• Takashi Sakamoto's avatar
    ALSA: firewire-digi00x: add support for asynchronous messaging · 44b73088
    Takashi Sakamoto authored
    Digi 002/003 family uses asynchronous transaction for messaging.
    The address to transmit this message is stored on a certain register.
    
    This commit allocates a range of address on OHCI 1394 host controller
    to handle the messaging. As long as I know, the purpose of this message
    seems to notify lost of synchronization. While, the meaning of content
    of the message is not clear.
    
    Actual examples of this messaging:
     * When clock source is set as internal:
     - 0x00007051
     - 0x00007052
     - 0x00007054
     - 0x00007057
     - 0x00007058
     * When clock source is set as somewhat external:
     - 0x00009000
     - 0x00009010
     - 0x00009020
     - 0x00009021
     - 0x00009022
    
    The lost often occurs when using internal clock source. In this case,
    users hear sounds with quite short gap every several minutes. In fact,
    the lost is recovered temporarily.
    
    When using with external clock source, the lost seems not to occur. The
    mechanism is not clear yet.
    Signed-off-by: default avatarTakashi Sakamoto <o-takashi@sakamocchi.jp>
    Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
    44b73088
digi00x-hwdep.c 4.4 KB