Commit baa8809f authored by Rafael J. Wysocki's avatar Rafael J. Wysocki Committed by Greg Kroah-Hartman
Browse files

PM / runtime: Optimize the use of device links 



If the device has no links to suppliers that should be used for
runtime PM (links with DEVICE_LINK_PM_RUNTIME set), there is no
reason to walk the list of suppliers for that device during
runtime suspend and resume.

Add a simple mechanism to detect that case and possibly avoid the
extra unnecessary overhead.

Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 21d5c57b

drivers/base/core.c

+13 −7
Original line number Diff line number Diff line
@@ -205,7 +205,8 @@ struct device_link *device_link_add(struct device *consumer, 
	if (!link)

		goto out;



	if ((flags & DL_FLAG_PM_RUNTIME) && (flags & DL_FLAG_RPM_ACTIVE)) {

	if (flags & DL_FLAG_PM_RUNTIME) {

		if (flags & DL_FLAG_RPM_ACTIVE) {

			if (pm_runtime_get_sync(supplier) < 0) {

				pm_runtime_put_noidle(supplier);

				kfree(link);
@@ -214,6 +215,8 @@ struct device_link *device_link_add(struct device *consumer, 
			}

			link->rpm_active = true;

		}

		pm_runtime_new_link(consumer);

	}

	get_device(supplier);

	link->supplier = supplier;

	INIT_LIST_HEAD(&link->s_node);
@@ -296,6 +299,9 @@ static void __device_link_del(struct device_link *link) 
	dev_info(link->consumer, "Dropping the link to %s\n",

		 dev_name(link->supplier));



	if (link->flags & DL_FLAG_PM_RUNTIME)

		pm_runtime_drop_link(link->consumer);



	list_del_rcu(&link->s_node);

	list_del_rcu(&link->c_node);

	call_srcu(&device_links_srcu, &link->rcu_head, __device_link_free_srcu);

drivers/base/power/runtime.c

+20 −3
Original line number Diff line number Diff line
@@ -305,6 +305,7 @@ static int __rpm_callback(int (*cb)(struct device *), struct device *dev) 
	__releases(&dev->power.lock) __acquires(&dev->power.lock)

{

	int retval, idx;

	bool use_links = dev->power.links_count > 0;



	if (dev->power.irq_safe) {

		spin_unlock(&dev->power.lock);
@@ -318,7 +319,7 @@ static int __rpm_callback(int (*cb)(struct device *), struct device *dev) 
		 * routine returns, so it is safe to read the status outside of

		 * the lock.

		 */

		if (dev->power.runtime_status == RPM_RESUMING) {

		if (use_links && dev->power.runtime_status == RPM_RESUMING) {

			idx = device_links_read_lock();



			retval = rpm_get_suppliers(dev);
@@ -341,8 +342,9 @@ static int __rpm_callback(int (*cb)(struct device *), struct device *dev) 
		 *

		 * Do that if resume fails too.

		 */

		if ((dev->power.runtime_status == RPM_SUSPENDING && !retval)

		    || (dev->power.runtime_status == RPM_RESUMING && retval)) {

		if (use_links

		    && ((dev->power.runtime_status == RPM_SUSPENDING && !retval)

		    || (dev->power.runtime_status == RPM_RESUMING && retval))) {

			idx = device_links_read_lock();



 fail:
@@ -1593,6 +1595,21 @@ void pm_runtime_put_suppliers(struct device *dev) 
	device_links_read_unlock(idx);

}



void pm_runtime_new_link(struct device *dev)

{

	spin_lock_irq(&dev->power.lock);

	dev->power.links_count++;

	spin_unlock_irq(&dev->power.lock);

}



void pm_runtime_drop_link(struct device *dev)

{

	spin_lock_irq(&dev->power.lock);

	WARN_ON(dev->power.links_count == 0);

	dev->power.links_count--;

	spin_unlock_irq(&dev->power.lock);

}



/**

 * pm_runtime_force_suspend - Force a device into suspend state if needed.

 * @dev: Device to suspend.

include/linux/pm.h

+1 −0
Original line number Diff line number Diff line
@@ -597,6 +597,7 @@ struct dev_pm_info { 
	unsigned int		use_autosuspend:1;

	unsigned int		timer_autosuspends:1;

	unsigned int		memalloc_noio:1;

	unsigned int		links_count;

	enum rpm_request	request;

	enum rpm_status		runtime_status;

	int			runtime_error;

include/linux/pm_runtime.h

+4 −0
Original line number Diff line number Diff line
@@ -58,6 +58,8 @@ extern void pm_runtime_set_memalloc_noio(struct device *dev, bool enable); 
extern void pm_runtime_clean_up_links(struct device *dev);

extern void pm_runtime_get_suppliers(struct device *dev);

extern void pm_runtime_put_suppliers(struct device *dev);

extern void pm_runtime_new_link(struct device *dev);

extern void pm_runtime_drop_link(struct device *dev);



static inline void pm_suspend_ignore_children(struct device *dev, bool enable)

{
@@ -192,6 +194,8 @@ static inline void pm_runtime_set_memalloc_noio(struct device *dev, 
static inline void pm_runtime_clean_up_links(struct device *dev) {}

static inline void pm_runtime_get_suppliers(struct device *dev) {}

static inline void pm_runtime_put_suppliers(struct device *dev) {}

static inline void pm_runtime_new_link(struct device *dev) {}

static inline void pm_runtime_drop_link(struct device *dev) {}



#endif /* !CONFIG_PM */

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