On Mon, May 5, 2014 at 8:38 PM, Dan Williams <dcbw@xxxxxxxxxx> wrote: > On Mon, 2014-05-05 at 11:07 +0530, Suresh Kumar N. wrote: >> Hi, >> >> I am new to udev and device enumeration. >> >> I am interested to know how USB Data Card would get enumerated. >> >> Based on my understanding Data Card can get enumerated below 2 possible ways - >> 1. As a modem >> 2. As a Network Interface Card (NIC) > > Or both at the same time. > >> Is there a Standard defining the way a Data Card should be enumerated? > > There is no single standard. There is a few "standards" and multiple > proprietary mechanisms, and sometimes these are combined in the same > device. > > The device simply enumerates as a normal USB device, providing to the > host computer one or more USB interfaces. > > Each USB interface can be any one of: > > 1) serial interface (AT, QCDM, WMC, WDM, CDC-ACM, etc) > 2) pseudo-ethernet NIC (proprietary, CDC-ETHER, CDC-NCM, etc) In such case (pseudo-ethernet NIC) do we assume that the firmware on the USB Dongle is responsible to establish IP address? In other words how does IP address allocation occur in this case? > 3) proprietary control protocols (CnS, QMI, etc) > 4) standard non-serial control protocols (MBIM) > > A modem can provide any of these in combination. Which port speaks what > protocol is detected by one or more of the following methods: > > a) USB VID/PID and interface number hardcoded in the drivers or in > userland udev rules > b) USB interface type (eg, serial port or NIC port, done in userland) > c) probing with known request/response to determine different > communication protocols used if the port type is indeterminate Thanks for the information. > > Dan > >> Please correct if my understanding is not correct or incomplete. >> >> Thanks in advance for your clarifications. >> >> Warm Regards, >> Suresh >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-usb" in >> the body of a message to majordomo@xxxxxxxxxxxxxxx >> More majordomo info at http://vger.kernel.org/majordomo-info.html > > -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
