linux-kernel - [PATCH 1/2] PM: runtime: Improve path in rpm

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Message-Id: <20210528091147.11541-1-ulf.hansson@linaro.org>
Date:   Fri, 28 May 2021 11:11:47 +0200
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     "Rafael J . Wysocki" <rjw@...ysocki.net>, linux-pm@...r.kernel.org
Cc:     Ulf Hansson <ulf.hansson@...aro.org>,
        Saravana Kannan <saravanak@...gle.com>,
        Alan Stern <stern@...land.harvard.edu>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Tony Lindgren <tony@...mide.com>,
        Kevin Hilman <khilman@...nel.org>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH 1/2] PM: runtime: Improve path in rpm_idle() when no callback

When pm_runtime_no_callbacks() has been called for a struct device to set
the dev->power.no_callbacks flag for it, it enables rpm_idle() to take a
slightly quicker path by assuming that a ->runtime_idle() callback would
have returned 0 to indicate success.

A device that does not have the dev->power.no_callbacks flag set for it,
may still be missing a corresponding ->runtime_idle() callback, in which
case the slower path in rpm_idle() is taken. Let's improve the behaviour
for this case, by aligning code to the quicker path.

Signed-off-by: Ulf Hansson <ulf.hansson@...aro.org>
---
 drivers/base/power/runtime.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index b570848d23e0..68bebbf81347 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -446,7 +446,10 @@ static int rpm_idle(struct device *dev, int rpmflags)
 	/* Pending requests need to be canceled. */
 	dev->power.request = RPM_REQ_NONE;
 
-	if (dev->power.no_callbacks)
+	callback = RPM_GET_CALLBACK(dev, runtime_idle);
+
+	/* If no callback assume success. */
+	if (!callback || dev->power.no_callbacks)
 		goto out;
 
 	/* Carry out an asynchronous or a synchronous idle notification. */
@@ -462,10 +465,7 @@ static int rpm_idle(struct device *dev, int rpmflags)
 
 	dev->power.idle_notification = true;
 
-	callback = RPM_GET_CALLBACK(dev, runtime_idle);
-
-	if (callback)
-		retval = __rpm_callback(callback, dev);
+	retval = __rpm_callback(callback, dev);
 
 	dev->power.idle_notification = false;
 	wake_up_all(&dev->power.wait_queue);
-- 
2.25.1