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Date: Fri, 27 Feb 2009 14:29:46 +0000
From: Matthew Garrett <mjg59@srcf.ucam.org>
To: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Pavel Machek <pavel@ucw.cz>, Arve Hj?nnev?g <arve@android.com>,
       Alan Stern <stern@rowland.harvard.edu>,
       "Woodruff, Richard" <r-woodruff2@ti.com>,
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       Igor Stoppa <igor.stoppa@nokia.com>,
       Brian Swetland <swetland@google.com>, Len Brown <lenb@kernel.org>
Subject: Re: [RFD] Automatic suspend
Message-ID: <20090227142946.GA13650@srcf.ucam.org>
References: <200902192215.18365.rjw@sisk.pl> <200902210057.27781.rjw@sisk.pl> <20090227100941.GE4582@elf.ucw.cz> <200902271522.41915.rjw@sisk.pl>
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On Fri, Feb 27, 2009 at 03:22:39PM +0100, Rafael J. Wysocki wrote:
> On Friday 27 February 2009, Pavel Machek wrote:
> > Wakelocks done right are single atomic_t... and if you set it to 0,
> > you just unblock "sleeper" thread or something. Zero polling and very
> > simple...
> 
> Except that you have to check all of the wakelocks periodically in a loop =>
> polling.  So?

Why do you need to check them? If you're taking this approach you just 
have something like:

suspend_unblock() {
	if (atomc_dec_and_test(&suspend_lock))
		suspend();
}

and then check that the lock count is still 0 after device_suspend(). 
There's no need to poll.

-- 
Matthew Garrett | mjg59@srcf.ucam.org