1 files changed, 14 insertions, 0 deletions

diff --git a/sound/firewire/amdtp-stream.c b/sound/firewire/amdtp-stream.c
index 46f1167bf69f..4d86da0355ba 100644
--- a/sound/firewire/amdtp-stream.c
+++ b/sound/firewire/amdtp-stream.c
@@ -566,6 +566,13 @@ static inline u32 increment_cycle_count(u32 cycle, unsigned int addend)
         return cycle;
 }
 
+static inline u32 decrement_cycle_count(u32 cycle, unsigned int subtrahend)
+{
+        if (cycle < subtrahend)
+                cycle += 8 * CYCLES_PER_SECOND;
+        return cycle - subtrahend;
+}
+
 static void out_stream_callback(struct fw_iso_context *context, u32 tstamp,
                                 size_t header_length, void *header,
                                 void *private_data)
@@ -607,6 +614,7 @@ static void in_stream_callback(struct fw_iso_context *context, u32 tstamp,
         unsigned int payload_quadlets, max_payload_quadlets;
         unsigned int data_blocks;
         __be32 *buffer, *headers = header;
+        u32 cycle;
 
         if (s->packet_index < 0)
                 return;
@@ -614,10 +622,16 @@ static void in_stream_callback(struct fw_iso_context *context, u32 tstamp,
         /* The number of packets in buffer */
         packets = header_length / IN_PACKET_HEADER_SIZE;
 
+        cycle = compute_cycle_count(tstamp);
+
+        /* Align to actual cycle count for the last packet. */
+        cycle = decrement_cycle_count(cycle, packets);
+
         /* For buffer-over-run prevention. */
         max_payload_quadlets = amdtp_stream_get_max_payload(s) / 4;
 
         for (p = 0; p < packets; p++) {
+                cycle = increment_cycle_count(cycle, 1);
                 buffer = s->buffer.packets[s->packet_index].buffer;
 
                 /* The number of quadlets in this packet */