From: Eyal Lebedinsky <eyal@eyal.emu.id.au>
To: list linux-usb <linux-usb@vger.kernel.org>
Subject: Re: usb port enumeration changed? [resolved]
Date: Tue, 27 Jul 2021 16:43:35 +1000 [thread overview]
Message-ID: <a9c21e7b-0175-26b4-2ef7-84cd3c6ef1ec@eyal.emu.id.au> (raw)
In-Reply-To: <20210727022345.GA138425@rowland.harvard.edu>
See end of message.
On 27/07/2021 12.23, Alan Stern wrote:
> 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?
Seeing the confidence of the reply I decided to do more testing.
- booting the old kernel did not fix it.
- unplugging and re-plugging the devices did not help.
I then crawled under the table and followed the large cables bundle to find that I should have
trusted my instruments (the USB system).
While the correct cable was plugged into the correct socket, the far end used an extension which
*was* plugged into the wrong thing. I then remembered that at one time the cable was pulled off
accidentally and quickly re-attached...
In short, I am stupid and apology for the noise.
> Alan Stern
Regards,
--
Eyal Lebedinsky (eyal@eyal.emu.id.au)
next prev parent reply other threads:[~2021-07-27 6:43 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-27 1:15 usb port enumeration changed? Eyal Lebedinsky
2021-07-27 2:23 ` Alan Stern
2021-07-27 6:43 ` Eyal Lebedinsky [this message]
2021-07-27 13:39 ` usb port enumeration changed? [resolved] Alan Stern
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=a9c21e7b-0175-26b4-2ef7-84cd3c6ef1ec@eyal.emu.id.au \
--to=eyal@eyal.emu.id.au \
--cc=linux-usb@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).