ALSA: firewire-motu: add stream management functionality
This commit adds a functionality to manage packet streaming for MOTU FireWire series. The streaming is not controlled by CMP, thus against IEC 61883-1. Write transaction to certain addresses start/stop packet streaming. Transactions to 0x'ffff'f000'0b00 results in isochronous channel number for both directions and starting/stopping transmission of packets. The isochronous channel number is represented in 6 bit field, thus units can identify the channels up to 64, as IEEE 1394 bus specification described. Transactions to 0x'ffff'f000'0b10 results in packet format for both directions and transmission speed. When each of data block includes fixed part of data chunks only, corresponding flags stand. When bus reset occurs, the units continue to transmit packets with non-contiguous data block counter. This causes discontinuity detection in packet streaming engine and ALSA PCM applications receives EPIPE from any I/O operation. In this case, typical applications manage to recover corresponding PCM substream. This behaviour is kicked much earlier than callback of bus reset handler by Linux FireWire subsystem, therefore status of packet streaming is not changed in the handler. Signed-off-by:Takashi Sakamoto <o-takashi@sakamocchi.jp> Signed-off-by:
Takashi Iwai <tiwai@suse.de>
parent
2e76701b
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