diff --git a/[refs] b/[refs]
index 83a398f5ad5c..ddf3bce92d21 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: fde854bdaf603a99a80b9545c0aaca9ccd02dd31
+refs/heads/master: 28acb12014fb0c3e1edfdab1b1e3e266cf651550
diff --git a/trunk/sound/usb/endpoint.c b/trunk/sound/usb/endpoint.c
index f487d26f8d40..21049b882ee6 100644
--- a/trunk/sound/usb/endpoint.c
+++ b/trunk/sound/usb/endpoint.c
@@ -1018,15 +1018,18 @@ void snd_usb_handle_sync_urb(struct snd_usb_endpoint *ep,
 		/*
 		 * Iterate through the inbound packet and prepare the lengths
 		 * for the output packet. The OUT packet we are about to send
-		 * will have the same amount of payload bytes than the IN
-		 * packet we just received.
+		 * will have the same amount of payload bytes per stride as the
+		 * IN packet we just received. Since the actual size is scaled
+		 * by the stride, use the sender stride to calculate the length
+		 * in case the number of channels differ between the implicitly
+		 * fed-back endpoint and the synchronizing endpoint.
 		 */
 
 		out_packet->packets = in_ctx->packets;
 		for (i = 0; i < in_ctx->packets; i++) {
 			if (urb->iso_frame_desc[i].status == 0)
 				out_packet->packet_size[i] =
-					urb->iso_frame_desc[i].actual_length / ep->stride;
+					urb->iso_frame_desc[i].actual_length / sender->stride;
 			else
 				out_packet->packet_size[i] = 0;
 		}