Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932203Ab0F3SAr (ORCPT ); Wed, 30 Jun 2010 14:00:47 -0400 Received: from iolanthe.rowland.org ([192.131.102.54]:39187 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1755810Ab0F3SAq (ORCPT ); Wed, 30 Jun 2010 14:00:46 -0400 Date: Wed, 30 Jun 2010 14:00:41 -0400 (EDT) From: Alan Stern X-X-Sender: stern@iolanthe.rowland.org To: "Rafael J. Wysocki" cc: linux-pm@lists.linux-foundation.org, Linux Kernel Mailing List , Neil Brown , Matthew Garrett , mark gross <640e9920@gmail.com>, Arve =?iso-8859-1?q?Hj=F8nnev=E5g?= , Dmitry Torokhov , Florian Mickler , , Jesse Barnes Subject: Re: [update] Re: [PATCH] PM: Make it possible to avoid wakeup events from being lost In-Reply-To: <201006282101.54041.rjw@sisk.pl> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1983 Lines: 39 On Mon, 28 Jun 2010, Rafael J. Wysocki wrote: > +/* > + * The functions below use the observation that each wakeup event starts a > + * period in which the system should not be suspended. The moment this period > + * will end depends on how the wakeup event is going to be processed after being > + * detected and all of the possible cases can be divided into two distinct > + * groups. > + * > + * First, a wakeup event may be detected by the same functional unit that will > + * carry out the entire processing of it and possibly will pass it to user space > + * for further processing. In that case the functional unit that has detected > + * the event may later "close" the "no suspend" period associated with it > + * directly as soon as it has been dealt with. The pair of pm_stay_awake() and > + * pm_relax(), balanced with each other, is supposed to be used in such > + * situations. > + * > + * Second, a wakeup event may be detected by one functional unit and processed > + * by another one. In that case the unit that has detected it cannot really > + * "close" the "no suspend" period associated with it, unless it knows in > + * advance what's going to happen to the event during processing. This > + * knowledge, however, may not be available to it, so it can simply specify time > + * to wait before the system can be suspended and pass it as the second > + * argument of pm_wakeup_event(). > + */ Since there's no longer any way to cancel a call to pm_wakeup_event() or close the "no suspend" period early, there is no need to use dynamically-allocated delayed_work structures. You can make do with a single static timer; always keep it set to expire at the latest time passed to pm_wakeup_event(). Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/