/thermal_sysfs.c b/drivers/thermal/thermal_sysfs.c
index eef40d4f3063..06202aa50060 100644
--- a/drivers/thermal/thermal_sysfs.c
+++ b/drivers/thermal/thermal_sysfs.c
@@ -120,8 +120,13 @@ trip_point_temp_store(struct device *dev, struct device_attribute *attr,
 		      const char *buf, size_t count)
 {
 	struct thermal_zone_device *tz = to_thermal_zone(dev);
-	struct thermal_trip trip;
+	struct thermal_trip *trip;
 	int trip_id, ret;
+	int temp;
+
+	ret = kstrtoint(buf, 10, &temp);
+	if (ret)
+		return -EINVAL;
 
 	if (sscanf(attr->attr.name, "trip_point_%d_temp", &trip_id) != 1)
 		return -EINVAL;
@@ -133,15 +138,20 @@ trip_point_temp_store(struct device *dev, struct device_attribute *attr,
 		goto unlock;
 	}
 
-	ret = __thermal_zone_get_trip(tz, trip_id, &trip);
-	if (ret)
-		goto unlock;
+	trip = &tz->trips[trip_id];
 
-	ret = kstrtoint(buf, 10, &trip.temperature);
-	if (ret)
-		goto unlock;
+	if (temp != trip->temperature) {
+		if (tz->ops->set_trip_temp) {
+			ret = tz->ops->set_trip_temp(tz, trip_id, temp);
+			if (ret)
+				goto unlock;
+		}
+
+		trip->temperature = temp;
+
+		thermal_zone_trip_updated(tz, trip);
+	}
 
-	ret = thermal_zone_set_trip(tz, trip_id, &trip);
 unlock:
 	mutex_unlock(&tz->lock);
 	
@@ -179,8 +189,13 @@ trip_point_hyst_store(struct device *dev, struct device_attribute *attr,
 		      const char *buf, size_t count)
 {
 	struct thermal_zone_device *tz = to_thermal_zone(dev);
-	struct thermal_trip trip;
+	struct thermal_trip *trip;
 	int trip_id, ret;
+	int hyst;
+
+	ret = kstrtoint(buf, 10, &hyst);
+	if (ret || hyst < 0)
+		return -EINVAL;
 
 	if (sscanf(attr->attr.name, "trip_point_%d_hyst", &trip_id) != 1)
 		return -EINVAL;
@@ -192,15 +207,20 @@ trip_point_hyst_store(struct device *dev, struct device_attribute *attr,
 		goto unlock;
 	}
 
-	ret = __thermal_zone_get_trip(tz, trip_id, &trip);
-	if (ret)
-		goto unlock;
+	trip = &tz->trips[trip_id];
 
-	ret = kstrtoint(buf, 10, &trip.hysteresis);
-	if (ret)
-		goto unlock;
+	if (hyst != trip->hysteresis) {
+		if (tz->ops->set_trip_hyst) {
+			ret = tz->ops->set_trip_hyst(tz, trip_id, hyst);
+			if (ret)
+				goto unlock;
+		}
+
+		trip->hysteresis = hyst;
+
+		thermal_zone_trip_updated(tz, trip);
+	}
 
-	ret = thermal_zone_set_trip(tz, trip_id, &trip);
 unlock:
 	mutex_unlock(&tz->lock);