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[Bug 1001024] STM32 USB driver and proposed USB API change


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--- Comment #29 from Chris Holgate <chris@zynaptic.com> 2010-10-20 19:27:14 BST ---
(In reply to comment #28)

> I'm concerned that usbs_serial_start() will now block until a connection has
> been established and endpoints have been configured. How will this affect the
> implementation multiple function devices over a single USB port where multiple
> usbs_*_start() functions may need to be called? I'm thinking that it should be
> possible to present both a mass storage device and a serial device (for
> example) over a single physical interface. 

I don't think this scenario is supported by the USB spec - a single end device
can only ever implement a single class driver, as identified by the device
descriptor.  To get multiple class drivers running behind a single USB
connector, you would need to emulate a USB hub and hang the class drivers off
the back of that - one per virtual USB slave device.

While such a feature would be nice to have, it would need quite a bit of extra
work and may require additional features which are not present on the currently
supported hardware.

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