Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755909AbYCaRP4 (ORCPT ); Mon, 31 Mar 2008 13:15:56 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751548AbYCaRPq (ORCPT ); Mon, 31 Mar 2008 13:15:46 -0400 Received: from rtr.ca ([76.10.145.34]:2417 "EHLO mail.rtr.ca" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751258AbYCaRPq (ORCPT ); Mon, 31 Mar 2008 13:15:46 -0400 Message-ID: <47F11C3D.9080704@rtr.ca> Date: Mon, 31 Mar 2008 13:15:41 -0400 From: Mark Lord Organization: Real-Time Remedies Inc. User-Agent: Thunderbird 2.0.0.12 (X11/20080213) MIME-Version: 1.0 To: Oliver Neukum Cc: Pavel Machek , Linux Kernel , Greg KH , Andrew Morton , jikos@suse.cz Subject: Re: 2.6.25-rc7: Ugh. References: <47EBBD57.30902@rtr.ca> <200803311704.37256.oliver@neukum.org> <47F0FD8E.4090005@rtr.ca> <200803311837.30129.oliver@neukum.org> <47F1196E.9090509@rtr.ca> In-Reply-To: <47F1196E.9090509@rtr.ca> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1933 Lines: 46 Mark Lord wrote: > Oliver Neukum wrote: >> Am Montag, 31. März 2008 17:04:46 schrieb Mark Lord: >>> Oliver Neukum wrote: >>>> Am Montag, 31. März 2008 16:39:33 schrieb Mark Lord: .. >>>>> Still want USB_SUSPEND=n ? Please explain. >>>> It looks like you are hanging in the kthread for autosuspending. >>>> Compiling that out should confirm it. >>> .. >>> >>> Okay, and once we see that it works fine: then what? >> >> We'll combine that information with the result of only removing usbhid >> and arrive at a pretty good idea where in the kernel the hang occurs. >> There are only two functions that touch autosuspend in the usbhid code. >> So if it works with usbhid unloaded, either of them should be to blame. > .. > It does still hang with *usbhid* unloaded, > but not if all USB stuff is unloaded. .. And it does *not* hang with # CONFIG_USB_SUSPEND is not set. > I have figured out a way to make this much more reproducible now: > When suspended, the notebook does not supply +5V over USB. > But with a voltmeter, I discovered that there is sufficient capacitance > on the USB +5V, that it takes many minutes for the voltage to decay > from 5.1V down to near 0V. > > Resuming while the voltage is still relatively high, generally works. > Resuming after the voltage drops to near zero, always fails (with USB > modules loaded). > > So I've put a 2Kohm resistor across the USB +5V lines, > forcing it to decay to zero within about 5 seconds. > This helps a lot for debugging here. > > It probably also provides a vital clue as to what is wrong. > Resume seems to generally work when the USB devices maintain > some amount of standby power, and always fails when they don't. -- 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/