3 files changed, 18 insertions, 2 deletions

diff --git a/sound/firewire/amdtp.c b/sound/firewire/amdtp.c
index dce4c6dd3f6d..51aad680886d 100644
--- a/sound/firewire/amdtp.c
+++ b/sound/firewire/amdtp.c
@@ -620,6 +620,7 @@ static void handle_in_packet(struct amdtp_stream *s,
         u32 cip_header[2];
         unsigned int data_blocks, data_block_quadlets, data_block_counter;
         struct snd_pcm_substream *pcm = NULL;
+        bool lost;
 
         cip_header[0] = be32_to_cpu(buffer[0]);
         cip_header[1] = be32_to_cpu(buffer[1]);
@@ -658,7 +659,13 @@ static void handle_in_packet(struct amdtp_stream *s,
 
         /* Check data block counter continuity */
         data_block_counter = cip_header[0] & AMDTP_DBC_MASK;
-        if (data_block_counter != s->data_block_counter) {
+        if (!(s->flags & CIP_DBC_IS_END_EVENT))
+                lost = data_block_counter != s->data_block_counter;
+        else
+                lost = data_block_counter !=
+                       ((s->data_block_counter + data_blocks) & 0xff);
+
+        if (lost) {
                 dev_info(&s->unit->device,
                          "Detect discontinuity of CIP: %02X %02X\n",
                          s->data_block_counter, data_block_counter);
@@ -676,7 +683,11 @@ static void handle_in_packet(struct amdtp_stream *s,
                         amdtp_pull_midi(s, buffer, data_blocks);
         }
 
-        s->data_block_counter = (data_block_counter + data_blocks) & 0xff;
+        if (s->flags & CIP_DBC_IS_END_EVENT)
+                s->data_block_counter = data_block_counter;
+        else
+                s->data_block_counter =
+                                (data_block_counter + data_blocks) & 0xff;
 end:
         if (queue_in_packet(s) < 0)
                 goto err;
diff --git a/sound/firewire/amdtp.h b/sound/firewire/amdtp.h
index 96b96ec812b2..1ca1a193bbc0 100644
--- a/sound/firewire/amdtp.h
+++ b/sound/firewire/amdtp.h
@@ -19,12 +19,15 @@
  * @CIP_SYNC_TO_DEVICE: In sync to device mode, time stamp in out packets is
  *      generated by in packets. Defaultly this driver generates timestamp.
  * @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.
  */
 enum cip_flags {
         CIP_NONBLOCKING         = 0x00,
         CIP_BLOCKING            = 0x01,
         CIP_SYNC_TO_DEVICE      = 0x02,
         CIP_EMPTY_WITH_TAG0     = 0x04,
+        CIP_DBC_IS_END_EVENT    = 0x08,
 };
 
 /**
diff --git a/sound/firewire/fireworks/fireworks_stream.c b/sound/firewire/fireworks/fireworks_stream.c
index 360e871bf838..d687b047446b 100644
--- a/sound/firewire/fireworks/fireworks_stream.c
+++ b/sound/firewire/fireworks/fireworks_stream.c
@@ -196,6 +196,8 @@ int snd_efw_stream_init_duplex(struct snd_efw *efw)
                 goto end;
         /* Fireworks transmits NODATA packets with TAG0. */
         efw->tx_stream.flags |= CIP_EMPTY_WITH_TAG0;
+        /* Fireworks has its own meaning for dbc. */
+        efw->tx_stream.flags |= CIP_DBC_IS_END_EVENT;
 
         err = init_stream(efw, &efw->rx_stream);
         if (err < 0) {