Tascam IF-FW/DM support is 'experimental' at this time.
After modifying the udev rules to make the Tascam recognised as a ffado device (see ffado devices page comment), I did not manage to get the driver to work consistently. Some starts of jackd work and others don't. Also the working sessions do experience some XRuns, maybe once every minute or so.
I have attached two logfiles, created with the SVN trunk checkout of 10/7/2011 (compiled with DEBUG=True), using:
jackd --verbose -d firewire -v6 -r 48000 > logfile 2>&1
So all output (standard and errors) are in the log files. One file is of a working session and one of a failed session for comparison.
I have never looked at the bebob/ffado code before and have no logfiles of working cards to compare, but it appears the driver complains about rather large timing differences between expected and actual.
I am happy to try other settings and generate other log files, or help in any other way I can, but I must admit my coding skills have become somewhat rusty.
Many thanks for any help you can give! It would be great if we can get the Tascam to work properly, as they regularly appear on ebay and are great value!