Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932995Ab1DZWG6 (ORCPT ); Tue, 26 Apr 2011 18:06:58 -0400 Received: from ksp.mff.cuni.cz ([195.113.26.206]:46427 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1756552Ab1DZWG5 (ORCPT ); Tue, 26 Apr 2011 18:06:57 -0400 Date: Wed, 27 Apr 2011 00:06:53 +0200 From: Pavel Machek To: "Rafael J. Wysocki" Cc: Greg KH , MyungJoo Ham , linux-pm@lists.linux-foundation.org, Len Brown , "Jean Delvare (PC drivers core)" , "Ben Dooks (embedded platforms)" , kyungmin.park@samsung.com, myungjoo.ham@gmail.com, LKML , Alan Stern Subject: Re: [RFC PATCH v2 1/3] PM / Core: suspend_again callback for device PM. Message-ID: <20110426220653.GA29092@elf.ucw.cz> References: <1303288106-2965-1-git-send-email-myungjoo.ham@samsung.com> <201104262249.22564.rjw@sisk.pl> <20110426211159.GB28033@elf.ucw.cz> <201104262336.56347.rjw@sisk.pl> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <201104262336.56347.rjw@sisk.pl> X-Warning: Reading this can be dangerous to your mental health. User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1714 Lines: 45 Hi! > > It certainly looks a lot like s2ram to the user. > > > > Now, your PC wakes up periodically in s2ram, too; but it is keyboard > > controller that wakes up, not CPU, so you do not know. > > I seriously doubt it's a keyboard controller in contemporary machines. > Yes, there are parts of them that don't actually sleep, but that's not > under OS control. Ok, so it is called "embedded controller" these days. But you got the idea. > > On Zaurus, you do not know, either; nothing visible happens and > > userspace is shielded from these details. > > If you wake up device drivers, it _is_ visible. Maybe not to user > space, but that's a semantic difference. Just to clarify; not _all_ device drivers need to be woken up. Just SPI + charger code is enough... and I guess it would be prefered because spinning up disk just to toggle charger would be nasty. > > Should user really have to know if battery charger is implemented on > > keyboard controller or on main cpu before he selects which interface > > to use? > > Please don't confuse user space with the user. You can resume all the > way to user space without turning the backlight on and the user will not > notice, right? The user has to type "echo mem > /sys/power/state" :-). And you better turn him the backlight on, typing blind is bad. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/