PM / Sleep: Mark devices involved in wakeup signaling during suspend

The generic PM domains code in drivers/base/power/domain.c has
to avoid powering off domains that provide power to wakeup devices
during system suspend.  Currently, however, this only works for
wakeup devices directly belonging to the given domain and not for
their children (or the children of their children and so on).
Thus, if there's a wakeup device whose parent belongs to a power
domain handled by the generic PM domains code, the domain will be
powered off during system suspend preventing the device from
signaling wakeup.

To address this problem introduce a device flag, power.wakeup_path,
that will be set during system suspend for all wakeup devices,
their parents, the parents of their parents and so on.  This way,
all wakeup paths in the device hierarchy will be marked and the
generic PM domains code will only need to avoid powering off
domains containing devices whose power.wakeup_path is set.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

drivers/base/power/domain.c

@@ -714,7 +714,7 @@ static int pm_genpd_suspend_noirq(struct device *dev)
 	if (ret)
 		return ret;
 
-	if (device_may_wakeup(dev)
+	if (dev->power.wakeup_path
 	    && genpd->active_wakeup && genpd->active_wakeup(dev))
 		return 0;
 
@@ -938,7 +938,7 @@ static int pm_genpd_dev_poweroff_noirq(struct device *dev)
 	if (ret)
 		return ret;
 
-	if (device_may_wakeup(dev)
+	if (dev->power.wakeup_path
 	    && genpd->active_wakeup && genpd->active_wakeup(dev))
 		return 0;
 

drivers/base/power/main.c

@@ -902,7 +902,11 @@ static int __device_suspend(struct device *dev, pm_message_t state, bool async)
 	}
 
  End:
-	dev->power.is_suspended = !error;
+	if (!error) {
+		dev->power.is_suspended = true;
+		if (dev->power.wakeup_path && dev->parent)
+			dev->parent->power.wakeup_path = true;
+	}
 
 	device_unlock(dev);
 	complete_all(&dev->power.completion);
@@ -999,6 +1003,8 @@ static int device_prepare(struct device *dev, pm_message_t state)
 
 	device_lock(dev);
 
+	dev->power.wakeup_path = device_may_wakeup(dev);
+
 	if (dev->pm_domain) {
 		pm_dev_dbg(dev, state, "preparing power domain ");
 		if (dev->pm_domain->ops.prepare)

include/linux/pm.h

@@ -448,6 +448,7 @@ struct dev_pm_info {
 	struct list_head	entry;
 	struct completion	completion;
 	struct wakeup_source	*wakeup;
+	bool			wakeup_path:1;
 #else
 	unsigned int		should_wakeup:1;
 #endif