From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760666AbYBZQWv (ORCPT ); Tue, 26 Feb 2008 11:22:51 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751642AbYBZQWk (ORCPT ); Tue, 26 Feb 2008 11:22:40 -0500 Received: from cavan.codon.org.uk ([78.32.9.130]:39389 "EHLO vavatch.codon.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751012AbYBZQWj (ORCPT ); Tue, 26 Feb 2008 11:22:39 -0500 Date: Tue, 26 Feb 2008 16:21:43 +0000 From: Matthew Garrett To: Jeff Garzik Cc: Mark Lord , Pavel Machek , kernel list , Linux-pm mailing list , stern@rowland.harvard.edu, linux-ide@vger.kernel.org Message-ID: <20080226162142.GA12020@srcf.ucam.org> References: <20080225134558.GA1611@elf.ucw.cz> <47C34081.5090205@rtr.ca> <47C34472.3090706@garzik.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <47C34472.3090706@garzik.org> User-Agent: Mutt/1.5.12-2006-07-14 X-SA-Exim-Connect-IP: X-SA-Exim-Mail-From: mjg59@codon.org.uk Subject: Re: [ugly patch] Save .15W-.5W by AHCI powersaving X-SA-Exim-Version: 4.2.1 (built Tue, 20 Jun 2006 01:35:45 +0000) X-SA-Exim-Scanned: Yes (on vavatch.codon.org.uk) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Feb 25, 2008 at 05:42:58PM -0500, Jeff Garzik wrote: > BTW we can also save power by allowing the user to choose to disable > hotplugging support. Then we can power down PHYs that are not in use. > > That requires the addition of some policy controls, because it is > user-specific whether or not to waste power waiting for a plug-in event. For AHCI, if you've enabled link power management then you've already disabled hotplug. We might as well power down unused phys in that case. Note that laptop bays still seem to tend to use platform-specific hotplug notification, even when they're sata - we'll get the hotplug notify for them even if the phy's powered down, so that case also needs to be handled. -- Matthew Garrett | mjg59@srcf.ucam.org