Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752030Ab1CKRIL (ORCPT ); Fri, 11 Mar 2011 12:08:11 -0500 Received: from opensource.wolfsonmicro.com ([80.75.67.52]:56953 "EHLO opensource2.wolfsonmicro.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751606Ab1CKRIK (ORCPT ); Fri, 11 Mar 2011 12:08:10 -0500 Date: Fri, 11 Mar 2011 17:08:07 +0000 From: Mark Brown To: Greg KH Cc: Arnd Bergmann , andy.green@linaro.org, Linux USB list , lkml Subject: Re: RFC: Platform data for onboard USB assets Message-ID: <20110311170807.GV1760@opensource.wolfsonmicro.com> References: <4D79F068.2080009@linaro.org> <201103111331.13932.arnd@arndb.de> <20110311152938.GB29920@sirena.org.uk> <201103111654.04089.arnd@arndb.de> <20110311160308.GQ1760@opensource.wolfsonmicro.com> <20110311161421.GA7843@kroah.com> <20110311162759.GS1760@opensource.wolfsonmicro.com> <20110311163522.GA9291@kroah.com> <20110311164850.GT1760@opensource.wolfsonmicro.com> <20110311165642.GA9996@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110311165642.GA9996@kroah.com> X-Cookie: You will contract a rare disease. User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1761 Lines: 35 On Fri, Mar 11, 2011 at 08:56:42AM -0800, Greg KH wrote: > On Fri, Mar 11, 2011 at 04:48:50PM +0000, Mark Brown wrote: > > USB itself is discoverable but the when the USB bus you're looking at is > > one that's soldered down onto a board in a specific design all bets are > > off regarding how complete the information you get will be. On a basic > > level the designers may have done things like omit the configuration > > EEPROMs that would set the device IDs that the driver should be relying > > on to identify the hardware configuration. There may be other, nastier, > > things going on. > Then you use the existing platform data for your USB host controller > driver. Doesn't that work today just fine? Wrong end of the bus. This stuff is simple enough to deal with in a system specific fashion, the standard solution would be to patch the relevant drivers to hard code whatever is required. > > You really can't make this assumption about discoverable buses on > > embedded devices. The discoverability will get you most of the way > > there but not always all of the way there. > Then the bus is not really USB, sorry. USB is discoverable, _and_ can > support enumeration in non-deterministic ways. If people are using it > in other ways then it is not USB and is something else. That's certainly a valid way of looking at things but it doesn't really move mainline support for systems which do stuff like this forward. On the bright side I don't generally have to work on this stuff myself :) -- 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/