[PATCH] ALSA: oxfw: fix functioal regression for silence in Apogee Duet FireWire

[Takashi Sakamoto]

OXFW 971 has no function to use the value in syt field of received
isochronous packet for playback timing generation. In kernel prepatch for
v5.14, ALSA OXFW driver got change to send NO_INFO value in the field
instead of actual timing value. The change brings Apogee Duet FireWire to
generate no playback sound, while output meter moves.

As long as I investigate, _any_ value in the syt field takes the device to
generate sound. It's reasonable to think that the device just ignores data
blocks in packet with NO_INFO value in its syt field for audio data
processing.

This commit adds a new flag for the quirk to fix regression.

Fixes: 029ffc429440 ("ALSA: oxfw: perform sequence replay for media clock recovery")
Cc: <stable at vger.kernel.org>
Signed-off-by: Takashi Sakamoto <o-takashi at sakamocchi.jp>
---
 sound/firewire/oxfw/oxfw-stream.c | 9 ++++++++-
 sound/firewire/oxfw/oxfw.c        | 6 ++++--
 sound/firewire/oxfw/oxfw.h        | 5 +++++
 3 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/sound/firewire/oxfw/oxfw-stream.c b/sound/firewire/oxfw/oxfw-stream.c
index 0ef242fdd3bc..fff18b5d4e05 100644
--- a/sound/firewire/oxfw/oxfw-stream.c
+++ b/sound/firewire/oxfw/oxfw-stream.c
@@ -153,7 +153,7 @@ static int init_stream(struct snd_oxfw *oxfw, struct amdtp_stream *stream)
 	struct cmp_connection *conn;
 	enum cmp_direction c_dir;
 	enum amdtp_stream_direction s_dir;
-	unsigned int flags = CIP_UNAWARE_SYT;
+	unsigned int flags = 0;
 	int err;
 
 	if (!(oxfw->quirks & SND_OXFW_QUIRK_BLOCKING_TRANSMISSION))
@@ -161,6 +161,13 @@ static int init_stream(struct snd_oxfw *oxfw, struct amdtp_stream *stream)
 	else
 		flags |= CIP_BLOCKING;
 
+	// OXFW 970/971 has no function to generate playback timing according to the sequence
+	// of value in syt field, thus the packet should include NO_INFO value in the field.
+	// However, some models just ignore data blocks in packet with NO_INFO for audio data
+	// processing.
+	if (!(oxfw->quirks & SND_OXFW_QUIRK_IGNORE_NO_INFO_PACKET))
+		flags |= CIP_UNAWARE_SYT;
+
 	if (stream == &oxfw->tx_stream) {
 		conn = &oxfw->out_conn;
 		c_dir = CMP_OUTPUT;
diff --git a/sound/firewire/oxfw/oxfw.c b/sound/firewire/oxfw/oxfw.c
index 84971d78d152..cb5b5e3a481b 100644
--- a/sound/firewire/oxfw/oxfw.c
+++ b/sound/firewire/oxfw/oxfw.c
@@ -159,8 +159,10 @@ static int detect_quirks(struct snd_oxfw *oxfw, const struct ieee1394_device_id
 		return snd_oxfw_scs1x_add(oxfw);
 	}
 
-	if (entry->vendor_id == OUI_APOGEE && entry->model_id == MODEL_DUET_FW)
-		oxfw->quirks |= SND_OXFW_QUIRK_BLOCKING_TRANSMISSION;
+	if (entry->vendor_id == OUI_APOGEE && entry->model_id == MODEL_DUET_FW) {
+		oxfw->quirks |= SND_OXFW_QUIRK_BLOCKING_TRANSMISSION |
+				SND_OXFW_QUIRK_IGNORE_NO_INFO_PACKET;
+	}
 
 	/*
 	 * TASCAM FireOne has physical control and requires a pair of additional
diff --git a/sound/firewire/oxfw/oxfw.h b/sound/firewire/oxfw/oxfw.h
index ee47abcb0c90..c13034f6c2ca 100644
--- a/sound/firewire/oxfw/oxfw.h
+++ b/sound/firewire/oxfw/oxfw.h
@@ -42,6 +42,11 @@ enum snd_oxfw_quirk {
 	SND_OXFW_QUIRK_BLOCKING_TRANSMISSION = 0x04,
 	// Stanton SCS1.d and SCS1.m support unique transaction.
 	SND_OXFW_QUIRK_SCS_TRANSACTION = 0x08,
+	// Apogee Duet FireWire ignores data blocks in packet with NO_INFO for audio data
+	// processing, while output level meter moves. Any value in syt field of packet takes
+	// the device to process audio data even if the value is invalid in a point of
+	// IEC 61883-1/6.
+	SND_OXFW_QUIRK_IGNORE_NO_INFO_PACKET = 0x10,
 };
 
 /* This is an arbitrary number for convinience. */
-- 
2.30.2