From Stefan Richter.
The DICE protocol involves "owner lock" register at the audio interface.
The snd-dice kernel driver takes this lock as soon as the DICE device is
being probed by the kernel (i.e. even before any application actually
opens the ALSA device for streaming). Thus, the FFADO streaming driver
fails to start when snd-dice is present on the system.
So far this was only made known by a cryptic -v3 debug message. Reform it
into a message which is always logged even without -v# command line
parameter, and which proposes solutions to the problem in highlevel terms.
Note, the condition which is triggering the message can have other causes,
like a previous jackd+ffado session having crashed without locking out, or
even another initiator PC being present on the bus. However, now that more
and more distributions ship snd-dice, presence of the kernel driver is the
far likelier reason.