PM / runtime: Drop children check from __pm_runtime_set_status()

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().

Fixes: a8636c89648a (PM / Runtime: Don't allow to suspend a device with an active child)
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Reviewed-by: Johan Hovold <johan@kernel.org>

2 files changed, 12 insertions, 22 deletions

diff --git a/Documentation/power/runtime_pm.txt b/Documentation/power/runtime_pm.txt
index 57af2f7963ee..937e33c46211 100644
--- a/Documentation/power/runtime_pm.txt
+++ b/Documentation/power/runtime_pm.txt
@@ -435,8 +435,7 @@ drivers/base/power/runtime.c and include/linux/pm_runtime.h:
       PM status to 'suspended' and update its parent's counter of 'active'
       children as appropriate (it is only valid to use this function if
       'power.runtime_error' is set or 'power.disable_depth' is greater than
-      zero); it will fail and return an error code if the device has a child
-      which is active and the 'power.ignore_children' flag is unset
+      zero)
 
   bool pm_runtime_active(struct device *dev);
     - return true if the device's runtime PM status is 'active' or its
diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index 2362b9e9701e..027d159ac381 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -1101,29 +1101,13 @@ int __pm_runtime_set_status(struct device *dev, unsigned int status)
                 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 +1291,13 @@ void pm_runtime_enable(struct device *dev)
         else
                 dev_warn(dev, "Unbalanced %s!\n", __func__);
 
+        WARN(!dev->power.disable_depth &&
+             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);