From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alan Stern Subject: Re: [RFC][PATCH 00/11] Android PM extensions Date: Mon, 2 Feb 2009 10:09:38 -0500 (EST) Message-ID: References: <200902021200.59992.u.luckas@road.de> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <200902021200.59992.u.luckas@road.de> 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: Uli Luckas Cc: Brian Swetland , linux-pm@lists.linux-foundation.org, Nigel Cunningham List-Id: linux-pm@vger.kernel.org On Mon, 2 Feb 2009, Uli Luckas wrote: > On Sunday, 1. February 2009, Alan Stern wrote: > > Early-suspend seems to be a completely different matter. =A0In fact it > > isn't a suspend state at all, as far as I understand it. =A0It's more > > like what you get simply by doing a runtime suspend on some collection > > of devices. =A0I don't see that the kernel needs to treat it as a speci= al > > state, and in might be possible to have a user program manage the whole > > thing -- provided the drivers in question implement runtime power > > management (as USB has done). > > > > Alan Stern > = > Except you always want early-suspend and auto-suspend at the same time. T= he = > idea is, if all display of system states is off (early-suspend), we can = > enable or disable the cpu at will (auto-suspend) because nobody will noti= ce. = Why should the kernel have to get involved? Why can't userspace manage = both early-suspend and auto-suspend? That is, consider the following: Userspace initiates an early-suspend by using a runtime PM interface to turn off the screen and some other devices. After a short time, if they are still off, then userspace can initiate an auto-suspend by writing "auto-mem" to /sys/power/state. All the kernel would need to know is the difference between auto-suspend and normal suspend: one respects wakelocks and the other doesn't. Alan Stern