From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pavel Machek Subject: Re: So, what's the status on the recent patches here? Date: Thu, 31 Aug 2006 14:04:54 +0200 Message-ID: <20060831120454.GS3923@elf.ucw.cz> References: <20060830225057.GG3923@elf.ucw.cz> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Return-path: Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-pm-bounces@lists.osdl.org Errors-To: linux-pm-bounces@lists.osdl.org To: Preece Scott-PREECE Cc: Matthew Locke , linux-pm@lists.osdl.org List-Id: linux-pm@vger.kernel.org Hi! > > We may have confusion here. > > = > > On PC, it is definitely not possible to enter sleep state = > > between frames of video... because video is powered off. > > = > > On PC, sleep states are *system* sleep states. CPU sleep = > > states exist, too, but that's in-kernel implementation = > > detail. They are called C1..C4. > --- > = > Well, we have some hardware where we can sleep everything but = > memory and some where we can also leave the display active (and = > backlit). In fact, however, today the latency for going to sleep = > is too great to do so between frames, so we just do a wait there. = > We would LIKE to be able to sleep there at some point in the = > future and would prefer a power model that made that cleanly = > part of a continuum of operating points. > = > However, we definitely DO sleep (with self-refreshing RAM) during = > relatively short periods, with the wakeup resulting from an = > interrupt from the RTC (which is self-powered and is set = > to timeout at the next scheduled timer when we go to sleep) = > or another hardware interrupt. We think of this as a system-level = > sleep state. > = > I'm not sure how you distinguish between a "system" sleep state = > and a "CPU" sleep state - seems like there's a collection of = > things that can be shut down or not; except for true OFF, there's > always something on. Well, even in "true OFF", RTC keeps ticking. And in "disk" state (swsusp), machine is basically "true OFF" but it still retains state. Pavel -- = (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blo= g.html