How to log USB modem data for a specific device?

[Jeffrey Walton]

On Mon, Nov 11, 2019 at 11:31 AM Greg KH <greg at kroah.com> wrote:
>
> On Mon, Nov 11, 2019 at 11:11:06AM -0500, Jeffrey Walton wrote:
> > Hi Everyone,
> >
> > I'm having trouble with a C application that opens a USB modem. The
> > application is not receiving some data from a USR modem. Conexant
> > modems are OK.
> >
> > I'm working through
> > https://www.kernel.org/doc/Documentation/usb/usbmon.txt . I found the
> > modem at Bus=01 Dev=24:
> >
> > T:  Bus=01 Lev=03 Prnt=07 Port=00 Cnt=01 Dev#= 24 Spd=480  MxCh= 0
> > D:  Ver= 2.00 Cls=02(comm.) Sub=00 Prot=00 MxPS=64 #Cfgs=  1
> > P:  Vendor=0baf ProdID=0303 Rev= 2.00
> > S:  Manufacturer=U.S.Robotics
> > S:  Product=USB Modem
> >
> > This is where my confusion lies. It is not clear to me how to
> > determine which socket to use for step #3 in usbmon.txt. Step #3 says:
> >
> >    # cat /sys/kernel/debug/usb/usbmon/3u > /tmp/1.mon.out
> >
> > How do I determine which socket to use for Bus=01 Dev=24?
>
> From the above documentation, it says to use "3u" for all devices on the
> 3rd bus.  You want the 1st bus, right?  So did you try using "1u"?
>
> I think wireshark can intrepret usbmon output, so maybe just use that
> instead and point it at the USB bus you want to watch?

Thanks Greg.

I want Bus 1, but I want Device 24 (not all devices).

Jef