From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kristen Carlson Accardi Subject: Re: [patch 2/2] libata: power off unused ports Date: Fri, 28 Mar 2008 10:00:52 -0700 Message-ID: <20080328100052.70c8c55c@appleyard> References: <20080325221646.567639335@intel.com> <20080325152813.0b34761f@appleyard> <87fxubl2dv.fsf@basil.nowhere.org> Reply-To: kristen.c.accardi@intel.com Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: Received: from mga11.intel.com ([192.55.52.93]:38332 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753498AbYC1RGo (ORCPT ); Fri, 28 Mar 2008 13:06:44 -0400 In-Reply-To: <87fxubl2dv.fsf@basil.nowhere.org> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Andi Kleen Cc: jeff@garzik.org, linux-ide@vger.kernel.org, arjan@linux.intel.com On 28 Mar 2008 08:43:40 +0100 Andi Kleen wrote: > Kristen Carlson Accardi writes: > > > If a port doesn't support hot plug, there's no reason to keep the phy powered > > on unoccupied ports. > > Would it be possible to add some writable sysfs attribute for this too? > > A lot of ports support hot plug, but the users knows they will never actually > hot plug anything there. Exposing it to sysfs would make sense so > someone could make a conscious decision to save these watts by sacrifying > hotplug-support. > > -Andi > I had thought about extending the sysfs interface for link power management to include a new value: off. Right now we have min_power, medium_power, and max_performance - we could add a value for just "off" which means the port is inactive - but then we'd have to change all the sysfs stuff to check and see if the user is turning the port back on after it's been off and then re-init everything, so it might be a large effort, so if we did that I'd say it should be a separate effort from this patch series.