patches/0408-PM-runtime-Drop-children-check-from-__pm_runtime_set.patch

From ebb50b76c08f058dfa56ba5a7bb314474a0a7754 Mon Sep 17 00:00:00 2001
From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Date: Thu, 16 Nov 2017 22:51:22 +0100
Subject: [PATCH 0408/1795] 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>
(cherry picked from commit f8817f61e8215b0ff1b73a0d33fa04ef9e6bce8b)
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
 Documentation/power/runtime_pm.txt |  3 +--
 drivers/base/power/runtime.c       | 31 +++++++++++-------------------
 2 files changed, 12 insertions(+), 22 deletions(-)

diff --git a/Documentation/power/runtime_pm.txt b/Documentation/power/runtime_pm.txt
index 625549d4c74a..0fde3dcf077a 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 b2b1eece0db1..3da090e7ed05 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -1102,29 +1102,13 @@ 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);
 
 		/*
@@ -1308,6 +1292,13 @@ 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);
-- 
2.19.0