linux 3.0.8 alsa数据流程分析

ALSA打开数据流程
    soc_pcm_open => cpu_dai->driver->ops->startup => platform->driver->ops->open => codec_dai->driver->ops->startup \
    => rtd->dai_link->ops->startup  
 
    ALSA的HW_param流程
    soc_pcm_hw_params => rtd->dai_link->ops->hw_params => codec_dai->driver->ops->hw_params => cpu_dai->driver->ops->hw_params \
    => platform->driver->ops->hw_params
 
    ALSA的Prepare流程
    snd_pcm_prepare => snd_pcm_action_nonatomic => snd_pcm_action_group => snd_pcm_do_prepare => substream->ops->prepare \
    => soc_pcm_prepare => rtd->dai_link->ops->prepare => platform->driver->ops->prepare => codec_dai->driver->ops->prepare \
           => cpu_dai->driver->ops->prepare  
 
    ALSA的Write流程
    snd_pcm_playback_ioctl => snd_pcm_playback_ioctl1 => SNDRV_PCM_IOCTL_WRITEN_FRAMES => snd_pcm_lib_writev => snd_pcm_lib_write1 \
    => |||| =>  snd_pcm_lib_writev_transfer => copy_from_user [copy user speace data to dma]  
    snd_pcm_start => snd_pcm_action => snd_pcm_action_group => snd_pcm_do_start =>  substream->ops->trigger
 
    ALSA的Trigger流程
    substream->ops->trigger => soc_pcm_trigger => codec_dai->driver->ops->trigger => platform->driver->ops->trigger \
    => cpu_dai->driver->ops->trigger
    
    ALSA的cset流程
    snd_ctl_ioctl => SNDRV_CTL_IOCTL_ELEM_WRITE => snd_ctl_elem_write_user => snd_ctl_elem_write => kctl->put => codec->write