• Takashi Sakamoto's avatar
    ALSA: fireface: add stream management functionality · 75d6d898
    Takashi Sakamoto authored
    
    
    This commit adds management functionality for packet streaming.
    
    As long as investigating Fireface 400, there're three modes depending
    on sampling transmission frequency. The number of data channels in each
    data block is different depending on the mode. The set of available
    data channels for each mode might be different for each protocol and
    model.
    
    The length of registers for the number of isochronous channel is just
    three bits, therefore 0-7ch are available.
    
    When bus reset occurs on IEEE 1394 bus, the device discontinues to
    transmit packets. This commit aborts PCM substreams at bus reset handler.
    
    As I described in followed commits, The device manages its sampling clock
    independently of sampling transmission frequency against IEC 61883-6.
    Thus, it's a lower cost to change the sampling transmission frequency,
    while data fetch between streaming layer and DSP require larger buffer
    for resampling. As a result, device latency might tend to be larger than
    ASICs for IEC 61883-1/6 such as DM1000/DM1100/DM1500 (BeBoB),
    DiceII/TCD2210/TCD2220/TCD3070 and OXFW970/971.
    Signed-off-by: default avatarTakashi Sakamoto <o-takashi@sakamocchi.jp>
    Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
    75d6d898
ff.h 3.53 KB