[PATCH v3 1/2] PM / sleep: Let devices force direct_complete

[Tomeu Vizoso]

Introduce a new per-device flag power.force_direct_complete that will
instruct the PM core to ignore the runtime PM status of its descendants
when deciding whether to let this device remain in runtime suspend when
the system goes into a sleep power state.

This is needed because otherwise it would be needed to get dozens of
drivers to implement the prepare() callback and be runtime PM active
even if they don't have a 1-to-1 relationship with a piece of HW.

Signed-off-by: Tomeu Vizoso <tomeu.vizoso@xxxxxxxxxxxxx>
---
 drivers/base/power/main.c | 13 +++++++++----
 include/linux/pm.h        |  1 +
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
index 3d874ec..728c2dc 100644
--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -1438,7 +1438,9 @@ static int __device_suspend(struct device *dev, pm_message_t state, bool async)
 		if (parent) {
 			spin_lock_irq(&parent->power.lock);
 
-			dev->parent->power.direct_complete = false;
+			if (!dev->parent->power.force_direct_complete)
+				dev->parent->power.direct_complete = false;
+
 			if (dev->power.wakeup_path
 			    && !dev->parent->power.ignore_children)
 				dev->parent->power.wakeup_path = true;
@@ -1605,9 +1607,12 @@ static int device_prepare(struct device *dev, pm_message_t state)
 	 * will do the same thing with all of its descendants".  This only
 	 * applies to suspend transitions, however.
 	 */
-	spin_lock_irq(&dev->power.lock);
-	dev->power.direct_complete = ret > 0 && state.event == PM_EVENT_SUSPEND;
-	spin_unlock_irq(&dev->power.lock);
+	if (state.event == PM_EVENT_SUSPEND) {
+		spin_lock_irq(&dev->power.lock);
+		dev->power.direct_complete = ret > 0 ||
+			dev->power.force_direct_complete;
+		spin_unlock_irq(&dev->power.lock);
+	}
 	return 0;
 }
 
diff --git a/include/linux/pm.h b/include/linux/pm.h
index 2d29c64..2e41cfd 100644
--- a/include/linux/pm.h
+++ b/include/linux/pm.h
@@ -553,6 +553,7 @@ struct dev_pm_info {
 	bool			ignore_children:1;
 	bool			early_init:1;	/* Owned by the PM core */
 	bool			direct_complete:1;	/* Owned by the PM core */
+	bool			force_direct_complete:1;
 	spinlock_t		lock;
 #ifdef CONFIG_PM_SLEEP
 	struct list_head	entry;
-- 
2.3.5

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