usb: wusbcore: combine multiple isoc frames in a single transfer request.

Combine multiple isoc frames in a single transfer request.  This allows
the HWA to take advantage of bursting to deliver data to endpoints
whose logical service interval is less than the minimum wireless USB
service interval of 4ms.  Wireless audio quality is much improved after
this update.

Signed-off-by: Thomas Pugliese <thomas.pugliese@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/wusbcore/wa-xfer.c

@@ -121,6 +121,9 @@ struct wa_seg {
 	struct list_head list_node;	/* for rpipe->req_list */
 	struct wa_xfer *xfer;		/* out xfer */
 	u8 index;			/* which segment we are */
+	int isoc_frame_count;	/* number of isoc frames in this segment. */
+	int isoc_frame_offset;	/* starting frame offset in the xfer URB. */
+	int isoc_size;	/* size of all isoc frames sent by this seg. */
 	enum wa_seg_status status;
 	ssize_t result;			/* bytes xfered or error */
 	struct wa_xfer_hdr xfer_hdr;
@@ -154,12 +157,17 @@ struct wa_xfer {
 	unsigned is_dma:1;
 	size_t seg_size;
 	int result;
+	/* Isoc frame that the current transfer buffer corresponds to. */
+	int dto_isoc_frame_index;
 
 	gfp_t gfp;			/* allocation mask */
 
 	struct wusb_dev *wusb_dev;	/* for activity timestamps */
 };
 
+static void __wa_populate_dto_urb_isoc(struct wa_xfer *xfer,
+	struct wa_seg *seg, int curr_iso_frame);
+
 static inline void wa_xfer_init(struct wa_xfer *xfer)
 {
 	kref_init(&xfer->refcnt);
@@ -462,6 +470,31 @@ error_kmalloc:
 
 }
 
+/*
+ * Calculate the number of isoc frames starting from isoc_frame_offset
+ * that will fit a in transfer segment.
+ */
+static int __wa_seg_calculate_isoc_frame_count(struct wa_xfer *xfer,
+	int isoc_frame_offset, int *total_size)
+{
+	int segment_size = 0, frame_count = 0;
+	int index = isoc_frame_offset;
+
+	while ((index < xfer->urb->number_of_packets)
+		&& ((segment_size + xfer->urb->iso_frame_desc[index].length)
+				<= xfer->seg_size)) {
+		/* this frame fits. count it. */
+		++frame_count;
+		segment_size += xfer->urb->iso_frame_desc[index].length;
+
+		/* move to the next isoc frame. */
+		++index;
+	}
+
+	*total_size = segment_size;
+	return frame_count;
+}
+
 /*
  *
  * @returns < 0 on error, transfer segment request size if ok
@@ -505,8 +538,20 @@ static ssize_t __wa_xfer_setup_sizes(struct wa_xfer *xfer,
 
 	maxpktsize = le16_to_cpu(rpipe->descr.wMaxPacketSize);
 	if ((rpipe->descr.bmAttribute & 0x3) == USB_ENDPOINT_XFER_ISOC) {
+		int index = 0;
+
 		xfer->seg_size = maxpktsize;
-		xfer->segs = urb->number_of_packets;
+		xfer->segs = 0;
+		/*
+		 * loop over urb->number_of_packets to determine how many
+		 * xfer segments will be needed to send the isoc frames.
+		 */
+		while (index < urb->number_of_packets) {
+			int seg_size; /* don't care. */
+			index += __wa_seg_calculate_isoc_frame_count(xfer,
+					index, &seg_size);
+			++xfer->segs;
+		}
 	} else {
 		xfer->seg_size = le16_to_cpu(rpipe->descr.wBlocks)
 			* 1 << (xfer->wa->wa_descr->bRPipeBlockSize - 1);
@@ -523,20 +568,43 @@ static ssize_t __wa_xfer_setup_sizes(struct wa_xfer *xfer,
 		xfer->seg_size = (xfer->seg_size / maxpktsize) * maxpktsize;
 		xfer->segs = DIV_ROUND_UP(urb->transfer_buffer_length,
 						xfer->seg_size);
-		if (xfer->segs >= WA_SEGS_MAX) {
-			dev_err(dev, "BUG? oops, number of segments %zu bigger than %d\n",
-				(urb->transfer_buffer_length/xfer->seg_size),
-				WA_SEGS_MAX);
-			result = -EINVAL;
-			goto error;
-		}
 		if (xfer->segs == 0 && *pxfer_type == WA_XFER_TYPE_CTL)
 			xfer->segs = 1;
 	}
+
+	if (xfer->segs >= WA_SEGS_MAX) {
+		dev_err(dev, "BUG? oops, number of segments %zu bigger than %d\n",
+			(urb->transfer_buffer_length/xfer->seg_size),
+			WA_SEGS_MAX);
+		result = -EINVAL;
+		goto error;
+	}
 error:
 	return result;
 }
 
+static void __wa_setup_isoc_packet_descr(
+		struct wa_xfer_packet_info_hwaiso *packet_desc,
+		struct wa_xfer *xfer,
+		struct wa_seg *seg) {
+	struct usb_iso_packet_descriptor *iso_frame_desc =
+		xfer->urb->iso_frame_desc;
+	int frame_index;
+
+	/* populate isoc packet descriptor. */
+	packet_desc->bPacketType = WA_XFER_ISO_PACKET_INFO;
+	packet_desc->wLength = cpu_to_le16(sizeof(*packet_desc) +
+		(sizeof(packet_desc->PacketLength[0]) *
+			seg->isoc_frame_count));
+	for (frame_index = 0; frame_index < seg->isoc_frame_count;
+		++frame_index) {
+		int offset_index = frame_index + seg->isoc_frame_offset;
+		packet_desc->PacketLength[frame_index] =
+			cpu_to_le16(iso_frame_desc[offset_index].length);
+	}
+}
+
+
 /* Fill in the common request header and xfer-type specific data. */
 static void __wa_xfer_setup_hdr0(struct wa_xfer *xfer,
 				 struct wa_xfer_hdr *xfer_hdr0,
@@ -544,8 +612,9 @@ static void __wa_xfer_setup_hdr0(struct wa_xfer *xfer,
 				 size_t xfer_hdr_size)
 {
 	struct wa_rpipe *rpipe = xfer->ep->hcpriv;
+	struct wa_seg *seg = xfer->seg[0];
 
-	xfer_hdr0 = &xfer->seg[0]->xfer_hdr;
+	xfer_hdr0 = &seg->xfer_hdr;
 	xfer_hdr0->bLength = xfer_hdr_size;
 	xfer_hdr0->bRequestType = xfer_type;
 	xfer_hdr0->wRPipe = rpipe->descr.wRPipeIndex;
@@ -567,19 +636,11 @@ static void __wa_xfer_setup_hdr0(struct wa_xfer *xfer,
 			container_of(xfer_hdr0, struct wa_xfer_hwaiso, hdr);
 		struct wa_xfer_packet_info_hwaiso *packet_desc =
 			((void *)xfer_iso) + xfer_hdr_size;
-		struct usb_iso_packet_descriptor *iso_frame_desc =
-			&(xfer->urb->iso_frame_desc[0]);
+
 		/* populate the isoc section of the transfer request. */
-		xfer_iso->dwNumOfPackets = cpu_to_le32(1);
-		/*
-		 * populate isoc packet descriptor.  This assumes 1
-		 * packet per segment.
-		 */
-		packet_desc->wLength = cpu_to_le16(sizeof(*packet_desc) +
-			sizeof(packet_desc->PacketLength[0]));
-		packet_desc->bPacketType = WA_XFER_ISO_PACKET_INFO;
-		packet_desc->PacketLength[0] =
-			cpu_to_le16(iso_frame_desc->length);
+		xfer_iso->dwNumOfPackets = cpu_to_le32(seg->isoc_frame_count);
+		/* populate isoc packet descriptor. */
+		__wa_setup_isoc_packet_descr(packet_desc, xfer, seg);
 		break;
 	}
 	default:
@@ -608,54 +669,112 @@ static void wa_seg_dto_cb(struct urb *urb)
 	struct wa_rpipe *rpipe;
 	unsigned long flags;
 	unsigned rpipe_ready = 0;
+	int data_send_done = 1, release_dto = 0, holding_dto = 0;
 	u8 done = 0;
+	int result;
 
 	/* free the sg if it was used. */
 	kfree(urb->sg);
 	urb->sg = NULL;
 
+	spin_lock_irqsave(&xfer->lock, flags);
+	wa = xfer->wa;
+	dev = &wa->usb_iface->dev;
+	if (usb_pipeisoc(xfer->urb->pipe)) {
+		xfer->dto_isoc_frame_index += 1;
+		if (xfer->dto_isoc_frame_index < seg->isoc_frame_count) {
+			data_send_done = 0;
+			holding_dto = 1; /* checked in error cases. */
+			/*
+			 * if this is the last isoc frame of the segment, we
+			 * can release DTO after sending this frame.
+			 */
+			if ((xfer->dto_isoc_frame_index + 1) >=
+				seg->isoc_frame_count)
+				release_dto = 1;
+		}
+		dev_dbg(dev, "xfer 0x%08X#%u: isoc frame = %d, holding_dto = %d, release_dto = %d.\n",
+			wa_xfer_id(xfer), seg->index,
+			xfer->dto_isoc_frame_index, holding_dto, release_dto);
+	}
+	spin_unlock_irqrestore(&xfer->lock, flags);
+
 	switch (urb->status) {
 	case 0:
 		spin_lock_irqsave(&xfer->lock, flags);
-		wa = xfer->wa;
-		dev = &wa->usb_iface->dev;
-		dev_dbg(dev, "xfer %p#%u: data out done (%d bytes)\n",
-			xfer, seg->index, urb->actual_length);
-		if (seg->status < WA_SEG_PENDING)
-			seg->status = WA_SEG_PENDING;
-		seg->result = urb->actual_length;
+		seg->result += urb->actual_length;
+		if (data_send_done) {
+			dev_dbg(dev, "xfer 0x%08X#%u: data out done (%zu bytes)\n",
+				wa_xfer_id(xfer), seg->index, seg->result);
+			if (seg->status < WA_SEG_PENDING)
+				seg->status = WA_SEG_PENDING;
+		} else {
+			/* should only hit this for isoc xfers. */
+			/*
+			 * Populate the dto URB with the next isoc frame buffer,
+			 * send the URB and release DTO if we no longer need it.
+			 */
+			 __wa_populate_dto_urb_isoc(xfer, seg,
+				seg->isoc_frame_offset +
+				xfer->dto_isoc_frame_index);
+
+			/* resubmit the URB with the next isoc frame. */
+			result = usb_submit_urb(seg->dto_urb, GFP_ATOMIC);
+			if (result < 0) {
+				dev_err(dev, "xfer 0x%08X#%u: DTO submit failed: %d\n",
+				       wa_xfer_id(xfer), seg->index, result);
+				spin_unlock_irqrestore(&xfer->lock, flags);
+				goto error_dto_submit;
+			}
+		}
 		spin_unlock_irqrestore(&xfer->lock, flags);
+		if (release_dto) {
+			__wa_dto_put(wa);
+			wa_check_for_delayed_rpipes(wa);
+		}
 		break;
 	case -ECONNRESET:	/* URB unlinked; no need to do anything */
 	case -ENOENT:		/* as it was done by the who unlinked us */
+		if (holding_dto) {
+			__wa_dto_put(wa);
+			wa_check_for_delayed_rpipes(wa);
+		}
 		break;
 	default:		/* Other errors ... */
-		spin_lock_irqsave(&xfer->lock, flags);
-		wa = xfer->wa;
-		dev = &wa->usb_iface->dev;
-		rpipe = xfer->ep->hcpriv;
-		dev_dbg(dev, "xfer %p#%u: data out error %d\n",
-			xfer, seg->index, urb->status);
-		if (edc_inc(&wa->nep_edc, EDC_MAX_ERRORS,
-			    EDC_ERROR_TIMEFRAME)){
-			dev_err(dev, "DTO: URB max acceptable errors "
-				"exceeded, resetting device\n");
-			wa_reset_all(wa);
-		}
-		if (seg->status != WA_SEG_ERROR) {
-			seg->status = WA_SEG_ERROR;
-			seg->result = urb->status;
-			xfer->segs_done++;
-			__wa_xfer_abort(xfer);
-			rpipe_ready = rpipe_avail_inc(rpipe);
-			done = __wa_xfer_is_done(xfer);
-		}
-		spin_unlock_irqrestore(&xfer->lock, flags);
-		if (done)
-			wa_xfer_completion(xfer);
-		if (rpipe_ready)
-			wa_xfer_delayed_run(rpipe);
+		dev_err(dev, "xfer 0x%08X#%u: data out error %d\n",
+			wa_xfer_id(xfer), seg->index, urb->status);
+		goto error_default;
+	}
+
+	return;
+
+error_dto_submit:
+error_default:
+	spin_lock_irqsave(&xfer->lock, flags);
+	rpipe = xfer->ep->hcpriv;
+	if (edc_inc(&wa->nep_edc, EDC_MAX_ERRORS,
+		    EDC_ERROR_TIMEFRAME)){
+		dev_err(dev, "DTO: URB max acceptable errors exceeded, resetting device\n");
+		wa_reset_all(wa);
+	}
+	if (seg->status != WA_SEG_ERROR) {
+		seg->status = WA_SEG_ERROR;
+		seg->result = urb->status;
+		xfer->segs_done++;
+		__wa_xfer_abort(xfer);
+		rpipe_ready = rpipe_avail_inc(rpipe);
+		done = __wa_xfer_is_done(xfer);
 	}
+	spin_unlock_irqrestore(&xfer->lock, flags);
+	if (holding_dto) {
+		__wa_dto_put(wa);
+		wa_check_for_delayed_rpipes(wa);
+	}
+	if (done)
+		wa_xfer_completion(xfer);
+	if (rpipe_ready)
+		wa_xfer_delayed_run(rpipe);
+
 }
 
 /*
@@ -686,8 +805,8 @@ static void wa_seg_iso_pack_desc_cb(struct urb *urb)
 		spin_lock_irqsave(&xfer->lock, flags);
 		wa = xfer->wa;
 		dev = &wa->usb_iface->dev;
-		dev_dbg(dev, "iso xfer %p#%u: packet descriptor done\n",
-			xfer, seg->index);
+		dev_dbg(dev, "iso xfer %08X#%u: packet descriptor done\n",
+			wa_xfer_id(xfer), seg->index);
 		if (xfer->is_inbound && seg->status < WA_SEG_PENDING)
 			seg->status = WA_SEG_PENDING;
 		spin_unlock_irqrestore(&xfer->lock, flags);
@@ -700,8 +819,8 @@ static void wa_seg_iso_pack_desc_cb(struct urb *urb)
 		wa = xfer->wa;
 		dev = &wa->usb_iface->dev;
 		rpipe = xfer->ep->hcpriv;
-		pr_err_ratelimited("iso xfer %p#%u: packet descriptor error %d\n",
-				xfer, seg->index, urb->status);
+		pr_err_ratelimited("iso xfer %08X#%u: packet descriptor error %d\n",
+				wa_xfer_id(xfer), seg->index, urb->status);
 		if (edc_inc(&wa->nep_edc, EDC_MAX_ERRORS,
 			    EDC_ERROR_TIMEFRAME)){
 			dev_err(dev, "DTO: URB max acceptable errors exceeded, resetting device\n");
@@ -885,8 +1004,8 @@ static struct scatterlist *wa_xfer_create_subset_sg(struct scatterlist *in_sg,
 /*
  * Populate DMA buffer info for the isoc dto urb.
  */
-static void __wa_populate_dto_urb_iso(struct wa_xfer *xfer,
-	struct wa_seg *seg,	int curr_iso_frame)
+static void __wa_populate_dto_urb_isoc(struct wa_xfer *xfer,
+	struct wa_seg *seg, int curr_iso_frame)
 {
 	/*
 	 * dto urb buffer address and size pulled from
@@ -960,13 +1079,14 @@ static int __wa_populate_dto_urb(struct wa_xfer *xfer,
  */
 static int __wa_xfer_setup_segs(struct wa_xfer *xfer, size_t xfer_hdr_size)
 {
-	int result, cnt;
+	int result, cnt, iso_frame_offset;
 	size_t alloc_size = sizeof(*xfer->seg[0])
 		- sizeof(xfer->seg[0]->xfer_hdr) + xfer_hdr_size;
 	struct usb_device *usb_dev = xfer->wa->usb_dev;
 	const struct usb_endpoint_descriptor *dto_epd = xfer->wa->dto_epd;
 	struct wa_seg *seg;
-	size_t buf_itr, buf_size, buf_itr_size, iso_pkt_descr_size = 0;
+	size_t buf_itr, buf_size, buf_itr_size;
+	int xfer_isoc_frame_offset = 0;
 
 	result = -ENOMEM;
 	xfer->seg = kcalloc(xfer->segs, sizeof(xfer->seg[0]), GFP_ATOMIC);
@@ -974,24 +1094,30 @@ static int __wa_xfer_setup_segs(struct wa_xfer *xfer, size_t xfer_hdr_size)
 		goto error_segs_kzalloc;
 	buf_itr = 0;
 	buf_size = xfer->urb->transfer_buffer_length;
+	iso_frame_offset = 0;
+	for (cnt = 0; cnt < xfer->segs; cnt++) {
+		size_t iso_pkt_descr_size = 0;
+		int seg_isoc_frame_count = 0, seg_isoc_size = 0;
 
-	if (usb_pipeisoc(xfer->urb->pipe)) {
-		/*
-		 * This calculation assumes one isoc packet per xfer segment.
-		 * It will need to be updated if this changes.
-		 */
-		iso_pkt_descr_size = sizeof(struct wa_xfer_packet_info_hwaiso) +
-			sizeof(__le16);
-		alloc_size += iso_pkt_descr_size;
-	}
+		if (usb_pipeisoc(xfer->urb->pipe)) {
+			seg_isoc_frame_count =
+				__wa_seg_calculate_isoc_frame_count(xfer,
+					xfer_isoc_frame_offset, &seg_isoc_size);
 
-	for (cnt = 0; cnt < xfer->segs; cnt++) {
-		seg = xfer->seg[cnt] = kmalloc(alloc_size, GFP_ATOMIC);
+			iso_pkt_descr_size =
+				sizeof(struct wa_xfer_packet_info_hwaiso) +
+				(seg_isoc_frame_count * sizeof(__le16));
+		}
+		seg = xfer->seg[cnt] = kmalloc(alloc_size + iso_pkt_descr_size,
+						GFP_ATOMIC);
 		if (seg == NULL)
 			goto error_seg_kmalloc;
 		wa_seg_init(seg);
 		seg->xfer = xfer;
 		seg->index = cnt;
+		seg->isoc_frame_count = seg_isoc_frame_count;
+		seg->isoc_frame_offset = xfer_isoc_frame_offset;
+		seg->isoc_size = seg_isoc_size;
 		usb_fill_bulk_urb(&seg->tr_urb, usb_dev,
 				  usb_sndbulkpipe(usb_dev,
 						  dto_epd->bEndpointAddress),
@@ -1029,8 +1155,16 @@ static int __wa_xfer_setup_segs(struct wa_xfer *xfer, size_t xfer_hdr_size)
 					iso_pkt_descr_size,
 					wa_seg_iso_pack_desc_cb, seg);
 
-				/* fill in the xfer buffer information. */
-				__wa_populate_dto_urb_iso(xfer, seg, cnt);
+				/*
+				 * Fill in the xfer buffer information for the
+				 * first isoc frame.  Subsequent frames in this
+				 * segment will be filled in and sent from the
+				 * DTO completion routine, if needed.
+				 */
+				__wa_populate_dto_urb_isoc(xfer, seg,
+					xfer_isoc_frame_offset);
+				/* adjust starting frame offset for next seg. */
+				xfer_isoc_frame_offset += seg_isoc_frame_count;
 			} else {
 				/* fill in the xfer buffer information. */
 				result = __wa_populate_dto_urb(xfer, seg,
@@ -1099,28 +1233,23 @@ static int __wa_xfer_setup(struct wa_xfer *xfer, struct urb *urb)
 	xfer_hdr = xfer_hdr0;
 	if (xfer_type == WA_XFER_TYPE_ISO) {
 		xfer_hdr0->dwTransferLength =
-			cpu_to_le32(xfer->urb->iso_frame_desc[0].length);
+			cpu_to_le32(xfer->seg[0]->isoc_size);
 		for (cnt = 1; cnt < xfer->segs; cnt++) {
-			struct usb_iso_packet_descriptor *iso_frame_desc =
-				&(xfer->urb->iso_frame_desc[cnt]);
 			struct wa_xfer_packet_info_hwaiso *packet_desc;
+			struct wa_seg *seg = xfer->seg[cnt];
 
-			xfer_hdr = &xfer->seg[cnt]->xfer_hdr;
+			xfer_hdr = &seg->xfer_hdr;
 			packet_desc = ((void *)xfer_hdr) + xfer_hdr_size;
 			/*
-			 * Copy values from the 0th header and isoc packet
-			 * descriptor.  Segment specific values are set below.
+			 * Copy values from the 0th header. Segment specific
+			 * values are set below.
 			 */
-			memcpy(xfer_hdr, xfer_hdr0,
-				xfer_hdr_size + sizeof(*packet_desc));
+			memcpy(xfer_hdr, xfer_hdr0, xfer_hdr_size);
 			xfer_hdr->bTransferSegment = cnt;
 			xfer_hdr->dwTransferLength =
-				cpu_to_le32(iso_frame_desc->length);
-			/* populate isoc packet descriptor length. */
-			packet_desc->PacketLength[0] =
-				cpu_to_le16(iso_frame_desc->length);
-
-			xfer->seg[cnt]->status = WA_SEG_READY;
+				cpu_to_le32(seg->isoc_size);
+			__wa_setup_isoc_packet_descr(packet_desc, xfer, seg);
+			seg->status = WA_SEG_READY;
 		}
 	} else {
 		transfer_size = urb->transfer_buffer_length;
@@ -1175,6 +1304,13 @@ static int __wa_seg_submit(struct wa_rpipe *rpipe, struct wa_xfer *xfer,
 			       __func__, xfer, seg->index, result);
 			goto error_iso_pack_desc_submit;
 		}
+		xfer->dto_isoc_frame_index = 0;
+		/*
+		 * If this segment contains more than one isoc frame, hold
+		 * onto the dto resource until we send all frames.
+		 */
+		if (seg->isoc_frame_count > 1)
+			*dto_done = 0;
 	}
 	/* submit the out data if this is an out request. */
 	if (seg->dto_urb) {
@@ -1196,6 +1332,7 @@ error_iso_pack_desc_submit:
 error_seg_submit:
 	seg->status = WA_SEG_ERROR;
 	seg->result = result;
+	*dto_done = 1;
 	return result;
 }
 
@@ -1306,9 +1443,6 @@ static int __wa_xfer_submit(struct wa_xfer *xfer)
 		available = atomic_read(&rpipe->segs_available);
 		empty = list_empty(&rpipe->seg_list);
 		seg = xfer->seg[cnt];
-		dev_dbg(dev, "xfer %p ID 0x%08X#%u: available %u empty %u (%s)\n",
-			xfer, wa_xfer_id(xfer), cnt, available, empty,
-			available == 0 || !empty ? "delayed" : "submitted");
 		if (available && empty) {
 			/*
 			 * Only attempt to acquire DTO if we have a segment
@@ -1319,6 +1453,9 @@ static int __wa_xfer_submit(struct wa_xfer *xfer)
 				delay_seg = 0;
 				result = __wa_seg_submit(rpipe, xfer, seg,
 							&dto_done);
+				dev_dbg(dev, "xfer %p ID 0x%08X#%u: available %u empty %u submitted\n",
+					xfer, wa_xfer_id(xfer), cnt, available,
+					empty);
 				if (dto_done)
 					__wa_dto_put(rpipe->wa);
 
@@ -1330,6 +1467,8 @@ static int __wa_xfer_submit(struct wa_xfer *xfer)
 		}
 
 		if (delay_seg) {
+			dev_dbg(dev, "xfer %p ID 0x%08X#%u: available %u empty %u delayed\n",
+				xfer, wa_xfer_id(xfer), cnt, available,  empty);
 			seg->status = WA_SEG_DELAYED;
 			list_add_tail(&seg->list_node, &rpipe->seg_list);
 		}
@@ -2031,29 +2170,19 @@ static void wa_process_iso_packet_status(struct wahc *wa, struct urb *urb)
 {
 	struct device *dev = &wa->usb_iface->dev;
 	struct wa_xfer_packet_status_hwaiso *packet_status;
+	struct wa_xfer_packet_status_len_hwaiso *status_array;
 	struct wa_xfer *xfer;
 	unsigned long flags;
 	struct wa_seg *seg;
 	struct wa_rpipe *rpipe;
 	unsigned done = 0;
-	unsigned rpipe_ready = 0;
-	const int expected_size = sizeof(*packet_status) +
-				sizeof(packet_status->PacketStatus[0]);
+	unsigned rpipe_ready = 0, seg_index;
+	int expected_size;
 
 	/* We have a xfer result buffer; check it */
 	dev_dbg(dev, "DTI: isoc packet status %d bytes at %p\n",
 		urb->actual_length, urb->transfer_buffer);
-	if (urb->actual_length != expected_size) {
-		dev_err(dev, "DTI Error: isoc packet status--bad urb length (%d bytes vs %d needed)\n",
-			urb->actual_length, expected_size);
-		goto error_parse_buffer;
-	}
 	packet_status = (struct wa_xfer_packet_status_hwaiso *)(wa->dti_buf);
-	if (le16_to_cpu(packet_status->wLength) != expected_size) {
-		dev_err(dev, "DTI Error: isoc packet status--bad length %u\n",
-			le16_to_cpu(packet_status->wLength));
-		goto error_parse_buffer;
-	}
 	if (packet_status->bPacketType != WA_XFER_ISO_PACKET_STATUS) {
 		dev_err(dev, "DTI Error: isoc packet status--bad type 0x%02x\n",
 			packet_status->bPacketType);
@@ -2070,13 +2199,28 @@ static void wa_process_iso_packet_status(struct wahc *wa, struct urb *urb)
 		goto error_bad_seg;
 	seg = xfer->seg[wa->dti_isoc_xfer_seg];
 	rpipe = xfer->ep->hcpriv;
-
-	/* set urb isoc packet status and length. */
-	xfer->urb->iso_frame_desc[seg->index].status =
-		wa_xfer_status_to_errno(
-		le16_to_cpu(packet_status->PacketStatus[0].PacketStatus));
-	xfer->urb->iso_frame_desc[seg->index].actual_length =
-		le16_to_cpu(packet_status->PacketStatus[0].PacketLength);
+	expected_size = sizeof(*packet_status) +
+			(sizeof(packet_status->PacketStatus[0]) *
+			seg->isoc_frame_count);
+	if (urb->actual_length != expected_size) {
+		dev_err(dev, "DTI Error: isoc packet status--bad urb length (%d bytes vs %d needed)\n",
+			urb->actual_length, expected_size);
+		goto error_bad_seg;
+	}
+	if (le16_to_cpu(packet_status->wLength) != expected_size) {
+		dev_err(dev, "DTI Error: isoc packet status--bad length %u\n",
+			le16_to_cpu(packet_status->wLength));
+		goto error_bad_seg;
+	}
+	/* isoc packet status and lengths back xfer urb. */
+	status_array = packet_status->PacketStatus;
+	for (seg_index = 0; seg_index < seg->isoc_frame_count; ++seg_index) {
+		xfer->urb->iso_frame_desc[seg->index].status =
+			wa_xfer_status_to_errno(
+			le16_to_cpu(status_array[seg_index].PacketStatus));
+		xfer->urb->iso_frame_desc[seg->index].actual_length =
+			le16_to_cpu(status_array[seg_index].PacketLength);
+	}
 
 	if (!xfer->is_inbound) {
 		/* OUT transfer, complete it -- */