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 it's called at each time when the value is changed.
Zero.