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    SubjectRe: [PATCH] usb: add new usb gadget for ACM and mass storage
    On Fri, Sep 16, 2011 at 10:18 AM, Sebastian Andrzej Siewior
    <> wrote:
    > Would it be possible to come up with a gadget-hub driver which can have
    > multiple gadget attached? This should get rid of this kind of gadget
    > drivers, right?
    > Sebastian
    > --


    To literally make a gadget that can emulate a hub (where it could
    present port 1 as function x, port 2 as function y etc) would require
    special hardware. The (bus speed) translations and (ack/nak) timings
    are speced very tightly for hubs (see chapter 11 of the spec). Each
    function would have its own usb bus address - otherwise one gadget
    could not nak while another transfered data. Each bus address would
    have to meet the spec in responding to all signaling.

    Think about how the individual functions would announce themselves to
    the host - when the port is enabled the available/speed pull ups would
    have to be set, but other ports have to be in their old state.
    Reset/Suspend signaling would have to be handled only by the selected

    So while it would make multiple function gadgets somewhat easier I
    don't see how it is possible, do composite and/or compound gadgets

    Regards, Steve

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