Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756869AbYH1W2W (ORCPT ); Thu, 28 Aug 2008 18:28:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756507AbYH1W2I (ORCPT ); Thu, 28 Aug 2008 18:28:08 -0400 Received: from moutng.kundenserver.de ([212.227.126.188]:54961 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755771AbYH1W2G convert rfc822-to-8bit (ORCPT ); Thu, 28 Aug 2008 18:28:06 -0400 From: Arnd Bergmann To: Alan Stern Subject: Re: [PATCH] usb: add Freescale QE/CPM USB peripheral controller driver Date: Fri, 29 Aug 2008 00:27:58 +0200 User-Agent: KMail/1.9.9 Cc: Scott Wood , dbrownell@users.sourceforge.net, greg@kroah.com, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org, Li Yang References: In-Reply-To: X-Face: I@=L^?./?$U,EK.)V[4*>`zSqm0>65YtkOe>TFD'!aw?7OVv#~5xd\s,[~w]-J!)|%=]>=?utf-8?q?+=0A=09=7EohchhkRGW=3F=7C6=5FqTmkd=5Ft=3FLZC=23Q-=60=2E=60Y=2Ea=5E?= =?utf-8?q?3zb?=) =?utf-8?q?+U-JVN=5DWT=25cw=23=5BYo0=267C=26bL12wWGlZi=0A=09=7EJ=3B=5Cwg?= =?utf-8?q?=3B3zRnz?=,J"CT_)=\H'1/{?SR7GDu?WIopm.HaBG=QYj"NZD_[zrM\Gip^U MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 8BIT Content-Disposition: inline Message-Id: <200808290027.59127.arnd@arndb.de> X-Provags-ID: V01U2FsdGVkX1+NSStdv0AH415ECBJbOszN7JpDHpExGuysgA4 ZrzgPXOtkDijx64oouLjEjd+lzQKLtRaqvroWd+e+vWcI1XeEu LmENyLUPv741nF9hSFRPg== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1572 Lines: 37 On Thursday 28 August 2008, Alan Stern wrote: > On Thu, 28 Aug 2008, Scott Wood wrote: > > > Alan Stern wrote: > > > This was done deliberately. ?The relevant standards state that a USB > > > device can have no more than one peripheral interface. > > > > Does building a kernel image that can run on different hardware without > > rebuilding also violate the "relevant standards"? > > No. ?That isn't what Arnd was concerned about. ?He noted that even if > you did build multiple modules, only one of them could be loaded at any > time. Well, actually it was exactly what I was concerned about ;-) The way I understand the code, it is layered into the hardware specific part and the protocol specific part, which are connected through the interfaces I pointed out. The standard requires that there can only be one protocol handler per physical interface, which is a reasonable limitation. However, what the Linux implementation actually enforces is that there can only be one hardware specific driver built or loaded into the kernel, which just looks like an arbitrary restriction that does not actually help. If the gadget hardware drivers were registering the device with a gadget_bus_type, you could still enforce the "only one protocol" rule by binding every protocol to every device in that bus type. Arnd <>< -- 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/