snd_ctl_add_slave (9)

int snd_ctl_add_slave(struct snd_kcontrol * master, struct snd_kcontrol * slave);

master

vmaster element

slave

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.