From: Ulf Hansson <ulf.hansson@linaro.org>
Date: Tue, 8 Jun 2021 09:02:49 +0000 (+0200)
Subject: PM: runtime: Allow unassigned ->runtime_suspend|resume callbacks
X-Git-Tag: block-5.14-2021-07-08~51^2~2^2~1
X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=63d00be69348fda431ae59aba6af268a5cf5058e;p=linux-2.6-block.git

PM: runtime: Allow unassigned ->runtime_suspend|resume callbacks

We are currently allowing ->runtime_idle() callbacks to be unassigned
without returning an error code from rpm_idle(). This has been useful to
avoid boilerplate code in drivers. Let's take this approach a step further,
by allowing also unassigned ->runtime_suspend|resume() callbacks.

In this way, a consumer/supplier device link can be used to let a consumer
device be power managed through its supplier device, without requiring
assigned ->runtime_suspend|resume() callbacks for the consumer device, for
example.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---

diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index 68bebbf81347..8a66eaf731e4 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -345,7 +345,7 @@ static void rpm_suspend_suppliers(struct device *dev)
 static int __rpm_callback(int (*cb)(struct device *), struct device *dev)
 	__releases(&dev->power.lock) __acquires(&dev->power.lock)
 {
-	int retval, idx;
+	int retval = 0, idx;
 	bool use_links = dev->power.links_count > 0;
 
 	if (dev->power.irq_safe) {
@@ -373,7 +373,8 @@ static int __rpm_callback(int (*cb)(struct device *), struct device *dev)
 		}
 	}
 
-	retval = cb(dev);
+	if (cb)
+		retval = cb(dev);
 
 	if (dev->power.irq_safe) {
 		spin_lock(&dev->power.lock);
@@ -484,9 +485,6 @@ static int rpm_callback(int (*cb)(struct device *), struct device *dev)
 {
 	int retval;
 
-	if (!cb)
-		return -ENOSYS;
-
 	if (dev->power.memalloc_noio) {
 		unsigned int noio_flag;