From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758165Ab1DZUst (ORCPT ); Tue, 26 Apr 2011 16:48:49 -0400 Received: from ogre.sisk.pl ([217.79.144.158]:53909 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753389Ab1DZUss (ORCPT ); Tue, 26 Apr 2011 16:48:48 -0400 From: "Rafael J. Wysocki" To: Pavel Machek Subject: Re: [RFC PATCH v2 1/3] PM / Core: suspend_again callback for device PM. Date: Tue, 26 Apr 2011 22:49:22 +0200 User-Agent: KMail/1.13.6 (Linux/2.6.39-rc4+; KDE/4.6.0; x86_64; ; ) Cc: Greg KH , MyungJoo Ham , linux-pm@lists.linux-foundation.org, Len Brown , "Jean Delvare (PC drivers core)" , "Ben Dooks (embedded platforms)" , kyungmin.park@samsung.com, myungjoo.ham@gmail.com, LKML , Alan Stern References: <1303288106-2965-1-git-send-email-myungjoo.ham@samsung.com> <20110426131737.GA13597@suse.de> <20110426203853.GC27140@elf.ucw.cz> In-Reply-To: <20110426203853.GC27140@elf.ucw.cz> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201104262249.22564.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday, April 26, 2011, Pavel Machek wrote: > Hi! > > > > To conclude, I'm not sure about the approach. In particular, I'm not sure > > > if the benefit is worth the effort and the resulting complications (ie. the > > > possibility of having to deal with wakeup signals not requested by user > > > space) seem to be a bit too far reaching. > > > > > > Greg, what do you think? > > > > I agree with you in that I don't think that this type of feature is > > valid at the moment. > > Our current "solution" is low level suspend code on Zaurus directly > looking at charger state and doing the "wakeup or not" decision by hand. > > > I don't understand why our current situation doesn't work, what are we > > lacking that is needed for these systems that we have not seen > > before? > > It works, but it is ugly; and it seems samsung now needs similar > hacks. > > > What is the root problem that this is trying to solve? > > It is trying to fix machines that need to run periodic kernel tasks > even when user asked them to sleep. Zaurus needs to periodicaly wake > up to be able to charge battery in s2ram state, for example. Well, if you wake up periodically, it's not S2RAM any more, I'd say. Thanks, Rafael