linux-kernel - Re: [PATCH] PM: Make it possible to avoid wakeup events from being lost

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Message-ID: <20100701133208.GA1285@ucw.cz>
Date:	Thu, 1 Jul 2010 15:32:08 +0200
From:	Pavel Machek <pavel@....cz>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	linux-pm@...ts.linux-foundation.org,
	Alan Stern <stern@...land.harvard.edu>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Neil Brown <neilb@...e.de>,
	Matthew Garrett <mjg59@...f.ucam.org>,
	mark gross <640e9920@...il.com>,
	Arve Hj??nnev??g <arve@...roid.com>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Florian Mickler <florian@...kler.org>,
	linux-pci@...r.kernel.org, Jesse Barnes <jbarnes@...tuousgeek.org>
Subject: Re: [PATCH] PM: Make it possible to avoid wakeup events from being
 lost

Hi!

> @@ -114,3 +114,17 @@ Description:
>  		if this file contains "1", which is the default.  It may be
>  		disabled by writing "0" to this file, in which case all devices
>  		will be suspended and resumed synchronously.
> +
> +What:		/sys/power/wakeup_count
> +Date:		July 2010
> +Contact:	Rafael J. Wysocki <rjw@...k.pl>
> +Description:
> +		The /sys/power/wakeup_count file allows user space to avoid
> +		losing wakeup events when transitioning the system into a sleep
> +		state.  Reading from it returns the current number of registered
> +		wakeup events and it blocks if some wakeup events are being
> +		processed at the time the file is read from.  Writing to it
> +		will only succeed if the current number of wakeup events is
> +		equal to the written value and, if successful, will make the
> +		kernel abort a subsequent transition to a sleep state if any
> +		wakeup events are reported after the write has returned.

I assume that second suspend always succeeds?

I can't say I quite like the way two sysfs files interact with each
other, but it is certainly better then wakelocks...

Maybe we should create sys_suspend()?

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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