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=-5.2 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 95506C432BE for ; Tue, 27 Jul 2021 02:23:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 79CD760FEB for ; Tue, 27 Jul 2021 02:23:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234226AbhG0BnS (ORCPT ); Mon, 26 Jul 2021 21:43:18 -0400 Received: from netrider.rowland.org ([192.131.102.5]:46637 "HELO netrider.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S234251AbhG0BnS (ORCPT ); Mon, 26 Jul 2021 21:43:18 -0400 Received: (qmail 138855 invoked by uid 1000); 26 Jul 2021 22:23:45 -0400 Date: Mon, 26 Jul 2021 22:23:45 -0400 From: Alan Stern To: Eyal Lebedinsky Cc: list linux-usb Subject: Re: usb port enumeration changed? Message-ID: <20210727022345.GA138425@rowland.harvard.edu> References: <261c3985-28bc-b203-59fa-ecb650f2b42d@eyal.emu.id.au> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <261c3985-28bc-b203-59fa-ecb650f2b42d@eyal.emu.id.au> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On Tue, Jul 27, 2021 at 11:15:11AM +1000, Eyal Lebedinsky wrote: > I know that device numbers change, but bus/port numbers are stable and reflect the physical layout > of the hubs and devices. I relied for years on these port numbers to identify specific (otherwise > identical) devices. Port numbers are stable. Bus numbers aren't. (They do tend to be stable but there are no guarantees.) > Searching the list (I am now subscribed) and the web did not yield an answer. > > For example, I have two TEMPer temperature sensor devices attached. They are both plugged into > a 4-port USB3 hub. They are on ports 3 and 4. Port 2 is unused and port 1 has a bluetooth radio > attached. I also have 5 dvb usb tuners which stayed in their old positions. > > Until now (fedora 34, last on 5.12.17-300.fc34.x86_64), I would see this: > > $ lsusb > Bus 001 Device 013: ID 0c45:7401 Microdia TEMPer Temperature Sensor > Bus 001 Device 025: ID 0c45:7401 Microdia TEMPer Temperature Sensor > > $ lsusb -t > /: Bus 02.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/10p, 10000M > |__ Port 4: Dev 2, If 0, Class=Hub, Driver=hub/4p, 5000M > |__ Port 4: Dev 4, If 0, Class=Hub, Driver=hub/4p, 5000M > |__ Port 5: Dev 3, If 0, Class=Hub, Driver=hub/4p, 5000M > /: Bus 01.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/16p, 480M > |__ Port 2: Dev 26, If 0, Class=Hub, Driver=hub/4p, 480M > |__ Port 2: Dev 27, If 1, Class=Human Interface Device, Driver=usbhid, 12M > |__ Port 2: Dev 27, If 0, Class=Human Interface Device, Driver=usbhid, 12M > |__ Port 4: Dev 3, If 0, Class=Hub, Driver=hub/4p, 480M > |__ Port 3: Dev 10, If 1, Class=Vendor Specific Class, Driver=, 480M > |__ Port 3: Dev 10, If 0, Class=Vendor Specific Class, Driver=dvb_usb_rtl28xxu, 480M > |__ Port 1: Dev 6, If 0, Class=Vendor Specific Class, Driver=dvb_usb_rtl28xxu, 480M > |__ Port 1: Dev 6, If 1, Class=Vendor Specific Class, Driver=, 480M > |__ Port 4: Dev 12, If 0, Class=Hub, Driver=hub/4p, 480M > |__ Port 3: Dev 15, If 0, Class=Printer, Driver=usblp, 12M > |__ Port 1: Dev 14, If 1, Class=Vendor Specific Class, Driver=, 480M > |__ Port 1: Dev 14, If 0, Class=Vendor Specific Class, Driver=dvb_usb_rtl28xxu, 480M > |__ Port 4: Dev 16, If 0, Class=Vendor Specific Class, Driver=dvb_usb_rtl28xxu, 480M > |__ Port 4: Dev 16, If 1, Class=Vendor Specific Class, Driver=, 480M > |__ Port 2: Dev 8, If 0, Class=Vendor Specific Class, Driver=dvb_usb_rtl28xxu, 480M > |__ Port 2: Dev 8, If 1, Class=Vendor Specific Class, Driver=, 480M > |__ Port 5: Dev 5, If 0, Class=Hub, Driver=hub/4p, 480M > |__ Port 1: Dev 20, If 0, Class=Wireless, Driver=btusb, 12M > |__ Port 1: Dev 20, If 1, Class=Wireless, Driver=btusb, 12M > |__ Port 3: Dev 25, If 0, Class=Human Interface Device, Driver=, 1.5M <<<<< > |__ Port 3: Dev 25, If 1, Class=Human Interface Device, Driver=, 1.5M <<<<< > |__ Port 4: Dev 13, If 0, Class=Human Interface Device, Driver=, 1.5M <<<<< > |__ Port 4: Dev 13, If 1, Class=Human Interface Device, Driver=, 1.5M <<<<< > |__ Port 6: Dev 19, If 0, Class=Human Interface Device, Driver=usbfs, 1.5M > > The TEMPer devices show on Bus 01 as was always: > Port 5.Port 3 (Dev 11) In fact it is device 25; see above. There is o device 11 in the lsusb output. > Port 5.Port 4 (Dev 13) > > After rebooting the newly installed kernel 5.13.4-200.fc34.x86_64 I get: > > $ lsusb > Bus 001 Device 012: ID 0c45:7401 Microdia TEMPer Temperature Sensor > Bus 001 Device 003: ID 0c45:7401 Microdia TEMPer Temperature Sensor > > $ lsusb -t > /: Bus 02.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/10p, 10000M > |__ Port 4: Dev 2, If 0, Class=Hub, Driver=hub/4p, 5000M > |__ Port 4: Dev 4, If 0, Class=Hub, Driver=hub/4p, 5000M > |__ Port 5: Dev 3, If 0, Class=Hub, Driver=hub/4p, 5000M > /: Bus 01.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/16p, 480M > |__ Port 2: Dev 2, If 0, Class=Hub, Driver=hub/4p, 480M > |__ Port 2: Dev 4, If 1, Class=Human Interface Device, Driver=usbhid, 12M > |__ Port 2: Dev 4, If 0, Class=Human Interface Device, Driver=usbhid, 12M > |__ Port 3: Dev 3, If 0, Class=Human Interface Device, Driver=, 1.5M <<<<< > |__ Port 3: Dev 3, If 1, Class=Human Interface Device, Driver=, 1.5M <<<<< > |__ Port 4: Dev 5, If 0, Class=Hub, Driver=hub/4p, 480M > |__ Port 3: Dev 11, If 1, Class=Vendor Specific Class, Driver=, 480M > |__ Port 3: Dev 11, If 0, Class=Vendor Specific Class, Driver=dvb_usb_rtl28xxu, 480M > |__ Port 1: Dev 7, If 0, Class=Vendor Specific Class, Driver=dvb_usb_rtl28xxu, 480M > |__ Port 1: Dev 7, If 1, Class=Vendor Specific Class, Driver=, 480M > |__ Port 4: Dev 13, If 0, Class=Hub, Driver=hub/4p, 480M > |__ Port 3: Dev 15, If 0, Class=Printer, Driver=usblp, 12M > |__ Port 1: Dev 14, If 1, Class=Vendor Specific Class, Driver=, 480M > |__ Port 1: Dev 14, If 0, Class=Vendor Specific Class, Driver=dvb_usb_rtl28xxu, 480M > |__ Port 4: Dev 16, If 0, Class=Vendor Specific Class, Driver=dvb_usb_rtl28xxu, 480M > |__ Port 4: Dev 16, If 1, Class=Vendor Specific Class, Driver=, 480M > |__ Port 2: Dev 9, If 0, Class=Vendor Specific Class, Driver=dvb_usb_rtl28xxu, 480M > |__ Port 2: Dev 9, If 1, Class=Vendor Specific Class, Driver=, 480M > |__ Port 5: Dev 6, If 0, Class=Hub, Driver=hub/4p, 480M > |__ Port 1: Dev 10, If 0, Class=Wireless, Driver=btusb, 12M > |__ Port 1: Dev 10, If 1, Class=Wireless, Driver=btusb, 12M > |__ Port 3: Dev 12, If 0, Class=Human Interface Device, Driver=, 1.5M <<<<< > |__ Port 3: Dev 12, If 1, Class=Human Interface Device, Driver=, 1.5M <<<<< > |__ Port 6: Dev 18, If 0, Class=Human Interface Device, Driver=usbfs, 1.5M > > One can see that the TEMPer devices are now showing on Bus 01 but in separate positions: > Port 3 (Dev 3) new position > Port 5.Port 3 (Dev 12) old position Are you certain that device 3 really is one of the TEMPer devices and not something else? > This, naturally, confuses my script that collects the data from these sensors (I use temper-poll). Are you certain you didn't change the wiring? I can't think of any other explanation. > Is this an intentional change? Nope. > If so then what is the way to stably disambiguate usb devices (there is no s/n available)? Using port paths is a fairly good way to go. Unless the devices get unplugged and then plugged back into different ports. > If no change was expected then does this reflect a possible hwr problem here? No, it represents a physical impossibility. Consider the following thought experiment: You unplug the four-port hub that is device 6 on bus 1 (port 5). That will of course also disconnect anything that is plugged into that hub, presumably including your two temperature sensors. But if one of them is plugged into port 3 of the root hub instead, it won't be affected by this operation. So what really happens? Alan Stern