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[bluetooth-dev] Ericsson Bluetooth Module - USB Initialization problem with Linux


I recently asked for help with a problem establishing communication with the USB
port on the Ericsson Bluetooth module (ROK 107 008) in the Linux environment.
The problem appears to be that on power-up the module alternately looks at its
UART and USB ports until it hears from one or the other, but that while looking
at one, it is blind to activity on the other. Linux only tries assigning an
address to a newly detected USB device twice before quitting. Increasing
HUB_PROBE_TRIES from 2 to 20 in hub.c results in 100% success, and typically
requires 6 - 8 tries before address assignment succeeds.

Thanks to Mark Corner for pointing me in the right direction!

By the way, the Ericsson module does not have the required 1.5k pull-up on the
USB D+ line, but does have a weak (100k) pull-up on D- which causes the hub to
see either nothing or, worse yet, a low speed (1.5 M) device if you don't supply
an external pullup on D+.


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