I am opening this ticket after a discussion on ffado-devel, just to leave a trace in this trac, since the problem is still open.
The problem is with Focusrite Saffire Pro24, Ubuntu Precise Pangolin 12.04 (using jackdmp). I am using recent revisions of svn (last time I observed the problem was with r2161).
The command "ffado-test BusReset" sometimes never ends, being blocked after printing the line:
Doing busreset on port 0
When I launch qjackctl, this bug prevents the application from responding. If I kill the process ffado-test, then qjackctl continues working, and jack is started normally.
I join a corresponding extract of /var/log/kern.log and the result of strace ffado-test BusReset