From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754481AbYI3BG0 (ORCPT ); Mon, 29 Sep 2008 21:06:26 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753179AbYI3BGR (ORCPT ); Mon, 29 Sep 2008 21:06:17 -0400 Received: from cavan.codon.org.uk ([93.93.128.6]:47862 "EHLO vavatch.codon.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752380AbYI3BGR (ORCPT ); Mon, 29 Sep 2008 21:06:17 -0400 Date: Tue, 30 Sep 2008 02:06:13 +0100 From: Matthew Garrett To: "Jeffrey W. Baker" Cc: linux-kernel@vger.kernel.org Subject: Re: Put unused PCI devices in D3 Message-ID: <20080930010613.GA30375@srcf.ucam.org> References: <1222719064.19236.129.camel@squeak.gghcwest.com> <20080930000923.GA29775@srcf.ucam.org> <1222736147.21516.12.camel@stinkpad> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1222736147.21516.12.camel@stinkpad> User-Agent: Mutt/1.5.12-2006-07-14 X-SA-Exim-Connect-IP: X-SA-Exim-Mail-From: mjg59@codon.org.uk X-SA-Exim-Scanned: No (on vavatch.codon.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Sep 29, 2008 at 05:55:47PM -0700, Jeffrey W. Baker wrote: > No, you couldn't, but that isn't really the point. If I have my laptop > on a transoceanic flight it may be useful for me to be able to set a > power policy turning off all the extraneous junk on my machine, because > I know /a priori/ that no hotplug events will happen. There's no way > the kernel could know that, but userspace can tell the kernel to turn > off an unneeded device. The majority (though it's not universal) of modern hardware can be put into a state where you get most of the power savings of the entire part being in D3 but with little functional regression. While I'm not averse to adding features that aid the power user who's happy to poke around with individual drivers, this shouldn't be at the expense of implementing good runtime power management for the more common case. Not that I'm suggesting you're doing that, I just want to emphasise that you're working on a slightly more niche concern :) -- Matthew Garrett | mjg59@srcf.ucam.org