ALSA: firewire-motu: fix detection for S/PDIF source on optical interface in v2 protocol

The devices in protocol version 2 has a register with flag for IEC 60958
signal detection as source of sampling clock without discrimination
between coaxial and optical interfaces. On the other hand, current
implementation of driver manage to interpret type of signal on optical
interface instead.

This commit fixes the detection of optical/coaxial interface for S/PDIF
signal.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Link: https://lore.kernel.org/r/20210623075941.72562-2-o-takashi@sakamocchi.jp
Signed-off-by: Takashi Iwai <tiwai@suse.de>

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;
-		break;
-	}
-	case 2:
 			*src = SND_MOTU_CLOCK_SOURCE_SPDIF_ON_COAX;
 		break;
+	}
 	case 3:
 		*src = SND_MOTU_CLOCK_SOURCE_SPH;
 		break;