Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262285AbTEMUKm (ORCPT ); Tue, 13 May 2003 16:10:42 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262310AbTEMUKm (ORCPT ); Tue, 13 May 2003 16:10:42 -0400 Received: from tmr-02.dsl.thebiz.net ([216.238.38.204]:50953 "EHLO gatekeeper.tmr.com") by vger.kernel.org with ESMTP id S262285AbTEMUKk (ORCPT ); Tue, 13 May 2003 16:10:40 -0400 Date: Tue, 13 May 2003 16:17:48 -0400 (EDT) From: Bill Davidsen To: Paul Fulghum cc: "linux-kernel@vger.kernel.org" Subject: Re: 2.5.69 Interrupt Latency In-Reply-To: <1052840106.2255.24.camel@diemos> 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: 1901 Lines: 46 On 13 May 2003, Paul Fulghum wrote: > On Tue, 2003-05-13 at 10:26, Alan Stern wrote: > > > Putting in a sanity check for the global suspend state will be very easy. > > But I would like to point out that this "global suspend" does not refer to > > the entire system, only the USB bus. > > That is a problem then, because the delay can still > occur during normal system operation. > > > I'm not sure under what > > circumstances the bus is placed in global suspend; I think it's just when > > there are no devices attached (or the last remaining device is detached). > > > > However, there have been cases on my own system where turning off the only > > USB peripheral caused the driver to bounce between suspend_hc() and > > wakeup_hc() several times without any apparent explanation -- possibly as > > a result of transient electrical signals on the bus (?). So perhaps > > moving that delay out of the ISR isn't such a bad idea. > > Agreed. If this can happen on functional USB controllers > when no devices are attached, then it is a serious problem. Instead of trying to guess when to do it, could the sleep be replaced by setting a flag bit to indicate that a sleep was needed before using the hardware? Then the sleep could be done when needed but no noise on the USB bus wouldn't hurt. 1 - there may be many places, I thought of that but didn't look since someone will tell me if it's a problem. 2 - if you don't use USB why not just take the driver out? It would be nice to prevent the problem, of course. -- bill davidsen CTO, TMR Associates, Inc Doing interesting things with little computers since 1979. - 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/