thermal: core: Stop polling DISABLED thermal devices

Polling DISABLED devices is not desired, as all such "disabled" devices
are meant to be handled by userspace. This patch introduces and uses
should_stop_polling() to decide whether the device should be polled or not.
Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@collabora.com>
Reviewed-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Reviewed-by: Amit Kucheria <amit.kucheria@linaro.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20200629122925.21729-10-andrzej.p@collabora.com

drivers/thermal/thermal_core.c

@@ -301,13 +301,22 @@ static void thermal_zone_device_set_polling(struct thermal_zone_device *tz,
 		cancel_delayed_work(&tz->poll_queue);
 }
 
+static inline bool should_stop_polling(struct thermal_zone_device *tz)
+{
+	return !thermal_zone_device_is_enabled(tz);
+}
+
 static void monitor_thermal_zone(struct thermal_zone_device *tz)
 {
+	bool stop;
+
+	stop = should_stop_polling(tz);
+
 	mutex_lock(&tz->lock);
 
-	if (tz->passive)
+	if (!stop && tz->passive)
 		thermal_zone_device_set_polling(tz, tz->passive_delay);
-	else if (tz->polling_delay)
+	else if (!stop && tz->polling_delay)
 		thermal_zone_device_set_polling(tz, tz->polling_delay);
 	else
 		thermal_zone_device_set_polling(tz, 0);
@@ -517,6 +526,9 @@ void thermal_zone_device_update(struct thermal_zone_device *tz,
 {
 	int count;
 
+	if (should_stop_polling(tz))
+		return;
+
 	if (atomic_read(&in_suspend))
 		return;