From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pavel Machek Subject: Re: [RFC][PATCH 00/11] Android PM extensions Date: Mon, 2 Feb 2009 12:55:18 +0100 Message-ID: <20090202115518.GA4609@elf.ucw.cz> References: <200901311939.30837.rjw@sisk.pl> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <200901311939.30837.rjw@sisk.pl> 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: "Rafael J. Wysocki" Cc: Brian Swetland , linux-pm@lists.linux-foundation.org, Nigel Cunningham List-Id: linux-pm@vger.kernel.org Hi! > However, I think that what we are used to call a sleep (or suspend) state is > really a power off state for cell phone people. So lets define what we're > talking about. > > Sleep states (suspend to RAM, hibernation) are the states of the whole system > in which no instructions are executed by the processor(s). The > difference s/processor(s)/CPU/. Even in PC, you have keyboard controller running while sleeping. On cellphone, you have some kind of pmu chip + GSM chip running. So cellphone actually _is_ useful even when CPU is sleeping. > between a sleep state and the power off state is that in a sleep state we have > some application context saved (in memory or in a storage device) and > (in principle) after the system goes back to the working state, the > applications can continue doing do whatever they had been doing before the > system was put into the sleep state. > > If instructions are executed by the processor(s), the system is in the working > state. ACK. > Well, I think that sleep states are not really useful in cell phones. Useful > is the ability to put all devices into low power states separately and as > needed (eg. after a period of inactivity). IOW, the system as a > whole is No, it does not work like that. Cellphone with sleeping CPU (suspended-to-RAM) is still very useful. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html