Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755893Ab1CQVsB (ORCPT ); Thu, 17 Mar 2011 17:48:01 -0400 Received: from kroah.org ([198.145.64.141]:50088 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755870Ab1CQVr7 (ORCPT ); Thu, 17 Mar 2011 17:47:59 -0400 Date: Thu, 17 Mar 2011 14:47:36 -0700 From: Greg KH To: Mark Brown Cc: Nicolas Pitre , Arnd Bergmann , andy.green@linaro.org, Linux USB list , lkml Subject: Re: RFC: Platform data for onboard USB assets Message-ID: <20110317214736.GA29014@kroah.com> References: <20110311165642.GA9996@kroah.com> <20110311170807.GV1760@opensource.wolfsonmicro.com> <20110311172345.GA10876@kroah.com> <20110317201320.GB4035@kroah.com> <20110317201835.GM31411@opensource.wolfsonmicro.com> <20110317202614.GA3155@kroah.com> <20110317212449.GO31411@opensource.wolfsonmicro.com> <20110317213108.GA16065@kroah.com> <20110317214042.GQ31411@opensource.wolfsonmicro.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110317214042.GQ31411@opensource.wolfsonmicro.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2267 Lines: 48 On Thu, Mar 17, 2011 at 09:40:42PM +0000, Mark Brown wrote: > On Thu, Mar 17, 2011 at 02:31:08PM -0700, Greg KH wrote: > > On Thu, Mar 17, 2011 at 09:24:49PM +0000, Mark Brown wrote: > > > > The way this is normally done is that the ethernet controller can be > > > attached to a SEPROM which it reads when it powers on. This will > > > contain a number of device configuration parameters, including the > > > vendor IDs and the MAC address, which will be configured before the > > > device makes itself available on the bus. If the system integrator has > > > omitted the SEPROM then the device will come up with defaults, usually > > > something like all zeros. > > > Ok, then again, let's deal with this on a case-by-case basis please, as > > this is going to be a "rare" thing in the real world. I don't want to > > encourage _any_ engineers to think that this is ok to do for USB > > devices. > > It's really not at all rare in the embedded world - the overwhelming > majority of the systems I've worked on have omitted the SEPROMS for > components that are soldered down in the system. It'd be pretty insane > to do it for things that are distinct USB devices but that's not the > case. > > There are good solid engineering reasons for doing things this way if > you've got any prospect of shifting any kind of volume, as well as the > cost saving achieved by removing a component you also simplify and most > likely speed up the production process as you can reduce the number of > components that need to be programmed on each system that gets built. > > > Patches to fix this, for this specific PandaBoard controller are gladly > > accepted. What's odd is this is explicitly a Linux development board, > > so you would think that this could have been caught, and fixed, in the > > hardware a long time ago, right? > > The way everyone resolves this stuff is by patching their kernel > locally. Well, that means that the device tree work is going to be useful here, right? :) Best of luck, greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/