diff --git a/sound/firewire/amdtp.c b/sound/firewire/amdtp.c
index 51aad680886d..39033876593e 100644
--- a/sound/firewire/amdtp.c
+++ b/sound/firewire/amdtp.c
@@ -653,6 +653,8 @@ static void handle_in_packet(struct amdtp_stream *s,
 				cip_header[0]);
 			goto err;
 		}
+		if (s->flags & CIP_WRONG_DBS)
+			data_block_quadlets = s->data_block_quadlets;
 
 		data_blocks = (payload_quadlets - 2) / data_block_quadlets;
 	}
diff --git a/sound/firewire/amdtp.h b/sound/firewire/amdtp.h
index 1ca1a193bbc0..f334ae51e44f 100644
--- a/sound/firewire/amdtp.h
+++ b/sound/firewire/amdtp.h
@@ -21,6 +21,8 @@
  * @CIP_EMPTY_WITH_TAG0: Only for in-stream. Empty in-packets have TAG0.
  * @CIP_DBC_IS_END_EVENT: Only for in-stream. The value of dbc in an in-packet
  *	corresponds to the end of event in the packet. Out of IEC 61883.
+ * @CIP_WRONG_DBS: Only for in-stream. The value of dbs is wrong in in-packets.
+ *	The value of data_block_quadlets is used instead of reported value.
  */
 enum cip_flags {
 	CIP_NONBLOCKING		= 0x00,
@@ -28,6 +30,7 @@ enum cip_flags {
 	CIP_SYNC_TO_DEVICE	= 0x02,
 	CIP_EMPTY_WITH_TAG0	= 0x04,
 	CIP_DBC_IS_END_EVENT	= 0x08,
+	CIP_WRONG_DBS		= 0x10,
 };
 
 /**
diff --git a/sound/firewire/fireworks/fireworks.c b/sound/firewire/fireworks/fireworks.c
index 307fb2f250da..02b3259059f0 100644
--- a/sound/firewire/fireworks/fireworks.c
+++ b/sound/firewire/fireworks/fireworks.c
@@ -205,6 +205,8 @@ efw_probe(struct fw_unit *unit,
 	err = get_hardware_info(efw);
 	if (err < 0)
 		goto error;
+	if (entry->model_id == MODEL_ECHO_AUDIOFIRE_9)
+		efw->is_af9 = true;
 
 	err = snd_efw_stream_init_duplex(efw);
 	if (err < 0)
diff --git a/sound/firewire/fireworks/fireworks.h b/sound/firewire/fireworks/fireworks.h
index ce511be4611b..9534e93e3a36 100644
--- a/sound/firewire/fireworks/fireworks.h
+++ b/sound/firewire/fireworks/fireworks.h
@@ -61,6 +61,9 @@ struct snd_efw {
 	u32 seqnum;
 	bool resp_addr_changable;
 
+	/* for quirks */
+	bool is_af9;
+
 	unsigned int midi_in_ports;
 	unsigned int midi_out_ports;
 
diff --git a/sound/firewire/fireworks/fireworks_stream.c b/sound/firewire/fireworks/fireworks_stream.c
index d687b047446b..7447af72ae30 100644
--- a/sound/firewire/fireworks/fireworks_stream.c
+++ b/sound/firewire/fireworks/fireworks_stream.c
@@ -198,6 +198,9 @@ int snd_efw_stream_init_duplex(struct snd_efw *efw)
 	efw->tx_stream.flags |= CIP_EMPTY_WITH_TAG0;
 	/* Fireworks has its own meaning for dbc. */
 	efw->tx_stream.flags |= CIP_DBC_IS_END_EVENT;
+	/* AudioFire9 always reports wrong dbs. */
+	if (efw->is_af9)
+		efw->tx_stream.flags |= CIP_WRONG_DBS;
 
 	err = init_stream(efw, &efw->rx_stream);
 	if (err < 0) {