Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757540AbYC0C6t (ORCPT ); Wed, 26 Mar 2008 22:58:49 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755205AbYC0C6j (ORCPT ); Wed, 26 Mar 2008 22:58:39 -0400 Received: from netrider.rowland.org ([192.131.102.5]:1055 "HELO netrider.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1754966AbYC0C6i (ORCPT ); Wed, 26 Mar 2008 22:58:38 -0400 Date: Wed, 26 Mar 2008 22:58:37 -0400 (EDT) From: Alan Stern X-X-Sender: stern@netrider.rowland.org To: Greg KH cc: mark gross , lkml , , Subject: Re: Real time USB2Serial devices and behaivor In-Reply-To: <20080326232419.GC15468@kroah.com> 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: 936 Lines: 24 On Wed, 26 Mar 2008, Greg KH wrote: > > Is there any reason to think that if I created my own isochronous > > USB2Serial adapter and iso-usb-driver that I couldn't get determinism? > > I strongly doubt it as others have tried and failed in the past. I don't understand. Isochronous transfers have pretty strict transfer-time guarantees. Why wouldn't this work? One reason I can think of is that Iso transfers aren't reliable. But then regular RS232-type serial transfers aren't reliable either. The only other reason is that the USB stack itself has an unpredictable amount of overhead. However I think it should fall within an acceptable range for RT applications. 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/