MOTU units transfer/receive messages in each data block of their
isochronous packet payload. A part of content in the message is cleard for
MIDI message transmission, while the rest is unknown yet. Additional
features are required to assist users and developers to reveal the
details.
This commit adds tracepoints for the purpose. The tracepoints are designed
for MOTU's protocol version 2 and 3 (Protocol version 1 is not upstreamed
yet). In the tracepoints, events are probed to gather first two 24 bit
data chunks of each data block. The chunks are formatted into elements
of 64 bit array with padding in MSB.
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Unique protocol is used for MOTU FireWire series. In this protocol,
data block format is not compliant to AM824 in IEC 61883-1/6. Each of
the data block consists of 24 bit data chunks, except for a first
quadlet. The quadlet is used for source packet header (SPH) described
in IEC 61883-1.
The sequence of SPH seems to represent presentation timestamp
corresponding to included data. Developers have experienced that invalid
sequence brings disorder of units in the series.
Unfortunately, current implementation of ALSA IEC 61883-1/6 engine and
firewire-motu driver brings periodical noises to the units at sampling
transmission frequency based on 44.1 kHz. The engine generates the SPH with
even interval and this mechanism seems not to be suitable to the units.
Further work is required for this issue and infrastructure is preferable
to assist the work.
This commit adds tracepoints for the purpose. In the tracepoints, events
are probed to gather the SPHs from each data blocks.
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Takashi Sakamoto