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
