How to log USB modem data for a specific device?

[Greg KH]

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?

good luck!

greg k-h