• Takashi Sakamoto's avatar
    ALSA: fireworks: perform sequence replay for media clock recovery · a105f642
    Takashi Sakamoto authored
    Echo Digital Audio Corporation had US patent US7599388B2 titled as
    'System and method for high-bandwidth serial bus data transfer'. In the
    patent, dual-banked shared memory is used to deliver data between
    serial bus transmission and processor in FIFO way. The patent seems to be
    used for Fireworks board module. The mechanism is not compliant to
    synchronization based on presentation time expressed in syt field
    of CIP header. Fireworks board module takes care of the sequence of
    the number of data blocks per packet and just ignores the value of syt
    field.
    
    This commit takes fireworks driver to performs sequence replay for media
    clock recovery. As long as I tested, Audiofire 2 and 4 have a quirk to
    skip an isochronous cycle several thousands after starting packet
    transmission.
    
    The sequence replay is tested with below models:
     * Loud Technology Mackie 400f
     * Echo Audio Audiofire 12 (DSP model)
     * Echo Audio Audiofire 12 (FPGA model)
     * Echo Audio Audiofire 8 (DSP model)
     * Echo Audio Audiofire 8 (FPGA model)
     * Echo Audio Audiofire Pre8
     * Echo Audio Audiofire 4
     * Echo Audio Audiofire 2
    Signed-off-by: default avatarTakashi Sakamoto <o-takashi@sakamocchi.jp>
    Link: https://lore.kernel.org/r/20210531025103.17880-3-o-takashi@sakamocchi.jpSigned-off-by: default avatarTakashi Iwai <tiwai@suse.de>
    a105f642
fireworks_stream.c 8.71 KB