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Commit 8c73b428 authored by Rafael J. Wysocki's avatar Rafael J. Wysocki Committed by Greg Kroah-Hartman
Browse files

PM / sleep: Make async suspend/resume of devices use device links 



Make the device suspend/resume part of the core system
suspend/resume code use device links to ensure that supplier
and consumer devices will be suspended and resumed in the right
order in case of async suspend/resume.

The idea, roughly, is to use dpm_wait() to wait for all consumers
before a supplier device suspend and to wait for all suppliers
before a consumer device resume.

Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: default avatarMarek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 9ed98953

drivers/base/power/main.c

+79 −6
Original line number Diff line number Diff line
@@ -246,6 +246,62 @@ static void dpm_wait_for_children(struct device *dev, bool async) 
       device_for_each_child(dev, &async, dpm_wait_fn);

}



static void dpm_wait_for_suppliers(struct device *dev, bool async)

{

	struct device_link *link;

	int idx;



	idx = device_links_read_lock();



	/*

	 * If the supplier goes away right after we've checked the link to it,

	 * we'll wait for its completion to change the state, but that's fine,

	 * because the only things that will block as a result are the SRCU

	 * callbacks freeing the link objects for the links in the list we're

	 * walking.

	 */

	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node)

		if (READ_ONCE(link->status) != DL_STATE_DORMANT)

			dpm_wait(link->supplier, async);



	device_links_read_unlock(idx);

}



static void dpm_wait_for_superior(struct device *dev, bool async)

{

	dpm_wait(dev->parent, async);

	dpm_wait_for_suppliers(dev, async);

}



static void dpm_wait_for_consumers(struct device *dev, bool async)

{

	struct device_link *link;

	int idx;



	idx = device_links_read_lock();



	/*

	 * The status of a device link can only be changed from "dormant" by a

	 * probe, but that cannot happen during system suspend/resume.  In

	 * theory it can change to "dormant" at that time, but then it is

	 * reasonable to wait for the target device anyway (eg. if it goes

	 * away, it's better to wait for it to go away completely and then

	 * continue instead of trying to continue in parallel with its

	 * unregistration).

	 */

	list_for_each_entry_rcu(link, &dev->links.consumers, s_node)

		if (READ_ONCE(link->status) != DL_STATE_DORMANT)

			dpm_wait(link->consumer, async);



	device_links_read_unlock(idx);

}



static void dpm_wait_for_subordinate(struct device *dev, bool async)

{

	dpm_wait_for_children(dev, async);

	dpm_wait_for_consumers(dev, async);

}



/**

 * pm_op - Return the PM operation appropriate for given PM event.

 * @ops: PM operations to choose from.
@@ -490,7 +546,7 @@ static int device_resume_noirq(struct device *dev, pm_message_t state, bool asyn 
	if (!dev->power.is_noirq_suspended)

		goto Out;



	dpm_wait(dev->parent, async);

	dpm_wait_for_superior(dev, async);



	if (dev->pm_domain) {

		info = "noirq power domain ";
@@ -620,7 +676,7 @@ static int device_resume_early(struct device *dev, pm_message_t state, bool asyn 
	if (!dev->power.is_late_suspended)

		goto Out;



	dpm_wait(dev->parent, async);

	dpm_wait_for_superior(dev, async);



	if (dev->pm_domain) {

		info = "early power domain ";
@@ -752,7 +808,7 @@ static int device_resume(struct device *dev, pm_message_t state, bool async) 
		goto Complete;

	}



	dpm_wait(dev->parent, async);

	dpm_wait_for_superior(dev, async);

	dpm_watchdog_set(&wd, dev);

	device_lock(dev);
@@ -1040,7 +1096,7 @@ static int __device_suspend_noirq(struct device *dev, pm_message_t state, bool a 
	if (dev->power.syscore || dev->power.direct_complete)

		goto Complete;



	dpm_wait_for_children(dev, async);

	dpm_wait_for_subordinate(dev, async);



	if (dev->pm_domain) {

		info = "noirq power domain ";
@@ -1187,7 +1243,7 @@ static int __device_suspend_late(struct device *dev, pm_message_t state, bool as 
	if (dev->power.syscore || dev->power.direct_complete)

		goto Complete;



	dpm_wait_for_children(dev, async);

	dpm_wait_for_subordinate(dev, async);



	if (dev->pm_domain) {

		info = "late power domain ";
@@ -1344,6 +1400,22 @@ static int legacy_suspend(struct device *dev, pm_message_t state, 
	return error;

}



static void dpm_clear_suppliers_direct_complete(struct device *dev)

{

	struct device_link *link;

	int idx;



	idx = device_links_read_lock();



	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node) {

		spin_lock_irq(&link->supplier->power.lock);

		link->supplier->power.direct_complete = false;

		spin_unlock_irq(&link->supplier->power.lock);

	}



	device_links_read_unlock(idx);

}



/**

 * device_suspend - Execute "suspend" callbacks for given device.

 * @dev: Device to handle.
@@ -1360,7 +1432,7 @@ static int __device_suspend(struct device *dev, pm_message_t state, bool async) 
	TRACE_DEVICE(dev);

	TRACE_SUSPEND(0);



	dpm_wait_for_children(dev, async);

	dpm_wait_for_subordinate(dev, async);



	if (async_error)

		goto Complete;
@@ -1456,6 +1528,7 @@ static int __device_suspend(struct device *dev, pm_message_t state, bool async) 


			spin_unlock_irq(&parent->power.lock);

		}

		dpm_clear_suppliers_direct_complete(dev);

	}



	device_unlock(dev);