Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757659Ab1EaTH2 (ORCPT ); Tue, 31 May 2011 15:07:28 -0400 Received: from iolanthe.rowland.org ([192.131.102.54]:52960 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1754480Ab1EaTH1 (ORCPT ); Tue, 31 May 2011 15:07:27 -0400 Date: Tue, 31 May 2011 15:07:24 -0400 (EDT) From: Alan Stern X-X-Sender: stern@iolanthe.rowland.org To: Brokhman Tatyana cc: greg@kroah.com, , , , , open list Subject: Re: [PATCH v14 9/9] usb: Adding SuperSpeed support to dummy_hcd In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1784 Lines: 44 On Tue, 31 May 2011, Brokhman Tatyana wrote: > Hi Alan, > > > If is_super_speed is false, shouldn't you avoid registering the > > SuperSpeed hub? Or would that add too many complications? > > It woun't add too many complications but I would prefere not to do that. > My goal was to simulate as much as posible "real" USB connection so the > is_super_speed flag simulates the USB port you connect to, HS/SS. The terms "HS port" and "SS port" don't really mean anything. A physical port connected to a USB-3 controller will run at either HS or SS depending on the cable and device plugged into it. > When > working with a real host if you connect a HS device to a SS port it > connects to a HS root hub but the SS root hub is functional and > registered. The correct way to express this is: If you connect a HS device to a USB-3 controller then it connects to the HS root hub, but the SS root hub is functional and present. That's true, but it misses the point of my question. Does the "is_super_speed" module parameter refer to dummy-hcd's emulated _host_ controller or to the emulated _device_ controller? (Or does it perhaps refer to both?) If it refers to the emulated host controller then there should be no SS root hub. But if it refers only to the emulated device controller then there should be. Let's put it another way. If the "is_super_speed" module parameter is set to False then we know that the emulated connection will never run at SS. Therefore there's no point in registering a SS root hub. Alan Stern -- 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/