From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Garzik Subject: Re: [PATCH] ahci: Turn off DMA engines when there's no device attached Date: Wed, 24 Mar 2010 10:43:51 -0400 Message-ID: <4BAA2527.4030204@pobox.com> References: <1268253150-24050-1-git-send-email-mjg@redhat.com> <20100324141912.GA18644@srcf.ucam.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail-pz0-f194.google.com ([209.85.222.194]:53434 "EHLO mail-pz0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756400Ab0CXOnz (ORCPT ); Wed, 24 Mar 2010 10:43:55 -0400 Received: by pzk32 with SMTP id 32so943147pzk.4 for ; Wed, 24 Mar 2010 07:43:53 -0700 (PDT) In-Reply-To: <20100324141912.GA18644@srcf.ucam.org> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Matthew Garrett Cc: linux-ide@vger.kernel.org, Kristen Carlson Accardi On 03/24/2010 10:19 AM, Matthew Garrett wrote: > On Wed, Mar 10, 2010 at 03:32:30PM -0500, Matthew Garrett wrote: >> According to section 10.3.1 of the AHCI spec, PxCMD.ST must not be set >> unless there's a device attached. Following this saves us a measurable >> quantity of power and does not impair hotplug support. Based on a patch >> by Kristen Carlson Accardi. >> >> Signed-off-by: Matthew Garrett >> Cc: Kristen Carlson Accardi >> --- >> drivers/ata/ahci.c | 19 +++++++++++++++++++ >> 1 files changed, 19 insertions(+), 0 deletions(-) (please don't top-post, it makes replying more difficult) > Any feedback on this? It should be fine, but I have to rebase it onto the latest upstream ahci (libata-dev.git#upstream), so it's been waiting on that... Jeff