PM / devfreq: Cache OPP table reference in devfreq

The OPP table can be used often in devfreq. Trying to get it each time can
be expensive, so cache it in the devfreq struct.
Signed-off-by: Saravana Kannan <saravanak@google.com>
Acked-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Acked-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org>
[ Viresh: Added a blank line ]
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

drivers/devfreq/devfreq.c

@@ -757,6 +757,9 @@ static void devfreq_dev_release(struct device *dev)
 	if (devfreq->profile->exit)
 		devfreq->profile->exit(devfreq->dev.parent);
 
+	if (devfreq->opp_table)
+		dev_pm_opp_put_opp_table(devfreq->opp_table);
+
 	mutex_destroy(&devfreq->lock);
 	kfree(devfreq);
 }
@@ -844,6 +847,10 @@ struct devfreq *devfreq_add_device(struct device *dev,
 	}
 
 	devfreq->suspend_freq = dev_pm_opp_get_suspend_opp_freq(dev);
+	devfreq->opp_table = dev_pm_opp_get_opp_table(dev);
+	if (IS_ERR(devfreq->opp_table))
+		devfreq->opp_table = NULL;
+
 	atomic_set(&devfreq->suspend_count, 0);
 
 	dev_set_name(&devfreq->dev, "%s", dev_name(dev));

include/linux/devfreq.h

@@ -137,6 +137,7 @@ struct devfreq_stats {
  *		using devfreq.
  * @profile:	device-specific devfreq profile
  * @governor:	method how to choose frequency based on the usage.
+ * @opp_table:	Reference to OPP table of dev.parent, if one exists.
  * @nb:		notifier block used to notify devfreq object that it should
  *		reevaluate operable frequencies. Devfreq users may use
  *		devfreq.nb to the corresponding register notifier call chain.
@@ -173,6 +174,7 @@ struct devfreq {
 	struct device dev;
 	struct devfreq_dev_profile *profile;
 	const struct devfreq_governor *governor;
+	struct opp_table *opp_table;
 	struct notifier_block nb;
 	struct delayed_work work;