Man page 9 : snd_ctl_add_vmaster_hook

snd_ctl_add_vmaster_hook - Add a hook to a vmaster control

int snd_ctl_add_vmaster_hook(struct snd_kcontrol *  kcontrol , void (* hook ) (void *private_data, int), void *  private_data );

kcontrol
    vmaster kctl element

hook
    the hook function

private_data
    the private_data pointer to be saved

Adds the given hook to the vmaster control element so that itAqs called at each time when the value is changed.

Zero.