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    SubjectRe: [PATCHv3 2/4] usb: gadget: replace "is_dualspeed" with "max_speed"
    On Tue, 23 Aug 2011, Michal Nazarewicz wrote:

    > My understanding was that one could consciously create a composite gadget
    > such that not all of the functions support all of the speeds.

    That's an important point. If somebody wants to build a composite
    gadget that includes both midi and storage support, the storage driver
    would be able to go all the way up to SuperSpeed (or rather, it will
    once Felipe's patch is finished and merged) but the midi driver would
    only support full speed. So what speed should the UDC connect at?

    In cases like this there's really no way to know. Ultimately the best
    approach would be to update the midi driver, but that's a long-term
    sort of thing.

    Usually when the kernel can't decide something, it asks the user for
    help (by allowing the user to specify the speed via a module parameter,
    for instance). In this case even that wouldn't work, because the
    gadget's userspace isn't aware of which functions the host's user will
    want to utilize.

    At the moment I don't know the best answer. This is something we
    should all think about.

    Alan Stern

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      Last update: 2011-08-23 16:39    [W:0.033 / U:8.404 seconds]
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