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author | Takashi Sakamoto <o-takashi@sakamocchi.jp> | 2021-05-27 21:26:09 +0900 |
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committer | Takashi Iwai <tiwai@suse.de> | 2021-05-28 10:44:01 +0200 |
commit | f9e5ecdfc2c2f2a87f4aa8aa3d0216016103d769 (patch) | |
tree | d6b086a1bb37a5cf51e2f2deaba6f5c70b1a866d /sound/firewire/motu/motu-stream.c | |
parent | d955782da2901f977ef1ededba8a2764e35c1187 (diff) |
ALSA: firewire-lib: add replay target to cache sequence of packet
In design of audio and music unit in IEEE 1394 bus, feedback of
effective sampling transfer frequency (STF) is delivered by packets
transferred from device. The devices supported by ALSA firewire stack
are categorized to three groups regarding to it.
* Group 1:
* Echo Audio Fireworks board module
* Oxford Semiconductor OXFW971 ASIC
* Digidesign Digi00x family
* Tascam FireWire series
* RME Fireface series
* Group 2:
* BridgeCo. DM1000/DM1100/DM1500 ASICs for BeBoB solution
* TC Applied Technologies DICE ASICs
* Group 3:
* Mark of the Unicord FireWire series
In group 1, the effective STF is determined by the sequence of the number
of events per packet. In group 2, the sequence of presentation timestamp
expressed in syt field of CIP header is interpreted as well. In group 3,
the presentation timestamp is expressed in source packet header (SPH) of
each data block.
I note that some models doesn't take care of effective STF with large
internal buffer. It's reasonable to name it as group 0:
* Group 0
* Oxford Semiconductor OXFW970 ASIC
The effective STF is known to be slightly different from nominal STF for
all of devices, and to be different between the devices. Furthermore, the
effective STF is known to be shifted for long-period transmission. This
makes it hard for software to satisfy the effective STF when processing
packets to the device.
The effective STF is deterministic as a result of analyzing the batch of
packet transferred from the device. For the analysis, caching the sequence
of parameter in the packet is required.
This commit adds an option so that AMDTP domain structure takes AMDTP
stream structure to cache the sequence of parameters in packet transferred
from the device. The parameters are offset ticks of syt field against the
cycle to receive the packet and the number of data blocks per packet.
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Link: https://lore.kernel.org/r/20210527122611.173711-2-o-takashi@sakamocchi.jp
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound/firewire/motu/motu-stream.c')
-rw-r--r-- | sound/firewire/motu/motu-stream.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/sound/firewire/motu/motu-stream.c b/sound/firewire/motu/motu-stream.c index 925241ae2551..5af9d7487cdc 100644 --- a/sound/firewire/motu/motu-stream.c +++ b/sound/firewire/motu/motu-stream.c @@ -260,7 +260,7 @@ int snd_motu_stream_start_duplex(struct snd_motu *motu) if (err < 0) goto stop_streams; - err = amdtp_domain_start(&motu->domain, 0); + err = amdtp_domain_start(&motu->domain, 0, false); if (err < 0) goto stop_streams; |