Hi,
after some research and help from the ffado list i think that the JACK 2's
firewire backend implementation does not honor the -d command line flag to
set a specific interface.
The effect is that when multiple devices are present, no matter what -d is
set to, all devices are aggregated. In most cases this fine and wanted.
However there is no warning or error message for bogus -dhw arguments and
it's not possible to start one specific interface only without
workarounds.
With the following diff (just 3 lines from JACK 1 codebase) it works as
expected, even using guid:xxx (which is a very nice feature).
Please review and consider merge.
Thanks,
Thomas