From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753337AbZEUMIi (ORCPT ); Thu, 21 May 2009 08:08:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752989AbZEUMIb (ORCPT ); Thu, 21 May 2009 08:08:31 -0400 Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:60410 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752958AbZEUMIa (ORCPT ); Thu, 21 May 2009 08:08:30 -0400 Date: Thu, 21 May 2009 14:08:25 +0200 From: Pavel Machek To: =?iso-8859-1?Q?=C9ric?= Piel Cc: Andrew Morton , LKML Subject: Re: [PATCH 2/4] lis3: remove automatic shutdown of the device Message-ID: <20090521120825.GH2637@elf.ucw.cz> References: <4A151E9F.1080405@tremplin-utc.net> <4A151F52.3050908@tremplin-utc.net> <20090521113618.GF2637@elf.ucw.cz> <4A15411F.3050704@tremplin-utc.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4A15411F.3050704@tremplin-utc.net> X-Warning: Reading this can be dangerous to your mental health. User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi! > >> After measurement on my laptop, it seems that turning off the device > >> does not bring any energy saving (within 0.1W precision). So let's keep > >> the device always on. It simplifies the code, and it avoids the problem > >> of reading a wrong value sometimes just after turning the device on. > > > > Well, 0.1W is still quite much for cellphone etc... but as we do not > > have any such small users in the tree, I guess this can go in... > > > Yes. BTW, what I meant is that the power consumption on my laptop can be > read with 0.1W precision. Turning on and off the device showed 0.0W > variations. The device should using even much less than 0.1W. According > to the documentation, it's about 2.2mW when on and 3?W when off. 2mW would be still significant on a cellphone, draining battery in cca 20 days (which is about as bad as GSM radio), but... If cellphone user comes, he can simply recreate powersaving code... Feel free to add Signed-off-by: Pavel Machek to 2,3/4. ... And btw 4/4 probably could be pushed to 2.6.30. It is trivial enough... and "new hw" support is okay even late in cycle. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html