Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755702AbYGSUgF (ORCPT ); Sat, 19 Jul 2008 16:36:05 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753532AbYGSUfx (ORCPT ); Sat, 19 Jul 2008 16:35:53 -0400 Received: from netrider.rowland.org ([192.131.102.5]:1880 "HELO netrider.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1753087AbYGSUfx (ORCPT ); Sat, 19 Jul 2008 16:35:53 -0400 Date: Sat, 19 Jul 2008 16:35:52 -0400 (EDT) From: Alan Stern X-X-Sender: stern@netrider.rowland.org To: Simon Arlott cc: Arjan van de Ven , Kernel development list , USB list Subject: Re: Re [patch 2/3] fastboot: turn the USB hostcontroller initcalls into async initcalls In-Reply-To: <48820904.2090707@simon.arlott.org.uk> 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: 1449 Lines: 36 On Sat, 19 Jul 2008, Simon Arlott wrote: > usb/core/hub.c: > > /* USB 2.0 spec, 7.1.7.3 / fig 7-29: > * > * Between connect detection and reset signaling there must be a delay > * of 100ms at least for debounce and power-settling. The corresponding > * timer shall restart whenever the downstream port detects a disconnect. > * > * Apparently there are some bluetooth and irda-dongles and a number of > * low-speed devices for which this debounce period may last over a second. > * Not covered by the spec - but easy to deal with. > * > * This implementation uses a 1500ms total debounce timeout; if the > * connection isn't stable by then it returns -ETIMEDOUT. It checks > * every 25ms for transient disconnects. When the port status has been > * unchanged for 100ms it returns the port status. > */ > > Could it do that for all ports on the hub in parallel instead? In fact it will, to a large extent. The new code isn't present in 2.6.26 but it ought to be in 2.6.27-rc1. However Arjan wasn't talking about debounce delays; he was talking about port-power-on delays. A nice improvement would be to combine the two types of delay into one. I'll look into it... 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/