diff --git a/sound/firewire/motu/motu-protocol-v2.c b/sound/firewire/motu/motu-protocol-v2.c
index 784073aa1026..f0a0ecad4d74 100644
--- a/sound/firewire/motu/motu-protocol-v2.c
+++ b/sound/firewire/motu/motu-protocol-v2.c
@@ -86,24 +86,23 @@ static int detect_clock_source_optical_model(struct snd_motu *motu, u32 data,
 		*src = SND_MOTU_CLOCK_SOURCE_INTERNAL;
 		break;
 	case 1:
+		*src = SND_MOTU_CLOCK_SOURCE_ADAT_ON_OPT;
+		break;
+	case 2:
 	{
 		__be32 reg;
 
 		// To check the configuration of optical interface.
-		int err = snd_motu_transaction_read(motu, V2_IN_OUT_CONF_OFFSET,
-						    &reg, sizeof(reg));
+		int err = snd_motu_transaction_read(motu, V2_IN_OUT_CONF_OFFSET, &reg, sizeof(reg));
 		if (err < 0)
 			return err;
 
-		if (be32_to_cpu(reg) & 0x00000200)
+		if (((data & V2_OPT_IN_IFACE_MASK) >> V2_OPT_IN_IFACE_SHIFT) == V2_OPT_IFACE_MODE_SPDIF)
 			*src = SND_MOTU_CLOCK_SOURCE_SPDIF_ON_OPT;
 		else
-			*src = SND_MOTU_CLOCK_SOURCE_ADAT_ON_OPT;
+			*src = SND_MOTU_CLOCK_SOURCE_SPDIF_ON_COAX;
 		break;
 	}
-	case 2:
-		*src = SND_MOTU_CLOCK_SOURCE_SPDIF_ON_COAX;
-		break;
 	case 3:
 		*src = SND_MOTU_CLOCK_SOURCE_SPH;
 		break;