1 files changed, 57 insertions, 17 deletions

diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index cdac5179d..9245f52d4 100644
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -1383,6 +1383,56 @@ static inline void fill_playback_urb_dsd_dop(struct snd_usb_substream *subs,
 			subs->hwptr_done++;
 		}
 	}
+	if (subs->hwptr_done >= runtime->buffer_size * stride)
+		subs->hwptr_done -= runtime->buffer_size * stride;
+}
+
+static void copy_to_urb(struct snd_usb_substream *subs, struct urb *urb,
+			int offset, int stride, unsigned int bytes)
+{
+	struct snd_pcm_runtime *runtime = subs->pcm_substream->runtime;
+
+	if (subs->hwptr_done + bytes > runtime->buffer_size * stride) {
+		/* err, the transferred area goes over buffer boundary. */
+		unsigned int bytes1 =
+			runtime->buffer_size * stride - subs->hwptr_done;
+		memcpy(urb->transfer_buffer + offset,
+		       runtime->dma_area + subs->hwptr_done, bytes1);
+		memcpy(urb->transfer_buffer + offset + bytes1,
+		       runtime->dma_area, bytes - bytes1);
+	} else {
+		memcpy(urb->transfer_buffer + offset,
+		       runtime->dma_area + subs->hwptr_done, bytes);
+	}
+	subs->hwptr_done += bytes;
+	if (subs->hwptr_done >= runtime->buffer_size * stride)
+		subs->hwptr_done -= runtime->buffer_size * stride;
+}
+
+static unsigned int copy_to_urb_quirk(struct snd_usb_substream *subs,
+				      struct urb *urb, int stride,
+				      unsigned int bytes)
+{
+	__le32 packet_length;
+	int i;
+
+	/* Put __le32 length descriptor at start of each packet. */
+	for (i = 0; i < urb->number_of_packets; i++) {
+		unsigned int length = urb->iso_frame_desc[i].length;
+		unsigned int offset = urb->iso_frame_desc[i].offset;
+
+		packet_length = cpu_to_le32(length);
+		offset += i * sizeof(packet_length);
+		urb->iso_frame_desc[i].offset = offset;
+		urb->iso_frame_desc[i].length += sizeof(packet_length);
+		memcpy(urb->transfer_buffer + offset,
+		       &packet_length, sizeof(packet_length));
+		copy_to_urb(subs, urb, offset + sizeof(packet_length),
+			    stride, length);
+	}
+	/* Adjust transfer size accordingly. */
+	bytes += urb->number_of_packets * sizeof(packet_length);
+	return bytes;
 }
 
 static void prepare_playback_urb(struct snd_usb_substream *subs,
@@ -1460,27 +1510,17 @@ static void prepare_playback_urb(struct snd_usb_substream *subs,
 		}
 
 		subs->hwptr_done += bytes;
+		if (subs->hwptr_done >= runtime->buffer_size * stride)
+			subs->hwptr_done -= runtime->buffer_size * stride;
 	} else {
 		/* usual PCM */
-		if (subs->hwptr_done + bytes > runtime->buffer_size * stride) {
-			/* err, the transferred area goes over buffer boundary. */
-			unsigned int bytes1 =
-				runtime->buffer_size * stride - subs->hwptr_done;
-			memcpy(urb->transfer_buffer,
-			       runtime->dma_area + subs->hwptr_done, bytes1);
-			memcpy(urb->transfer_buffer + bytes1,
-			       runtime->dma_area, bytes - bytes1);
-		} else {
-			memcpy(urb->transfer_buffer,
-			       runtime->dma_area + subs->hwptr_done, bytes);
-		}
-
-		subs->hwptr_done += bytes;
+		if (!subs->tx_length_quirk)
+			copy_to_urb(subs, urb, 0, stride, bytes);
+		else
+			bytes = copy_to_urb_quirk(subs, urb, stride, bytes);
+			/* bytes is now amount of outgoing data */
 	}
 
-	if (subs->hwptr_done >= runtime->buffer_size * stride)
-		subs->hwptr_done -= runtime->buffer_size * stride;
-
 	/* update delay with exact number of samples queued */
 	runtime->delay = subs->last_delay;
 	runtime->delay += frames;