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--- Comment #30 from John Dallaway <[email protected]> 2010-10-21 09:57:39 BST --- (In reply to comment #29) > (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. Chris, thanks for your reply. I had assumed that this is how (eg) USB docking stations work. Perhaps they use a vendor-specific class. Is there any way to avoid the blocking usbs_*_start() call when using dynamic endpoint configuration? I was wondering if the endpoint structs should be retrieved within usbs_*_wait_until_configured(), which is already a blocking call, rather than within usbs_*_start(). usbs_*_wait_until_configured() would not be called from usbs_*_start(). This would make a call to usbs_*_wait_until_configured() essential rather than advisable but would avoid a hardware-dependent variation in blocking/non-blocking behaviour of usbs_*_start(). Does this make sense to you? Will the driver re-use the same endpoint structures if the cable is disconnected and then reconnected? I'm just wanting to check we have all bases covered here. -- Configure bugmail: http://bugs.ecos.sourceware.org/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are on the CC list for the bug.
