https://git.kernel.org/cgit/linux/kernel/git/tiwai/sound.git/commit/sound/pci/ca0106?id=49c88b85b53767f97eb8c9171cb0b976c62a0114
it is the virtual master playback volume control
https:/ /git.kernel. org/cgit/ linux/kernel/ git/tiwai/ sound.git/ commit/ sound/pci/ ca0106? id=49c88b85b537 67f97eb8c9171cb 0b976c62a0114
it is the virtual master playback volume control