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Subject[PATCH] PM / runtime: Drop children check from __pm_runtime_set_status()
Date
From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

The check for "active" children in __pm_runtime_set_status(), when
trying to set the parent device status to "suspended", doesn't
really make sense, because in fact it is not invalid to set the
status of a device with runtime PM disabled to "suspended" in any
case. It is invalid to enable runtime PM for a device with its
status set to "suspended" while its child_count reference counter
is nonzero, but the check in __pm_runtime_set_status() doesn't
really cover that situation.

For this reason, drop the children check from __pm_runtime_set_status()
and add a check against child_count reference counters of "suspended"
devices to pm_runtime_enable().

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
drivers/base/power/runtime.c | 30 ++++++++++--------------------
1 file changed, 10 insertions(+), 20 deletions(-)

Index: linux-pm/drivers/base/power/runtime.c
===================================================================
--- linux-pm.orig/drivers/base/power/runtime.c
+++ linux-pm/drivers/base/power/runtime.c
@@ -1101,29 +1101,13 @@ int __pm_runtime_set_status(struct devic
goto out;
}

- if (dev->power.runtime_status == status)
+ if (dev->power.runtime_status == status || !parent)
goto out_set;

if (status == RPM_SUSPENDED) {
- /*
- * It is invalid to suspend a device with an active child,
- * unless it has been set to ignore its children.
- */
- if (!dev->power.ignore_children &&
- atomic_read(&dev->power.child_count)) {
- dev_err(dev, "runtime PM trying to suspend device but active child\n");
- error = -EBUSY;
- goto out;
- }
-
- if (parent) {
- atomic_add_unless(&parent->power.child_count, -1, 0);
- notify_parent = !parent->power.ignore_children;
- }
- goto out_set;
- }
-
- if (parent) {
+ atomic_add_unless(&parent->power.child_count, -1, 0);
+ notify_parent = !parent->power.ignore_children;
+ } else {
spin_lock_nested(&parent->power.lock, SINGLE_DEPTH_NESTING);

/*
@@ -1307,6 +1291,12 @@ void pm_runtime_enable(struct device *de
else
dev_warn(dev, "Unbalanced %s!\n", __func__);

+ WARN(dev->power.runtime_status == RPM_SUSPENDED &&
+ !dev->power.ignore_children &&
+ atomic_read(&dev->power.child_count) > 0,
+ "Enabling runtime PM for inactive device (%s) with active children\n",
+ dev_name(dev));
+
spin_unlock_irqrestore(&dev->power.lock, flags);
}
EXPORT_SYMBOL_GPL(pm_runtime_enable);
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