Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757400AbYACRI4 (ORCPT ); Thu, 3 Jan 2008 12:08:56 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752927AbYACRIs (ORCPT ); Thu, 3 Jan 2008 12:08:48 -0500 Received: from outbound-mail-12.bluehost.com ([69.89.18.112]:35882 "HELO outbound-mail-12.bluehost.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1753022AbYACRIr (ORCPT ); Thu, 3 Jan 2008 12:08:47 -0500 X-Greylist: delayed 399 seconds by postgrey-1.27 at vger.kernel.org; Thu, 03 Jan 2008 12:08:47 EST From: "Richard D" To: "'Alan Stern'" , "'David Brownell'" Cc: "'Mike Frysinger'" , , , "'Robin Getz'" , References: <200801021225.28370.david-b@pacbell.net> In-Reply-To: Subject: RE: [linux-usb-devel] [PATCH] : Allow embedded developers USB options normally reserved for OTG Date: Thu, 3 Jan 2008 22:31:54 +0530 Message-ID: <001b01c84e2a$60558730$21009590$@com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Mailer: Microsoft Office Outlook 12.0 Thread-Index: AchNgwDTSU/J9nGuQRe+GG9JFKtNlwApsNxg Content-Language: en-us X-Identified-User: {2260:host187.hostmonster.com:embunusc:embunus.com} {sentby:bopbeforesmtp 121.247.188.187 authed with embunus.com} Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2148 Lines: 53 > -----Original Message----- > From: linux-kernel-owner@vger.kernel.org [mailto:linux-kernel- > owner@vger.kernel.org] On Behalf Of Alan Stern > Sent: Thursday, January 03, 2008 2:29 AM > To: David Brownell > Cc: Mike Frysinger; gregkh@suse.de; linux-usb- > devel@lists.sourceforge.net; Robin Getz; linux-kernel@vger.kernel.org > Subject: Re: [linux-usb-devel] [PATCH] : Allow embedded developers USB > options normally reserved for OTG > > On Wed, 2 Jan 2008, David Brownell wrote: > > > On Wednesday 02 January 2008, Alan Stern wrote: > > > On Wed, 2 Jan 2008, Mike Frysinger wrote: > > > > > > > perhaps the code size is arguable as to whether it really > matters. > > > > the reason we want it is that we have a USB host controller that > will > > > > not work with USB hubs, so we want to make sure the system does > not > > > > attempt such things. (yes, such a USB host controller is > retarded, > > > > but the decision was out of our hands.) > > > > > > Just out of curiosity, how does a host controller manage to avoid > > > working with external hubs? > > > > The transaction translators in external high speed hubs require > > hosts to issue particular USB transactions. If the host controller > > doesn't implement the that split transaction support, then it won't > > be supporting external hubs. > > So in theory one could connect a high-speed hub to such a host > controller and expect it to communicate with high-speed devices. So > long as no full- or low-speed devices are added there wouldn't be any > split transactions. It wouldn't be USB-2.0 compliant but it should > still work. Perhaps we could reject any low/full speed devices after the USBV enumeration phase itself. This would need perhaps a flag in the struct hc_driver which the hub code (that does the enumeration) can check and reject further enumeration? Atleast this way we can support high speed devices. -- 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/