From wookey@wookware.org Thu May 01 03:23:23 2008 Received: from [213.165.225.113] (helo=knossos.aleph1.co.uk ident=Debian-exim) by stoneboat.aleph1.co.uk with esmtps (TLS-1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.63) (envelope-from ) id 1JrORz-0000Rz-GU for balloon@balloonboard.org; Thu, 01 May 2008 03:23:23 +0100 Received: from wookey by knossos.aleph1.co.uk with local (Exim 4.63) (envelope-from ) id 1JrORm-0000mP-JN for balloon@balloonboard.org; Thu, 01 May 2008 03:22:58 +0100 Date: Thu, 1 May 2008 03:22:58 +0100 From: Wookey To: balloon@balloonboard.org Message-ID: <20080501022258.GD17242@knossos.aleph1.co.uk> Mail-Followup-To: balloon@balloonboard.org References: <00f301c8aaf5$b5034920$1f09db60$@com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <00f301c8aaf5$b5034920$1f09db60$@com> User-Agent: Mutt/1.5.13 (2006-08-11) X-Aleph_One-MailScanner: Found to be clean X-Aleph_One-MailScanner-SpamCheck: not spam, SpamAssassin (not cached, score=-2.592, required 6, autolearn=not spam, AWL 0.01, BAYES_00 -2.60, NO_RELAYS -0.00) X-Aleph_One-MailScanner-From: wookey@wookware.org X-SA-Exim-Connect-IP: 213.165.225.113 X-SA-Exim-Mail-From: wookey@wookware.org X-Spam-Checker-Version: SpamAssassin 3.2.3 (2007-08-08) on stoneboat.aleph1.co.uk X-Spam-Level: X-Spam-Status: No, score=-2.5 required=5.0 tests=AWL,BAYES_00,RDNS_NONE autolearn=no version=3.2.3 X-SA-Exim-Version: 4.2.1 (built Tue, 09 Jan 2007 17:23:22 +0000) X-SA-Exim-Scanned: Yes (on stoneboat.aleph1.co.uk) Subject: Re: [Balloon] Backup Battery, RTC and Deep sleep.... X-BeenThere: balloon@balloonboard.org X-Mailman-Version: 2.1.9 Precedence: list List-Id: Balloon List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 01 May 2008 02:23:24 -0000 On 2008-04-30 20:09 +0100, David Bisset wrote: > > Therefore to maintain the RTC registers we need the PXA to enter "Sleep" or > "Deep Sleep" modes (to reduce the current consumption to a few micro amps > provided by the backup battery), however this must be done by *software* > (not by just pulling the power) and there is a strict sequence to follow. > > {We will also need to make sure that all the other bits of the L3 board also > shut down suitably. However this should happen because nearly everything > else is powered from VCC_IO which is turned off when the system goes into > sleep/deep-sleep, but I'm sure there will be things we need to look at.} > > So I need to know how to put the PXA into deep sleep. Is this implemented in > the kernel power modes? We have basic pm support - standby and sleep (S1 and S3) (see Documenation/power/states.txt in the kernel sources). There is also some device support, but it probably not complete - e.g. the audio driver resume and suspend functions are null, and should probably be doing something like turning the audio amp on/off. > Is there a proc interface (too easy....:-)). there is a /sys interface in /sys/power/state echo /sys/power/state enmumerates the available states (we appear to only have 'mem' or 'sleep to memory - S3' appearing here) echo "mem" > /sys/power/state puts the balloon into sleep. That's as far as I've got just now as I don't know how to get it out again. I guess there is a 'reset, but not too hard' wire to wiggle somewhere? > Finally can we do voltage scaling? In principle yes - but there doesn't seem to be any obvious support for it in the pxa code (there is in strongarm). > I will configure the next rev of L3 to work both with the backup battery and > without (may need a link change) but I can't test any of this till we can > sleep the processor from software. > > Thoughts, comments welcome. I've built a kernel with power management debug and timer stats enabled and will see what works tomorrow, along with checking Nick's new udev-friendly minipug code on hardware that actually has a minipug attached. Which of the 10-odd PXA docs has best overview of PM state management? Wookey -- Principal hats: Balloonz - Toby Churchill - Aleph One - Debian http://wookware.org/