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I've run into problems with latency when sending and receiving messages
to and from my USB device. The device is controlled via firmware
commands which are sent over the bulk out pipe and whose responses are
read in through the bulk in pipe.
Each firmware command takes 0.5 seconds with my driver, which is 3
orders of magnitude too slow. The corresponding Windows driver for the
same device reports firmware command turnaround times of between 500 and
I've also noticed data transfer is too slow by a factor of 20 or so. My
guess is that maybe something's working in low speed or full speed mode,
instead of high speed. However, that wouldn't explain the terrible
latency I'm experiencing. The amounts of data that I'm transmitting are
so low (~20 bytes, on average), that data transfer time can't be the reason.
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