From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932525AbZLDXee (ORCPT ); Fri, 4 Dec 2009 18:34:34 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757471AbZLDXed (ORCPT ); Fri, 4 Dec 2009 18:34:33 -0500 Received: from outbound-mail-15.bluehost.com ([69.89.18.115]:60664 "HELO outbound-mail-15.bluehost.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1757410AbZLDXec convert rfc822-to-8bit (ORCPT ); Fri, 4 Dec 2009 18:34:32 -0500 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=default; d=virtuousgeek.org; h=Received:Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References:X-Mailer:Mime-Version:Content-Type:Content-Transfer-Encoding:X-Identified-User; b=mCX+2f24end3tAFs7sLdbOE+lQhDMAU6KBGrdMkNXodwSJCC94m/GNOz9feXZHGmUHO/seVaSv6sOeInpnN2JPpdU0XDGzmNMrZsZGMN4AWxE0GTZxh4+MJ8hJB8543f; Date: Fri, 4 Dec 2009 15:33:51 -0800 From: Jesse Barnes To: "Stephane GONAUER" Cc: , , , , Subject: Re: PCIexpress Slot_Power_Limit and Power budgetting. Message-ID: <20091204153351.3752feea@jbarnes-piketon> In-Reply-To: <001401ca6901$f9c03ed0$ed40bc70$@gonauer@sofrelog.com> References: <001401ca6901$f9c03ed0$ed40bc70$@gonauer@sofrelog.com> X-Mailer: Claws Mail 3.7.2 (GTK+ 2.18.3; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT X-Identified-User: {10642:box514.bluehost.com:virtuous:virtuousgeek.org} {sentby:smtp auth 75.111.28.251 authed with jbarnes@virtuousgeek.org} Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 19 Nov 2009 11:20:50 +0100 "Stephane GONAUER" wrote: > I am a embedded system designer and currently working on the > preliminary design of a PCIepress expansion board to be used on x86 > motherboard. > > My board is to be an x1 PCie board. Thus according to the PCIe > electromechanical specifications, the board may consume 10Watts by > default, and 25Watts after correct dialog is established with upper > bridges and the root complex. (which after acknowledging the request > should send a Slot_Power_Limit message to the board to allow for > higher power consumption). > > The board is based on a PEX8311 PCIe to local bus chip from PLX tech. > This component is able to present its request for more power using > the power budgeting capability as defined by the PCIe standard. > > However this doesn’t seems to have effect on the system (running > latest ubuntu with 2.6.31 kernel) and from my understanding of the > kernel sources this is not supported. Is that correct ? > > Are there ways that I’m not aware to request for more power in the > existing source base ? Not in PCIe that I'm aware of, aside from the existing ASPM support, but that's a bit different. > I’ve been reading the PCIE-port driver source to try to find a way to > achieve my goal. My understanding is that this driver is very generic > and as such shouldn’t be able to support power budgeting. I believe > adding Power budgeting to it would require to match more closely the > motherboard hardware. Am I correct ? Yeah, we'd need to get power budget info from the firmware or platform somehow, which means we'd have to add a platform specific portion to the PCIe port driver, or at the very least some basic power initialization routines that could be called from platform specific code. > Perhaps you have better ideas on the subject than me. > > I’d be very glad if I could get some comments on this issue. I hope I > haven’t been writing to the wrong people. Given how long it's taken me to reply, maybe you have an implementation already. :) We'd definitely be interested in adding such a feature if your platform supports it and has need of it. -- Jesse Barnes, Intel Open Source Technology Center