On Sun, 20 Aug 2017 14:25:02 +0200, Takashi Sakamoto wrote:
Hi,
This patchset is to add support for MOTU AudioExpress. Any PCM frames and MIDI messages are transferred in rx/tx isochronous packets. Correspondingly, this adds an arrangement for specification flag for position of existence flag of MIDI messages.
I note that this unit has a quirk of acknowledge code against request subaction on asynchronous communication. In detail, please refer to 2nd patch of this set. To easy my development, I applied a patch to 'firewire-ohci' module on my develop ment tree. You can see the content in the end of this message. It's really a band-aid for the aim and can not be merged as what it is.
Unfortunately, current implementations of IEC 61883-1/6 packet streaming engine is not good enough in a point to presentation timestamp, as I reported[1]. Any plaback stream for the unit still causes periodical noise.
[1] [alsa-devel] Status of ALSA firewire stack at Linux v4.12 development period http://mailman.alsa-project.org/pipermail/alsa-devel/2017-April/120061.html
-------- 8< -------- diff --git a/drivers/firewire/ohci.c b/drivers/firewire/ohci.c index 8bf89267dc25..06a0906a9b56 100644 --- a/drivers/firewire/ohci.c +++ b/drivers/firewire/ohci.c @@ -1499,6 +1499,10 @@ static int handle_at_packet(struct context *context, packet->ack = evt - 0x10; break;
case 0x10:packet->ack = ACK_PENDING;break;case OHCI1394_evt_no_status: if (context->flushing) { packet->ack = RCODE_GENERATION;-------- 8< --------
Takashi Sakamoto (2): ALSA: firewire-motu: add specification flag for position of flag for MIDI messages ALSA: firewire-motu: add support for MOTU Audio Express
Applied both patches. Thanks.
Takashi