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    SubjectRE: [PATCH v12 7/8] usb: Adding SuperSpeed support to dummy_hcd
    On Wed, 25 May 2011, Tanya Brokhman wrote:

    > Ok so just to make sure I understand you correctly:
    > You want me to remove the modification made to usb_composite_probe() and
    > instead add:
    > static struct usb_gadget_driver composite_driver = {
    > + .speed = USB_SPEE_SUPER,
    > +#else
    > .speed = USB_SPEED_HIGH,
    > +#endif
    > .unbind = composite_unbind,
    > And then you'll be ok with change? Or is there anything else?
    > If this is it then I'm relieved :) and of course will update the code.

    I have looked this over more carefully. It turns out that both of you
    have misunderstood the purpose of CONFIG_USB_GADGET_DUALSPEED (and by
    extension, CONFIG_USB_GADGET_SUPERSPEED). In fact, the existing
    Kconfig file is also wrong.

    The _only_ reason for CONFIG_USB_GADGET_DUALSPEED is so that gadget
    drivers can use conditional compilation to avoid including the
    high-speed descriptors when the UDC doesn't support high-speed
    operation. That's all. This means that the
    CONFIG_USB_GAGDET_DUALSPEED option does not need to be
    user-controllable in Kconfig. It should default to N, and UDC drivers
    that support high speed should select it.

    The same should be true of CONFIG_USB_GADGET_HIGHSPEED. It should not
    be user-controllable. It should default to N, and UDC drivers that
    support SuperSpeed operation (after these patches, only dummy-hcd)
    should select it.

    There remains the other question, about whether composite_driver.speed
    should be set to USB_SPEED_SUPER. I think the matter can be settled at
    runtime. Iterate through all the function drivers; if all of them
    support SuperSpeed and CONFIG_USB_GADGET_SUPERSPEED is enabled then set
    composite_driver.speed to USB_SPEED_SUPER. Otherwise, if all of them
    support high speed and CONFIG_USB_GADGET_DUALSPEED is enabled then set
    composite_driver.speed to USB_SPEED_HIGH. Otherwise set it to

    Alan Stern

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