Hi,

I'm trying to figure out how to do a control read where I expect the
result to be more than 1 packet. I'm guessing that I'm supposed to
submit more than one urb, with subsequent urbs having a NULL
setup_packet?

When I submit a single urb, I set the transfer_buffer_length to zero
(because otherwise the host tries to send OUT packets during the data
stage). So how does the USB subsystem know how much IN data it can fit
in that urb? Does it assume that it has at least one packet size in that
urb?

And how does the USB subsystem decide that an overflow has occurred? If
it runs out of urbs but it hasn't detected a short packet to mark the
end of the data stage? And what becomes of extra urbs submitted that
aren't needed to satisfy the data stage? Do they get returned at the end
of the data stage?

Thanks,
--gmcnutt


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