Messages in this thread | | | Date | Mon, 15 Jul 2013 23:31:17 -0700 | From | Greg KH <> | Subject | Re: [PATCH] usb: udc: add gadget state kobject uevent |
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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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