From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Rafael J. Wysocki" Subject: Re: Re: [PATCH] Remove process freezer from suspend to RAM pathway Date: Tue, 3 Jul 2007 16:51:09 +0200 Message-ID: <200707031651.10225.rjw@sisk.pl> References: <20070703042916.GA17240@srcf.ucam.org> <200707031456.40890.rjw@sisk.pl> <1183472474.3722.13.camel@johannes.berg> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-15" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1183472474.3722.13.camel@johannes.berg> Content-Disposition: inline List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-pm-bounces@lists.linux-foundation.org Errors-To: linux-pm-bounces@lists.linux-foundation.org To: Johannes Berg Cc: linux-pm@lists.linux-foundation.org, linux-kernel@vger.kernel.org, Pavel Machek , Matthew Garrett List-Id: linux-pm@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