Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751520AbWIXUUj (ORCPT ); Sun, 24 Sep 2006 16:20:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751535AbWIXUUi (ORCPT ); Sun, 24 Sep 2006 16:20:38 -0400 Received: from gprs189-60.eurotel.cz ([160.218.189.60]:28588 "EHLO amd.ucw.cz") by vger.kernel.org with ESMTP id S1751528AbWIXUUi (ORCPT ); Sun, 24 Sep 2006 16:20:38 -0400 Date: Sun, 24 Sep 2006 22:20:25 +0200 From: Pavel Machek To: "Theodoros V. Kalamatianos" Cc: kernel list , Greg KH , Linux usb mailing list Subject: Re: [linux-usb-devel] usb still sucks battery in -rc7-mm1 Message-ID: <20060924202025.GE1873@elf.ucw.cz> References: <20060924090858.GA1852@elf.ucw.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Warning: Reading this can be dangerous to your mental health. User-Agent: Mutt/1.5.11+cvs20060126 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1815 Lines: 39 Hi! > >I made some quick experiments, and usb still eats 4W of battery > >power. (With whole machine eating 9W, that's kind of a big deal)... > > > >This particular machine has usb bluetooth, but it can be disabled by > >firmware, and appears unplugged. (I did that). It also has fingerprint > >scanner, that can't be disabled, but that does not have driver (only > >driven by useland, and was unused in this experiment). > > > >Any ideas? > > (I have not followed the thread, so bear with me if I say anything > irrelavant) > > I have encountered at least 3 hubs (2 usb2 & 1 usb1) that will consume a > lot of power (about 2-2.5W if the laptop power consumption readings are to > be trusted) and heat up a lot (to the point of being too hot to touch for > more than a few seconds) even when no devices are connected, at least on > Linux. I have not tested them on a Windows machine to see if this is the > case there. The USB2 ones used Cypress chips. I do not know what your h/w > config is, but perhaps this is a similar case ? > PS: Note that the 2-2.5W consumption is the maximum that the laptop USB > port can provide, and I have noticed that with the hub's external power > supply connected it heats up even more. I'm not using any external hubs. I believe it is old "uhci keeps cpu from reaching deep c states" problem. I just want to ping greg/list, because greg told me problem is solved in -mm. 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/