Commit 5244f5e2 authored by Rafael J. Wysocki's avatar Rafael J. Wysocki
Browse files

PM: runtime: Defer suspending suppliers 

Because the PM-runtime status of the device is not updated in
__rpm_callback(), attempts to suspend the suppliers of the given
device triggered by the rpm_put_suppliers() call in there may
cause a supplier to be suspended completely before the status of
the consumer is updated to RPM_SUSPENDED, which is confusing.

To avoid that (1) modify __rpm_callback() to only decrease the
PM-runtime usage counter of each supplier and (2) make rpm_suspend()
try to suspend the suppliers after changing the consumer's status to
RPM_SUSPENDED, in analogy with the device's parent.

Link: https://lore.kernel.org/linux-pm/CAPDyKFqm06KDw_p8WXsM4dijDbho4bb6T4k50UqqvR1_COsp8g@mail.gmail.com/


Fixes: 21d5c57b ("PM / runtime: Use device links")
Reported-by: default avatarelaine.zhang <zhangqing@rock-chips.com>
Diagnosed-by: default avatarUlf Hansson <ulf.hansson@linaro.org>
Reviewed-by: default avatarUlf Hansson <ulf.hansson@linaro.org>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 0d02ec6b

drivers/base/power/runtime.c

+39 −6
Original line number Diff line number Diff line
@@ -305,7 +305,7 @@ static int rpm_get_suppliers(struct device *dev) 
	return 0;

}



static void rpm_put_suppliers(struct device *dev)

static void __rpm_put_suppliers(struct device *dev, bool try_to_suspend)

{

	struct device_link *link;
@@ -313,10 +313,30 @@ static void rpm_put_suppliers(struct device *dev) 
				device_links_read_lock_held()) {



		while (refcount_dec_not_one(&link->rpm_active))

			pm_runtime_put(link->supplier);

			pm_runtime_put_noidle(link->supplier);



		if (try_to_suspend)

			pm_request_idle(link->supplier);

	}

}



static void rpm_put_suppliers(struct device *dev)

{

	__rpm_put_suppliers(dev, true);

}



static void rpm_suspend_suppliers(struct device *dev)

{

	struct device_link *link;

	int idx = device_links_read_lock();



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

				device_links_read_lock_held())

		pm_request_idle(link->supplier);



	device_links_read_unlock(idx);

}



/**

 * __rpm_callback - Run a given runtime PM callback for a given device.

 * @cb: Runtime PM callback to run.
@@ -344,8 +364,10 @@ static int __rpm_callback(int (*cb)(struct device *), struct device *dev) 
			idx = device_links_read_lock();



			retval = rpm_get_suppliers(dev);

			if (retval)

			if (retval) {

				rpm_put_suppliers(dev);

				goto fail;

			}



			device_links_read_unlock(idx);

		}
@@ -368,9 +390,9 @@ static int __rpm_callback(int (*cb)(struct device *), struct device *dev) 
		    || (dev->power.runtime_status == RPM_RESUMING && retval))) {

			idx = device_links_read_lock();



 fail:

			rpm_put_suppliers(dev);

			__rpm_put_suppliers(dev, false);



fail:

			device_links_read_unlock(idx);

		}
@@ -642,8 +664,11 @@ static int rpm_suspend(struct device *dev, int rpmflags) 
		goto out;

	}



	if (dev->power.irq_safe)

		goto out;



	/* Maybe the parent is now able to suspend. */

	if (parent && !parent->power.ignore_children && !dev->power.irq_safe) {

	if (parent && !parent->power.ignore_children) {

		spin_unlock(&dev->power.lock);



		spin_lock(&parent->power.lock);
@@ -652,6 +677,14 @@ static int rpm_suspend(struct device *dev, int rpmflags) 


		spin_lock(&dev->power.lock);

	}

	/* Maybe the suppliers are now able to suspend. */

	if (dev->power.links_count > 0) {

		spin_unlock_irq(&dev->power.lock);



		rpm_suspend_suppliers(dev);



		spin_lock_irq(&dev->power.lock);

	}



 out:

	trace_rpm_return_int_rcuidle(dev, _THIS_IP_, retval);