- int snd_ctl_add_slave(struct snd_kcontrol * master, struct snd_kcontrol * slave);
- vmaster element
- slave element to add
Add a virtual slave control to the given master element created via snd_ctl_create_virtual_master beforehand.
All slaves must be the same type (returning the same information via info callback). The function doesn't check it, so it's your responsibility.
Also, some additional limitations: at most two channels, logarithmic volume control (dB level) thus no linear volume, master can only attenuate the volume without gain
Zero if successful or a negative error code.