Thermal: thermal zone governor fix

This patch does a cleanup about the thermal zone govenor,
setting and make the following rule.
1. For thermal zone devices that are registered w/o tz->tzp,
   they can use the default thermal governor only.
2. For thermal zone devices w/ governor name specified in
   tz->tzp->governor_name, we will use the default govenor
   if the governor specified is not available at the moment,
   and update tz->governor when the matched governor is registered.

This also fixes a problem that OF registered thermal zones
are running with no governor.

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Acked-by: Javi Merino <javi.merino@arm.com>

1 files changed, 18 insertions, 7 deletions

diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
index 02f57af04e3f..71b0ec0c370d 100644
--- a/drivers/thermal/thermal_core.c
+++ b/drivers/thermal/thermal_core.c
@@ -56,10 +56,15 @@ static LIST_HEAD(thermal_governor_list);
 static DEFINE_MUTEX(thermal_list_lock);
 static DEFINE_MUTEX(thermal_governor_lock);
 
+static struct thermal_governor *def_governor;
+
 static struct thermal_governor *__find_governor(const char *name)
 {
         struct thermal_governor *pos;
 
+        if (!name || !name[0])
+                return def_governor;
+
         list_for_each_entry(pos, &thermal_governor_list, governor_list)
                 if (!strnicmp(name, pos->name, THERMAL_NAME_LENGTH))
                         return pos;
@@ -82,17 +87,23 @@ int thermal_register_governor(struct thermal_governor *governor)
         if (__find_governor(governor->name) == NULL) {
                 err = 0;
                 list_add(&governor->governor_list, &thermal_governor_list);
+                if (!def_governor && !strncmp(governor->name,
+                        DEFAULT_THERMAL_GOVERNOR, THERMAL_NAME_LENGTH))
+                        def_governor = governor;
         }
 
         mutex_lock(&thermal_list_lock);
 
         list_for_each_entry(pos, &thermal_tz_list, node) {
+                /*
+                 * only thermal zones with specified tz->tzp->governor_name
+                 * may run with tz->govenor unset
+                 */
                 if (pos->governor)
                         continue;
-                if (pos->tzp)
-                        name = pos->tzp->governor_name;
-                else
-                        name = DEFAULT_THERMAL_GOVERNOR;
+
+                name = pos->tzp->governor_name;
+
                 if (!strnicmp(name, governor->name, THERMAL_NAME_LENGTH))
                         pos->governor = governor;
         }
@@ -342,8 +353,8 @@ static void monitor_thermal_zone(struct thermal_zone_device *tz)
 static void handle_non_critical_trips(struct thermal_zone_device *tz,
                         int trip, enum thermal_trip_type trip_type)
 {
-        if (tz->governor)
-                tz->governor->throttle(tz, trip);
+        tz->governor ? tz->governor->throttle(tz, trip) :
+                       def_governor->throttle(tz, trip);
 }
 
 static void handle_critical_trips(struct thermal_zone_device *tz,
@@ -1533,7 +1544,7 @@ struct thermal_zone_device *thermal_zone_device_register(const char *type,
         if (tz->tzp)
                 tz->governor = __find_governor(tz->tzp->governor_name);
         else
-                tz->governor = __find_governor(DEFAULT_THERMAL_GOVERNOR);
+                tz->governor = def_governor;
 
         mutex_unlock(&thermal_governor_lock);