My last message was misleading. It's not that acp-audio-config-flag is 0, but rather that reading it was successful. Let me try this again, and using hex values that are probably more familiar:
[ 5.692748] snd_pci_acp6x 0000:c3:00.5: pci->revision=0x70
[ 5.692828] snd_pci_acp6x 0000:c3:00.5: read acp-audio-config-flag: success
[ 5.692855] snd_pci_acp6x 0000:c3:00.5: acp-audio-config-flag value: 0x10