Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751355AbWIXUSH (ORCPT ); Sun, 24 Sep 2006 16:18:07 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751519AbWIXUSH (ORCPT ); Sun, 24 Sep 2006 16:18:07 -0400 Received: from achilles.noc.ntua.gr ([147.102.222.210]:28629 "EHLO achilles.noc.ntua.gr") by vger.kernel.org with ESMTP id S1751355AbWIXUSF (ORCPT ); Sun, 24 Sep 2006 16:18:05 -0400 Date: Sun, 24 Sep 2006 15:18:18 +0300 (EEST) From: "Theodoros V. Kalamatianos" To: Pavel Machek cc: kernel list , Greg KH , Linux usb mailing list Subject: Re: [linux-usb-devel] usb still sucks battery in -rc7-mm1 In-Reply-To: <20060924090858.GA1852@elf.ucw.cz> Message-ID: References: <20060924090858.GA1852@elf.ucw.cz> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1512 Lines: 37 On Sun, 24 Sep 2006, Pavel Machek wrote: > 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 ? Regards, Theodoros Kalamatianos 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. - 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/