OPP: Don't drop opp->np reference while it is still in use

The struct dev_pm_opp contains a reference of the DT node, opp->np,
throughout its lifetime. We should increase the refcount for the same
from _opp_add_static_v2(), and drop it while removing the OPP finally.
Signed-off-by: Liang He <windhl@126.com>
[ Viresh: Updated subject / commit log, create _of_clear_opp() and drop
	  reference from it]
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

drivers/opp/core.c

@@ -1553,7 +1553,7 @@ static void _opp_kref_release(struct kref *kref)
 	 * frequency/voltage list.
 	 */
 	blocking_notifier_call_chain(&opp_table->head, OPP_EVENT_REMOVE, opp);
-	_of_opp_free_required_opps(opp_table, opp);
+	_of_clear_opp(opp_table, opp);
 	opp_debug_remove_one(opp);
 	kfree(opp);
 }

drivers/opp/of.c

@@ -254,8 +254,8 @@ void _of_clear_opp_table(struct opp_table *opp_table)
  * Release all resources previously acquired with a call to
  * _of_opp_alloc_required_opps().
  */
-void _of_opp_free_required_opps(struct opp_table *opp_table,
-				struct dev_pm_opp *opp)
+static void _of_opp_free_required_opps(struct opp_table *opp_table,
+				       struct dev_pm_opp *opp)
 {
 	struct dev_pm_opp **required_opps = opp->required_opps;
 	int i;
@@ -275,6 +275,12 @@ void _of_opp_free_required_opps(struct opp_table *opp_table,
 	kfree(required_opps);
 }
 
+void _of_clear_opp(struct opp_table *opp_table, struct dev_pm_opp *opp)
+{
+	_of_opp_free_required_opps(opp_table, opp);
+	of_node_put(opp->np);
+}
+
 /* Populate all required OPPs which are part of "required-opps" list */
 static int _of_opp_alloc_required_opps(struct opp_table *opp_table,
 				       struct dev_pm_opp *opp)
@@ -938,7 +944,7 @@ static struct dev_pm_opp *_opp_add_static_v2(struct opp_table *opp_table,
 
 	new_opp->turbo = of_property_read_bool(np, "turbo-mode");
 
-	new_opp->np = np;
+	new_opp->np = of_node_get(np);
 	new_opp->dynamic = false;
 	new_opp->available = true;
 

drivers/opp/opp.h

@@ -267,14 +267,12 @@ static inline bool lazy_linking_pending(struct opp_table *opp_table)
 void _of_init_opp_table(struct opp_table *opp_table, struct device *dev, int index);
 void _of_clear_opp_table(struct opp_table *opp_table);
 struct opp_table *_managed_opp(struct device *dev, int index);
-void _of_opp_free_required_opps(struct opp_table *opp_table,
-				struct dev_pm_opp *opp);
+void _of_clear_opp(struct opp_table *opp_table, struct dev_pm_opp *opp);
 #else
 static inline void _of_init_opp_table(struct opp_table *opp_table, struct device *dev, int index) {}
 static inline void _of_clear_opp_table(struct opp_table *opp_table) {}
 static inline struct opp_table *_managed_opp(struct device *dev, int index) { return NULL; }
-static inline void _of_opp_free_required_opps(struct opp_table *opp_table,
-					      struct dev_pm_opp *opp) {}
+static inline void _of_clear_opp(struct opp_table *opp_table, struct dev_pm_opp *opp) {}
 #endif
 
 #ifdef CONFIG_DEBUG_FS