From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757263AbXGCOo1 (ORCPT ); Tue, 3 Jul 2007 10:44:27 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753721AbXGCOoT (ORCPT ); Tue, 3 Jul 2007 10:44:19 -0400 Received: from ogre.sisk.pl ([217.79.144.158]:45018 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753212AbXGCOoS (ORCPT ); Tue, 3 Jul 2007 10:44:18 -0400 From: "Rafael J. Wysocki" To: Johannes Berg Subject: Re: [linux-pm] Re: [PATCH] Remove process freezer from suspend to RAM pathway Date: Tue, 3 Jul 2007 16:51:09 +0200 User-Agent: KMail/1.9.5 Cc: Benjamin Herrenschmidt , Matthew Garrett , linux-kernel@vger.kernel.org, Pavel Machek , linux-pm@lists.linux-foundation.org References: <20070703042916.GA17240@srcf.ucam.org> <200707031456.40890.rjw@sisk.pl> <1183472474.3722.13.camel@johannes.berg> In-Reply-To: <1183472474.3722.13.camel@johannes.berg> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-15" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200707031651.10225.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday, 3 July 2007 16:21, Johannes Berg wrote: > On Tue, 2007-07-03 at 14:56 +0200, Rafael J. Wysocki wrote: > > > Still, can you please read this post from Alan Stern: > > > > https://lists.linux-foundation.org/pipermail/linux-pm/2007-June/012847.html > > > > ? I don't think I'm able to repeat the arguments given in there in a > > convincing way. > > As I read it, Alan basically has two objections: > (1) drivers shouldn't need to worry about this > (2) suspend should be transparent to userspace > > His proposed solution (freezing tasks when they cross the kernel > boundary) helps for the s-t-r case, but in fact doesn't solve (1) > because devices can be suspended at runtime This is a different thing and a different infrastructure is needed for it (not present at the moment). > and then you certainly do not want to freeze tasks that try to access the > device. > > (2) is related but not identical, what if you have a device suspended at > runtime and some tasks tries to access it; should the task block until > you wake up that device? I think the device should be woken up in that case. > I think the core of the discussion isn't appreciated by everybody here > yet---we need to solve both run-time and suspend-to-ram-time device > suspend, not just one of them. For now, we're discussing the suspend-to-ram-time suspend only, for which we have (some) infrastrcuture (and which should be supported by all drivers, IMO). Greetings, Rafael -- "Premature optimization is the root of all evil." - Donald Knuth