Thermal: Ignore invalid trip points

In some cases, platform thermal driver may report invalid trip points,
thermal core should not take any action for these trip points.

This fixed a regression that bogus trip point starts to screw up thermal
control on some Lenovo laptops, after
commit bb431ba26c
Author: Zhang Rui <rui.zhang@intel.com>
Date:   Fri Oct 30 16:31:47 2015 +0800

    Thermal: initialize thermal zone device correctly

    After thermal zone device registered, as we have not read any
    temperature before, thus tz->temperature should not be 0,
    which actually means 0C, and thermal trend is not available.
    In this case, we need specially handling for the first
    thermal_zone_device_update().

    Both thermal core framework and step_wise governor is
    enhanced to handle this. And since the step_wise governor
    is the only one that uses trends, so it's the only thermal
    governor that needs to be updated.

    Tested-by: Manuel Krause <manuelkrause@netscape.net>
    Tested-by: szegad <szegadlo@poczta.onet.pl>
    Tested-by: prash <prash.n.rao@gmail.com>
    Tested-by: amish <ammdispose-arch@yahoo.com>
    Tested-by: Matthias <morpheusxyz123@yahoo.de>
    Reviewed-by: Javi Merino <javi.merino@arm.com>
    Signed-off-by: Zhang Rui <rui.zhang@intel.com>
    Signed-off-by: Chen Yu <yu.c.chen@intel.com>

CC: <stable@vger.kernel.org> #3.18+
Link: https://bugzilla.redhat.com/show_bug.cgi?id=1317190
Link: https://bugzilla.kernel.org/show_bug.cgi?id=114551
Signed-off-by: Zhang Rui <rui.zhang@intel.com>

drivers/thermal/thermal_core.c

@@ -454,6 +454,10 @@ static void handle_thermal_trip(struct thermal_zone_device *tz, int trip)
 {
 	enum thermal_trip_type type;
 
+	/* Ignore disabled trip points */
+	if (test_bit(trip, &tz->trips_disabled))
+		return;
+
 	tz->ops->get_trip_type(tz, trip, &type);
 
 	if (type == THERMAL_TRIP_CRITICAL || type == THERMAL_TRIP_HOT)
@@ -1800,6 +1804,7 @@ struct thermal_zone_device *thermal_zone_device_register(const char *type,
 {
 	struct thermal_zone_device *tz;
 	enum thermal_trip_type trip_type;
+	int trip_temp;
 	int result;
 	int count;
 	int passive = 0;
@@ -1871,9 +1876,15 @@ struct thermal_zone_device *thermal_zone_device_register(const char *type,
 		goto unregister;
 
 	for (count = 0; count < trips; count++) {
-		tz->ops->get_trip_type(tz, count, &trip_type);
+		if (tz->ops->get_trip_type(tz, count, &trip_type))
+			set_bit(count, &tz->trips_disabled);
 		if (trip_type == THERMAL_TRIP_PASSIVE)
 			passive = 1;
+		if (tz->ops->get_trip_temp(tz, count, &trip_temp))
+			set_bit(count, &tz->trips_disabled);
+		/* Check for bogus trip points */
+		if (trip_temp == 0)
+			set_bit(count, &tz->trips_disabled);
 	}
 
 	if (!passive) {

include/linux/thermal.h

@@ -156,6 +156,7 @@ struct thermal_attr {
  * @trip_hyst_attrs:	attributes for trip points for sysfs: trip hysteresis
  * @devdata:	private pointer for device private data
  * @trips:	number of trip points the thermal zone supports
+ * @trips_disabled;	bitmap for disabled trips
  * @passive_delay:	number of milliseconds to wait between polls when
  *			performing passive cooling.
  * @polling_delay:	number of milliseconds to wait between polls when
@@ -191,6 +192,7 @@ struct thermal_zone_device {
 	struct thermal_attr *trip_hyst_attrs;
 	void *devdata;
 	int trips;
+	unsigned long trips_disabled;	/* bitmap for disabled trips */
 	int passive_delay;
 	int polling_delay;
 	int temperature;