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    SubjectRe: [PATCH] usb: udc: add gadget state kobject uevent
    On Tue, Jul 16, 2013 at 11:49:07AM +0800, Rong Wang wrote:
    > Hi Greg,
    >
    > The USB on our platform can change roles between HOST and GADGET, but
    > it is not capable of OTG.

    That kind of sounds like the definition of OTG :)

    > When the USB changes between roles the udev will run some scripts
    > automatically according to the udev rules.

    What exactly does udev/userspace see when the roles change?

    And what can trigger the change in roles?

    > The default role is GADGET, and we bind the g_mass_storage to the USB
    > GADGET role.
    >
    > We should secure the back end file storage between the device and the
    > host PC connecting to our device.
    > We need to know when the GADGET is really connect to a host PC, then
    > we can umount the file on the device
    > and export it to the g_mass_storage.

    I thought you already get an event for this, otherwise no one would be
    able to properly deal with this.

    > The question is since we default GADGET, so the g_mass_storage.ko is
    > installed early but connecting to a host PC
    > is randomly, But the udev has no idea when a host PC connects our device.
    >
    > So we consider it's reasonable to let the udev know the GADGET device state.
    > Is there any alternative to our question?

    I thought we already export events for gadget device states, have you
    looked for them? I can't dig through the code at the moment, but this
    seems like a pretty common issue...

    Felipe, any ideas?

    greg k-h


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