linux-kernel - Re: [PATCH] PM / runtime: Asynchronous "idle" in pm_runtime

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Message-ID: <m2poqyqomy.fsf@baylibre.com>
Date:	Thu, 30 Jun 2016 15:48:37 -0700
From:	Kevin Hilman <khilman@...libre.com>
To:	"Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:	Linux PM list <linux-pm@...r.kernel.org>,
	Arjan van de Ven <arjan@...ux.intel.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Alan Stern <stern@...land.harvard.edu>,
	Ulf Hansson <ulf.hansson@...aro.org>
Subject: Re: [PATCH] PM / runtime: Asynchronous "idle" in pm_runtime_allow()

"Rafael J. Wysocki" <rjw@...ysocki.net> writes:

> From: Rafael J. Wysocki <rafael.j.wysocki@...el.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@...ux.intel.com>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

Reviewed-by: Kevin Hilman <khilman@...libre.com>