[RFC v2 9/9] thermal: core: Stop polling DISABLED thermal devices

[Andrzej Pietrasiewicz <andrzej.p@xxxxxxxxxxxxx>]

Polling DISABLED devices is not desired, as all such "disabled" devices
are meant to be handled by userspace.

Add a new mode: THERMAL_DEVICE_INITIAL. It is dedicated to handle devices
which must be initially DISABLED, but which are polled at startup
nonetheless. THERMAL_DEVICE_INITIAL shall be reported as "enabled" in
sysfs to keep the userspace interface intact.

Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@xxxxxxxxxxxxx>
---
 drivers/thermal/thermal_core.c  | 18 ++++++++++++++++--
 drivers/thermal/thermal_sysfs.c |  4 ++--
 include/linux/thermal.h         |  1 +
 3 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
index 7637ddb79813..c3c966a5a50b 100644
--- a/drivers/thermal/thermal_core.c
+++ b/drivers/thermal/thermal_core.c
@@ -305,13 +305,22 @@ 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_get_mode(tz) == THERMAL_DEVICE_DISABLED;
+}
+
 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);
@@ -490,6 +499,9 @@ void thermal_zone_device_update(struct thermal_zone_device *tz,
 {
 	int count;
 
+	if (should_stop_polling(tz))
+		return;
+
 	if (atomic_read(&in_suspend))
 		return;
 
@@ -1356,6 +1368,8 @@ thermal_zone_device_register(const char *type, int trips, int mask,
 	list_add_tail(&tz->node, &thermal_tz_list);
 	mutex_unlock(&thermal_list_lock);
 
+	tz->mode = THERMAL_DEVICE_INITIAL;
+
 	/* Bind cooling devices for this zone */
 	bind_tz(tz);
 
diff --git a/drivers/thermal/thermal_sysfs.c b/drivers/thermal/thermal_sysfs.c
index bc34d0f9768b..9d26196735bd 100644
--- a/drivers/thermal/thermal_sysfs.c
+++ b/drivers/thermal/thermal_sysfs.c
@@ -53,8 +53,8 @@ mode_show(struct device *dev, struct device_attribute *attr, char *buf)
 
 	mode = thermal_zone_device_get_mode(tz);
 
-	return sprintf(buf, "%s\n", mode == THERMAL_DEVICE_ENABLED ? "enabled"
-		       : "disabled");
+	return sprintf(buf, "%s\n", mode == THERMAL_DEVICE_DISABLED ? "disabled"
+		       : "enabled");
 }
 
 static ssize_t
diff --git a/include/linux/thermal.h b/include/linux/thermal.h
index efb481088035..2f61f461da50 100644
--- a/include/linux/thermal.h
+++ b/include/linux/thermal.h
@@ -50,6 +50,7 @@ struct thermal_instance;
 enum thermal_device_mode {
 	THERMAL_DEVICE_DISABLED = 0,
 	THERMAL_DEVICE_ENABLED,
+	THERMAL_DEVICE_INITIAL,
 };
 
 enum thermal_trip_type {
-- 
2.17.1