Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761654AbXFIVVM (ORCPT ); Sat, 9 Jun 2007 17:21:12 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757297AbXFIVU7 (ORCPT ); Sat, 9 Jun 2007 17:20:59 -0400 Received: from netrider.rowland.org ([192.131.102.5]:4161 "HELO netrider.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1754739AbXFIVU6 (ORCPT ); Sat, 9 Jun 2007 17:20:58 -0400 Date: Sat, 9 Jun 2007 17:20:56 -0400 (EDT) From: Alan Stern X-X-Sender: stern@netrider.rowland.org To: Robert de Rooy cc: Jiri Kosina , Greg KH , , USB development list , Kernel development list Subject: Re: [linux-usb-devel] ThinkPad T41 - Strange USB 2.0 behaviour In-Reply-To: <4669D608.2070505@gmail.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1633 Lines: 36 On Sat, 9 Jun 2007, Robert de Rooy wrote: > Alan Stern wrote: > > Robert, it would help somewhat if you could build a kernel with > > CONFIG_USB_DEBUG turned on and post the dmesg log showing what happens > > when you plug in one of those non-working devices. > > > Sorry, yes I should have done that before... Unfortunately you posted the system log file instead of the dmesg log, and your syslogd was configured not to retain debug-level messages. > > Yes, in principle Linux can be made to switch over to full speed when > > high speed fails. But there are limitations: The switchover would work > > only for devices plugged directly into the computer, not for devices > > plugged into a high-speed hub. And some Linux systems (not regular > > PCs) have EHCI implementations that don't allow such a switch -- or > > if they do, I'm not aware of how to accomplish it. > > > Interesting, I have a USB 2.0 hub, but have not tried it, mainly because > I need to find a power supply for it first. > But regardless if the hub works as USB 2.0 or 1.1, it could be that > another hub behaves differently, just like I have one USB 2.0 memory key > that still works as such. You did not understand my point. Regardless of how the hub behaves, there is no way to tell it that a device plugged into a particular port should not be allowed to run at high speed. 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/