Re: Understanding 'lsusb -t'

[Greg KH <greg@kroah.com>]

On Fri, Aug 30, 2024 at 11:43:39PM +1000, Eyal Lebedinsky wrote:
> On 30/8/24 11:41 pm, Eyal Lebedinsky wrote:
> > On 30/8/24 10:32 pm, Greg KH wrote:
> > > On Fri, Aug 30, 2024 at 10:14:20PM +1000, Eyal Lebedinsky wrote:
> > > > I assume that the generated list is a tree, so each leaf (Device/If) is on only one point.
> > > > 
> > > > I note this output:
> > > > 
> > > > $ lsusb -tv
> > > > /:  Bus 001.Port 001: Dev 001, Class=root_hub, Driver=xhci_hcd/16p, 480M
> > > >      ID 1d6b:0002 Linux Foundation 2.0 root hub
> > > > [trimmed]
> > > >      |__ Port 004: Dev 004, If 0, Class=Hub, Driver=hub/4p, 480M
> > > > [trimmed]
> > > >      |__ Port 005: Dev 006, If 0, Class=Hub, Driver=hub/4p, 480M
> > > > [trimmed]
> > > >      |__ Port 006: Dev 019, If 0, Class=Hub, Driver=hub/4p, 480M
> > > >          ID 2109:2817 VIA Labs, Inc.
> > > > /:  Bus 002.Port 001: Dev 001, Class=root_hub, Driver=xhci_hcd/10p, 10000M
> > > > [trimmed]
> > > >      |__ Port 006: Dev 006, If 0, Class=Hub, Driver=hub/4p, 5000M
> > > >          ID 2109:0817 VIA Labs, Inc.
> > > > 
> > > > I removed some content that is not relevant to my question.
> > > > 
> > > > Note the Bus 001.Port 006 and Bus 002.Port 006 entries.
> > > > 
> > > > I verified that both are for the same (one) device. They do not show when I disconnect it.
> > > > The device is an external 4-port USB3.0 hub. It is listed once as 480M and once as 5000M.
> > > > Nothing is plugged into any of the four ports.
> > > > 
> > > > Is this correct? Why does this device show twice in the list?
> > > 
> > > That's odd, as the same device shouldn't be on multiple busses.  Busses
> > > are a "root port" on the system (i.e. a new PCI controller device), so
> > > are you sure you just don't have multiple devices with the same
> > > device/vendor id?
> > 
> > The hub is on an extension cable, and I just unplug it the hub.
> > 
> > > What is the diff between running the command before and after removing a
> > > single device?
> > 
> > $ lsusb -tv >lsusb-all.log
> > $ lsusb -tv >lsusb-less.log
> > $ diff -u lsusb-all.log lsusb-less.log
> > --- lsusb-all.log       2024-08-30 23:39:09.782062079 +1000
> > +++ lsusb-less.log      2024-08-30 23:39:22.608987407 +1000
> > @@ -48,8 +48,6 @@
> >               ID 0c45:7401 Microdia TEMPer Temperature Sensor
> >           |__ Port 004: Dev 018, If 1, Class=Human Interface Device, Driver=[none], 1.5M
> >               ID 0c45:7401 Microdia TEMPer Temperature Sensor
> > -    |__ Port 006: Dev 019, If 0, Class=Hub, Driver=hub/4p, 480M
> > -        ID 2109:2817 VIA Labs, Inc.
> >   /:  Bus 002.Port 001: Dev 001, Class=root_hub, Driver=xhci_hcd/10p, 10000M
> >       ID 1d6b:0003 Linux Foundation 3.0 root hub
> >       |__ Port 004: Dev 002, If 0, Class=Hub, Driver=hub/4p, 5000M
> > @@ -58,5 +56,3 @@
> >               ID 0bda:0411 Realtek Semiconductor Corp. Hub
> >       |__ Port 005: Dev 003, If 0, Class=Hub, Driver=hub/4p, 5000M
> >           ID 05e3:0612 Genesys Logic, Inc. Hub
> > -    |__ Port 006: Dev 006, If 0, Class=Hub, Driver=hub/4p, 5000M
> > -        ID 2109:0817 VIA Labs, Inc.
> 
> Also, here these the log messages when I reconnect the hub:
> 
> 2024-08-30T23:41:52+10:00 e7.eyal.emu.id.au kernel: usb 1-6: New USB device strings: Mfr=1, Product=2, SerialNumber=0
> 2024-08-30T23:41:52+10:00 e7.eyal.emu.id.au kernel: usb 1-6: Product: USB2.0 Hub
> 2024-08-30T23:41:52+10:00 e7.eyal.emu.id.au kernel: usb 1-6: Manufacturer: VIA Labs, Inc.
> 2024-08-30T23:41:52+10:00 e7.eyal.emu.id.au kernel: hub 1-6:1.0: USB hub found
> 2024-08-30T23:41:52+10:00 e7.eyal.emu.id.au kernel: hub 1-6:1.0: 4 ports detected
> 2024-08-30T23:41:52+10:00 e7.eyal.emu.id.au kernel: usb 2-6: new SuperSpeed USB device number 7 using xhci_hcd
> 2024-08-30T23:41:52+10:00 e7.eyal.emu.id.au kernel: usb 2-6: New USB device found, idVendor=2109, idProduct=0817, bcdDevice= 0.50
> 2024-08-30T23:41:52+10:00 e7.eyal.emu.id.au kernel: usb 2-6: New USB device strings: Mfr=1, Product=2, SerialNumber=0
> 2024-08-30T23:41:52+10:00 e7.eyal.emu.id.au kernel: usb 2-6: Product: USB3.0 Hub
> 2024-08-30T23:41:52+10:00 e7.eyal.emu.id.au kernel: usb 2-6: Manufacturer: VIA Labs, Inc.
> 2024-08-30T23:41:52+10:00 e7.eyal.emu.id.au kernel: hub 2-6:1.0: USB hub found
> 2024-08-30T23:41:52+10:00 e7.eyal.emu.id.au kernel: hub 2-6:1.0: 4 ports detected

Extension cables are very wierd, and you are right, this is two
different hubs on two ports.  Is this a thunderbolt device somehow?

Anyway, as long as everything is working properly, all should be good.

What happens when you plug a device into this cable at the other end,
does it show up twice?  Or just once?

thanks,

greg k-h