[PATCH] PM / runtime: Asynchronous "idle" in pm_runtime_allow()

From	"Rafael J. Wysocki" <rjw@rjwysocki.net>
Newsgroups	linux.kernel
Subject	[PATCH] PM / runtime: Asynchronous "idle" in pm_runtime_allow()
Date	2016-06-29 02:50 +0200
Message-ID	<rPbRv-5D5-5@gated-at.bofh.it> (permalink)
Organization	linux.* mail to news gateway

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From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Arjan reports that it takes a relatively long time to enable runtime
PM for multiple devices at system startup, because all writes to the
"control" attribute in sysfs are handled synchronously and if the
device is suspended as a result of the write, it will block until
that operation is complete.

That may be avoided by passing the RPM_ASYNC flag to rpm_idle()
in pm_runtime_allow() which will make it execute the device's
"idle" callback asynchronously, so writes to "control" changing
it from "on" to "auto" will return without waiting.

Reported-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 drivers/base/power/runtime.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Index: linux-pm/drivers/base/power/runtime.c
===================================================================
--- linux-pm.orig/drivers/base/power/runtime.c
+++ linux-pm/drivers/base/power/runtime.c
@@ -1256,7 +1256,7 @@ void pm_runtime_allow(struct device *dev
 
 	dev->power.runtime_auto = true;
 	if (atomic_dec_and_test(&dev->power.usage_count))
-		rpm_idle(dev, RPM_AUTO);
+		rpm_idle(dev, RPM_AUTO | RPM_ASYNC);
 
  out:
 	spin_unlock_irq(&dev->power.lock);

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[PATCH] PM / runtime: Asynchronous "idle" in pm_runtime_allow() "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-06-29 02:50 +0200
  Re: [PATCH] PM / runtime: Asynchronous "idle" in pm_runtime_allow() Alan Stern <stern@rowland.harvard.edu> - 2016-06-29 16:10 +0200
    Re: [PATCH] PM / runtime: Asynchronous "idle" in pm_runtime_allow() Lukas Wunner <lukas@wunner.de> - 2016-06-29 17:00 +0200
  Re: [PATCH] PM / runtime: Asynchronous "idle" in pm_runtime_allow() Ulf Hansson <ulf.hansson@linaro.org> - 2016-06-29 19:00 +0200
  Re: [PATCH] PM / runtime: Asynchronous "idle" in pm_runtime_allow() Kevin Hilman <khilman@baylibre.com> - 2016-07-01 00:50 +0200

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