Commit cb828f1b3e introduced an unconditional flush() call in the
open() routine's body, and passed its return value in verbatim form to
open() callers. Some of the transports/cables for serial communication
yield the SR_ERR_NA return value. Consider this a non-fatal condition.
Unbreak the CP2110 HID chip's flush() implementation. Don't expect a
return value of 0 from HID write calls, instead expect to see the number
of written bytes for successful calls.
This was tested with ch9325 (UT-D04), cp2110 (UT-D09) and bu86x.
Gerhard Sittig
Uwe Hermann