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Commit 08e75e75 authored by Javi Merino's avatar Javi Merino Committed by MyungJoo Ham
Browse files

PM / devfreq: cache the last call to get_dev_status() 



The return value of get_dev_status() can be reused.  Cache it so that
other parts of the kernel can reuse it instead of having to call the
same function again.

Cc: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: default avatarJavi Merino <javi.merino@arm.com>
Signed-off-by: default avatarMyungJoo Ham <myungjoo.ham@samsung.com>
parent 9348da2f

drivers/devfreq/governor_simpleondemand.c

+18 −15
Original line number Diff line number Diff line
@@ -21,17 +21,20 @@ 
static int devfreq_simple_ondemand_func(struct devfreq *df,

					unsigned long *freq)

{

	struct devfreq_dev_status stat;

	int err = df->profile->get_dev_status(df->dev.parent, &stat);

	int err;

	struct devfreq_dev_status *stat;

	unsigned long long a, b;

	unsigned int dfso_upthreshold = DFSO_UPTHRESHOLD;

	unsigned int dfso_downdifferential = DFSO_DOWNDIFFERENCTIAL;

	struct devfreq_simple_ondemand_data *data = df->data;

	unsigned long max = (df->max_freq) ? df->max_freq : UINT_MAX;



	err = devfreq_update_stats(df);

	if (err)

		return err;



	stat = &df->last_status;



	if (data) {

		if (data->upthreshold)

			dfso_upthreshold = data->upthreshold;
@@ -43,41 +46,41 @@ static int devfreq_simple_ondemand_func(struct devfreq *df, 
		return -EINVAL;



	/* Assume MAX if it is going to be divided by zero */

	if (stat.total_time == 0) {

	if (stat->total_time == 0) {

		*freq = max;

		return 0;

	}



	/* Prevent overflow */

	if (stat.busy_time >= (1 << 24) || stat.total_time >= (1 << 24)) {

		stat.busy_time >>= 7;

		stat.total_time >>= 7;

	if (stat->busy_time >= (1 << 24) || stat->total_time >= (1 << 24)) {

		stat->busy_time >>= 7;

		stat->total_time >>= 7;

	}



	/* Set MAX if it's busy enough */

	if (stat.busy_time * 100 >

	    stat.total_time * dfso_upthreshold) {

	if (stat->busy_time * 100 >

	    stat->total_time * dfso_upthreshold) {

		*freq = max;

		return 0;

	}



	/* Set MAX if we do not know the initial frequency */

	if (stat.current_frequency == 0) {

	if (stat->current_frequency == 0) {

		*freq = max;

		return 0;

	}



	/* Keep the current frequency */

	if (stat.busy_time * 100 >

	    stat.total_time * (dfso_upthreshold - dfso_downdifferential)) {

		*freq = stat.current_frequency;

	if (stat->busy_time * 100 >

	    stat->total_time * (dfso_upthreshold - dfso_downdifferential)) {

		*freq = stat->current_frequency;

		return 0;

	}



	/* Set the desired frequency based on the load */

	a = stat.busy_time;

	a *= stat.current_frequency;

	b = div_u64(a, stat.total_time);

	a = stat->busy_time;

	a *= stat->current_frequency;

	b = div_u64(a, stat->total_time);

	b *= 100;

	b = div_u64(b, (dfso_upthreshold - dfso_downdifferential / 2));

	*freq = (unsigned long) b;

include/linux/devfreq.h

+15 −0
Original line number Diff line number Diff line
@@ -161,6 +161,7 @@ struct devfreq { 
	struct delayed_work work;



	unsigned long previous_freq;

	struct devfreq_dev_status last_status;



	void *data; /* private data for governors */
@@ -204,6 +205,15 @@ extern int devm_devfreq_register_opp_notifier(struct device *dev, 
extern void devm_devfreq_unregister_opp_notifier(struct device *dev,

						struct devfreq *devfreq);



/**

 * devfreq_update_stats() - update the last_status pointer in struct devfreq

 * @df:		the devfreq instance whose status needs updating

 */

static inline int devfreq_update_stats(struct devfreq *df)

{

	return df->profile->get_dev_status(df->dev.parent, &df->last_status);

}



#if IS_ENABLED(CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND)

/**

 * struct devfreq_simple_ondemand_data - void *data fed to struct devfreq
@@ -289,6 +299,11 @@ static inline void devm_devfreq_unregister_opp_notifier(struct device *dev, 
							struct devfreq *devfreq)

{

}



static inline int devfreq_update_stats(struct devfreq *df)

{

	return -EINVAL;

}

#endif /* CONFIG_PM_DEVFREQ */



#endif /* __LINUX_DEVFREQ_H__ */