Commit 520a552f authored by Rafael J. Wysocki's avatar Rafael J. Wysocki
Browse files

PM: sleep: Avoid unnecessary checks in device_prepare_smart_suspend() 



Add an optimization (on top of previous changes) to avoid calling
pm_runtime_blocked(), which involves acquiring the device's PM spinlock,
for devices with no PM callbacks and runtime PM "blocked".

Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: default avatarUlf Hansson <ulf.hansson@linaro.org>
Link: https://patch.msgid.link/2978873.e9J7NaK4W3@rjwysocki.net
parent bca84a7b

drivers/base/power/main.c

+9 −7
Original line number Diff line number Diff line
@@ -1796,16 +1796,14 @@ static void device_prepare_smart_suspend(struct device *dev) 


	/*

	 * The "smart suspend" feature is enabled for devices whose drivers ask

	 * for it and for devices without PM callbacks unless runtime PM is

	 * disabled and enabling it is blocked for them.

	 * for it and for devices without PM callbacks.

	 *

	 * However, if "smart suspend" is not enabled for the device's parent

	 * or any of its suppliers that take runtime PM into account, it cannot

	 * be enabled for the device either.

	 */

	dev->power.smart_suspend = (dev->power.no_pm_callbacks ||

		dev_pm_test_driver_flags(dev, DPM_FLAG_SMART_SUSPEND)) &&

		!pm_runtime_blocked(dev);

	dev->power.smart_suspend = dev->power.no_pm_callbacks ||

		dev_pm_test_driver_flags(dev, DPM_FLAG_SMART_SUSPEND);



	if (!dev_pm_smart_suspend(dev))

		return;
@@ -1843,6 +1841,7 @@ static void device_prepare_smart_suspend(struct device *dev) 
static int device_prepare(struct device *dev, pm_message_t state)

{

	int (*callback)(struct device *) = NULL;

	bool no_runtime_pm;

	int ret = 0;



	/*
@@ -1858,7 +1857,7 @@ static int device_prepare(struct device *dev, pm_message_t state) 
	 * suspend-resume cycle is complete, so prepare to trigger a warning on

	 * subsequent attempts to enable it.

	 */

	pm_runtime_block_if_disabled(dev);

	no_runtime_pm = pm_runtime_block_if_disabled(dev);



	if (dev->power.syscore)

		return 0;
@@ -1893,7 +1892,10 @@ static int device_prepare(struct device *dev, pm_message_t state) 
		pm_runtime_put(dev);

		return ret;

	}

	/* Do not enable "smart suspend" for devices without runtime PM. */

	if (!no_runtime_pm)

		device_prepare_smart_suspend(dev);



	/*

	 * A positive return value from ->prepare() means "this device appears

	 * to be runtime-suspended and its state is fine, so if it really is

drivers/base/power/runtime.c

+7 −2
Original line number Diff line number Diff line
@@ -1460,14 +1460,19 @@ int pm_runtime_barrier(struct device *dev) 
}

EXPORT_SYMBOL_GPL(pm_runtime_barrier);



void pm_runtime_block_if_disabled(struct device *dev)

bool pm_runtime_block_if_disabled(struct device *dev)

{

	bool ret;



	spin_lock_irq(&dev->power.lock);



	if (dev->power.disable_depth && dev->power.last_status == RPM_INVALID)

	ret = dev->power.disable_depth && dev->power.last_status == RPM_INVALID;

	if (ret)

		dev->power.last_status = RPM_BLOCKED;



	spin_unlock_irq(&dev->power.lock);



	return ret;

}



void pm_runtime_unblock(struct device *dev)

include/linux/pm_runtime.h

+2 −2
Original line number Diff line number Diff line
@@ -77,7 +77,7 @@ extern int pm_runtime_get_if_in_use(struct device *dev); 
extern int pm_schedule_suspend(struct device *dev, unsigned int delay);

extern int __pm_runtime_set_status(struct device *dev, unsigned int status);

extern int pm_runtime_barrier(struct device *dev);

extern void pm_runtime_block_if_disabled(struct device *dev);

extern bool pm_runtime_block_if_disabled(struct device *dev);

extern void pm_runtime_unblock(struct device *dev);

extern void pm_runtime_enable(struct device *dev);

extern void __pm_runtime_disable(struct device *dev, bool check_resume);
@@ -274,7 +274,7 @@ static inline int pm_runtime_get_if_active(struct device *dev) 
static inline int __pm_runtime_set_status(struct device *dev,

					    unsigned int status) { return 0; }

static inline int pm_runtime_barrier(struct device *dev) { return 0; }

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

static inline bool pm_runtime_block_if_disabled(struct device *dev) { return true; }

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

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

static inline void __pm_runtime_disable(struct device *dev, bool c) {}