From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B5EC7C49EA3 for ; Mon, 28 Jun 2021 14:26:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9FFB861C9C for ; Mon, 28 Jun 2021 14:26:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233589AbhF1O2u (ORCPT ); Mon, 28 Jun 2021 10:28:50 -0400 Received: from netrider.rowland.org ([192.131.102.5]:53175 "HELO netrider.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S232542AbhF1O0p (ORCPT ); Mon, 28 Jun 2021 10:26:45 -0400 Received: (qmail 657845 invoked by uid 1000); 28 Jun 2021 10:24:18 -0400 Date: Mon, 28 Jun 2021 10:24:18 -0400 From: Alan Stern To: Matt Corallo Cc: linux-usb@vger.kernel.org, linux-amlogic@lists.infradead.org, Martin Blumenstingl Subject: Re: ODROID-C1/-C2 USB Detection only triggered by some devices Message-ID: <20210628142418.GC656159@rowland.harvard.edu> References: <0badab7c-f12e-e9ed-2f90-2cf5f25f4038@bluematt.me> <20210628005825.GA638648@rowland.harvard.edu> <20210628011628.GC638648@rowland.harvard.edu> <0c62655d-738c-4d71-6b7b-fe7fa90b54e3@bluematt.me> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0c62655d-738c-4d71-6b7b-fe7fa90b54e3@bluematt.me> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On Sun, Jun 27, 2021 at 09:24:45PM -0400, Matt Corallo wrote: > > > On 6/27/21 21:16, Alan Stern wrote: > > You mean that only devices in the first group are affected by this bug? > > Devices in the second group are always detected correctly regardless of > > what else is plugged in? (This contradicts what you wrote above.) > > > Correct. Ignoring hotplug (ie on fresh boot or lsusb -vvv), the devices in > the second group work great. The devices in the first group do too, but only > if a device from the second group is present. Okay. You can try collecting some usbmon traces to see what's going on. First test: Boot with nothing plugged in, start a usbmon trace for bus 0 (cat /sys/kernel/debug/usb/usbmon/0u >mon1.txt), plug in a first-group device, run lsusb -v to trigger enumeration, and then kill the "cat" process. Second test: Same as the first except that you boot with a second-group device already plugged in. The differences between the two traces may indicate where the problem is. Alan Stern