thermal: step_wise: cdev only needs update on a new target state

The cooling device only needs update on a new target state.  Since we
already check old target in thermal_zone_trip_update(), we can do one
more check to see if it's a new target state.  If not, we can reasonably
save some uncecesary code execution.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Acked-by: Eduardo Valentin <eduardo.valentin@ti.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>

diff --git a/drivers/thermal/step_wise.c b/drivers/thermal/step_wise.c
index 4d4ddae..0afbd86 100644 (file)
--- a/drivers/thermal/step_wise.c
+++ b/drivers/thermal/step_wise.c
@@ -133,6 +133,9 @@ static void thermal_zone_trip_update(struct thermal_zone_device *tz, int trip)
                old_target = instance->target;
                instance->target = get_target_state(instance, trend, throttle);
 
+               if (old_target == instance->target)
+                       continue;
+
                /* Activate a passive thermal instance */
                if (old_target == THERMAL_NO_TARGET &&
                        instance->target != THERMAL_NO_TARGET)