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    ALSA: firewire-lib: compute the value of second field in cycle count for IT context · 73fc7f08
    Takashi Sakamoto authored
    
    
    In callback function of isochronous context, u32 variable is passed for
    cycle count. The value of this variable comes from DMA descriptors of 1394
    Open Host Controller Interface (1394 OHCI). In the specification, DMA
    descriptors transport lower 3 bits for second field and full cycle field in
    16 bits field, therefore 16 bits of the u32 variable are available. The
    value for second is modulo 8, and the value for cycle is modulo 8,000.
    
    Currently, ALSA firewire-lib module don't use the value of the second
    field, because the value is useless to calculate presentation timestamp in
    IEC 61883-6. However, the value may be useful for debugging. In later
    commit, it will be printed with the other parameters for debugging.
    
    This commit makes this module to handle the whole cycle count including
    second. The value is calculated by cycle unit. The existed code is already
    written with ignoring the value of second, thus this commit causes no
    issues.
    
    Signed-off-by: default avatarTakashi Sakamoto <o-takashi@sakamocchi.jp>
    Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
    73fc7f08