From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Hutchings Subject: Re: Linux support for 802.3af? Date: Sat, 13 Mar 2010 04:40:03 +0000 Message-ID: <1268455203.7439.78.camel@localhost> References: <4B9AD5CA.7000303@redfish-solutions.com> <1268440985.7439.23.camel@localhost> <4B9AE62B.6050502@redfish-solutions.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org To: "Philip A. Prindeville" Return-path: Received: from mail.solarflare.com ([216.237.3.220]:3803 "EHLO exchange.solarflare.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754720Ab0CMEkI (ORCPT ); Fri, 12 Mar 2010 23:40:08 -0500 In-Reply-To: <4B9AE62B.6050502@redfish-solutions.com> Sender: netdev-owner@vger.kernel.org List-ID: On Fri, 2010-03-12 at 18:11 -0700, Philip A. Prindeville wrote: > On 03/12/2010 05:43 PM, Ben Hutchings wrote: > > On Fri, 2010-03-12 at 17:01 -0700, Philip A. Prindeville wrote: > >> I was looking at this Marvell-based 4-port PCI card with PoE and > >> thinking it would be handy for powering cameras and ip-phones, but don't > >> remember seeing any kernel support for 802.3af... > >> > >> http://www.korenix.com/jetcard-PoE_Universal_PCI_Card-2215-overview.htm > >> > >> There's no support for 802.3af, right? > > > > The standard MDIO ioctls can be used to access registers 11 and 12 on > > PHYs with integrated PSE functionality. There is no way of indicating > > whether a PHY has such functionality, but a flag for this could be added > > to the mdio_support field of struct ethtool_cmd. > > > > Ben. > > Well, there's more to it than that, right? > > There's a software state machine that's required to go through the > handshake, there's prioritization and power budgeting, etc. Yes? > > What am I missing? We seem to have contrary expectations of how a PSE would be implemented. You assume that the CPU would be involved at quite a low level. I assume that a PSE in a Linux system would be implemented on a peripheral device and that it would be managed from the host via MDIO (though this is specified as an optional feature). Looking at the specs, that particular card is using a Marvell switch chip which doesn't have any PoE support, so management via MDIO seems unlikely. If you're curious I suppose you should try to get the driver from this vendor. Ben. -- Ben Hutchings, Senior Software Engineer, Solarflare Communications Not speaking for my employer; that's the marketing department's job. They asked us to note that Solarflare product names are trademarked.