Re: usbtest and pattern=1

[Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>]

On Tue, 15 Jan 2008, David Brownell wrote:

> On Tuesday 15 January 2008, Matthieu CASTET wrote:

> > So if on the host we send data on the bulk endpoint after the 
> > set_altsetting but the device isn't fast enough, the usb_ep_enable & 
> > usb_ep_queue won't be done and we can lose packet due to the flush.
> > 
> > How the sync between host and device is supposed to work ?
> 
> The peripheral doesn't return from SET_INTERFACE (set_altsetting)
> until after the endpoints are enabled.

At a lower level, the peripheral doesn't ACK the Status stage of the
Set-Interface request until all the operations (re-enabling endpoints,
flushing fifos, etc.) are finished.  The gadget driver insures this by
not returning from its setup routine until everything is ready.

Alan Stern


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