1 files changed, 236 insertions, 142 deletions

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index 6bfbd80ec2b9..53c2e296467f 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -178,7 +178,7 @@ static void inc_deq(struct xhci_hcd *xhci, struct xhci_ring *ring)
 			if (ring->type == TYPE_EVENT &&
 					last_trb_on_last_seg(xhci, ring,
 						ring->deq_seg, ring->dequeue)) {
-				ring->cycle_state = (ring->cycle_state ? 0 : 1);
+				ring->cycle_state ^= 1;
 			}
 			ring->deq_seg = ring->deq_seg->next;
 			ring->dequeue = ring->deq_seg->trbs;
@@ -726,7 +726,7 @@ static void xhci_stop_watchdog_timer_in_irq(struct xhci_hcd *xhci,
 
 /* Must be called with xhci->lock held in interrupt context */
 static void xhci_giveback_urb_in_irq(struct xhci_hcd *xhci,
-		struct xhci_td *cur_td, int status, char *adjective)
+		struct xhci_td *cur_td, int status)
 {
 	struct usb_hcd *hcd;
 	struct urb	*urb;
@@ -765,10 +765,9 @@ static void xhci_giveback_urb_in_irq(struct xhci_hcd *xhci,
  *  2. Otherwise, we turn all the TRBs in the TD into No-op TRBs (with the chain
  *     bit cleared) so that the HW will skip over them.
  */
-static void handle_stopped_endpoint(struct xhci_hcd *xhci,
+static void xhci_handle_cmd_stop_ep(struct xhci_hcd *xhci, int slot_id,
 		union xhci_trb *trb, struct xhci_event_cmd *event)
 {
-	unsigned int slot_id;
 	unsigned int ep_index;
 	struct xhci_virt_device *virt_dev;
 	struct xhci_ring *ep_ring;
@@ -779,10 +778,7 @@ static void handle_stopped_endpoint(struct xhci_hcd *xhci,
 
 	struct xhci_dequeue_state deq_state;
 
-	if (unlikely(TRB_TO_SUSPEND_PORT(
-			     le32_to_cpu(xhci->cmd_ring->dequeue->generic.field[3])))) {
-		slot_id = TRB_TO_SLOT_ID(
-			le32_to_cpu(xhci->cmd_ring->dequeue->generic.field[3]));
+	if (unlikely(TRB_TO_SUSPEND_PORT(le32_to_cpu(trb->generic.field[3])))) {
 		virt_dev = xhci->devs[slot_id];
 		if (virt_dev)
 			handle_cmd_in_cmd_wait_list(xhci, virt_dev,
@@ -795,7 +791,6 @@ static void handle_stopped_endpoint(struct xhci_hcd *xhci,
 	}
 
 	memset(&deq_state, 0, sizeof(deq_state));
-	slot_id = TRB_TO_SLOT_ID(le32_to_cpu(trb->generic.field[3]));
 	ep_index = TRB_TO_EP_INDEX(le32_to_cpu(trb->generic.field[3]));
 	ep = &xhci->devs[slot_id]->eps[ep_index];
 
@@ -891,7 +886,7 @@ remove_finished_td:
 		/* Doesn't matter what we pass for status, since the core will
 		 * just overwrite it (because the URB has been unlinked).
 		 */
-		xhci_giveback_urb_in_irq(xhci, cur_td, 0, "cancelled");
+		xhci_giveback_urb_in_irq(xhci, cur_td, 0);
 
 		/* Stop processing the cancelled list if the watchdog timer is
 		 * running.
@@ -1001,7 +996,7 @@ void xhci_stop_endpoint_command_watchdog(unsigned long arg)
 				if (!list_empty(&cur_td->cancelled_td_list))
 					list_del_init(&cur_td->cancelled_td_list);
 				xhci_giveback_urb_in_irq(xhci, cur_td,
-						-ESHUTDOWN, "killed");
+						-ESHUTDOWN);
 			}
 			while (!list_empty(&temp_ep->cancelled_td_list)) {
 				cur_td = list_first_entry(
@@ -1010,7 +1005,7 @@ void xhci_stop_endpoint_command_watchdog(unsigned long arg)
 						cancelled_td_list);
 				list_del_init(&cur_td->cancelled_td_list);
 				xhci_giveback_urb_in_irq(xhci, cur_td,
-						-ESHUTDOWN, "killed");
+						-ESHUTDOWN);
 			}
 		}
 	}
@@ -1077,11 +1072,9 @@ static void update_ring_for_set_deq_completion(struct xhci_hcd *xhci,
  * endpoint doorbell to restart the ring, but only if there aren't more
  * cancellations pending.
  */
-static void handle_set_deq_completion(struct xhci_hcd *xhci,
-		struct xhci_event_cmd *event,
-		union xhci_trb *trb)
+static void xhci_handle_cmd_set_deq(struct xhci_hcd *xhci, int slot_id,
+		union xhci_trb *trb, u32 cmd_comp_code)
 {
-	unsigned int slot_id;
 	unsigned int ep_index;
 	unsigned int stream_id;
 	struct xhci_ring *ep_ring;
@@ -1089,7 +1082,6 @@ static void handle_set_deq_completion(struct xhci_hcd *xhci,
 	struct xhci_ep_ctx *ep_ctx;
 	struct xhci_slot_ctx *slot_ctx;
 
-	slot_id = TRB_TO_SLOT_ID(le32_to_cpu(trb->generic.field[3]));
 	ep_index = TRB_TO_EP_INDEX(le32_to_cpu(trb->generic.field[3]));
 	stream_id = TRB_TO_STREAM_ID(le32_to_cpu(trb->generic.field[2]));
 	dev = xhci->devs[slot_id];
@@ -1107,11 +1099,11 @@ static void handle_set_deq_completion(struct xhci_hcd *xhci,
 	ep_ctx = xhci_get_ep_ctx(xhci, dev->out_ctx, ep_index);
 	slot_ctx = xhci_get_slot_ctx(xhci, dev->out_ctx);
 
-	if (GET_COMP_CODE(le32_to_cpu(event->status)) != COMP_SUCCESS) {
+	if (cmd_comp_code != COMP_SUCCESS) {
 		unsigned int ep_state;
 		unsigned int slot_state;
 
-		switch (GET_COMP_CODE(le32_to_cpu(event->status))) {
+		switch (cmd_comp_code) {
 		case COMP_TRB_ERR:
 			xhci_warn(xhci, "WARN Set TR Deq Ptr cmd invalid because "
 					"of stream ID configuration\n");
@@ -1134,7 +1126,7 @@ static void handle_set_deq_completion(struct xhci_hcd *xhci,
 		default:
 			xhci_warn(xhci, "WARN Set TR Deq Ptr cmd with unknown "
 					"completion code of %u.\n",
-				  GET_COMP_CODE(le32_to_cpu(event->status)));
+				  cmd_comp_code);
 			break;
 		}
 		/* OK what do we do now?  The endpoint state is hosed, and we
@@ -1171,21 +1163,17 @@ static void handle_set_deq_completion(struct xhci_hcd *xhci,
 	ring_doorbell_for_active_rings(xhci, slot_id, ep_index);
 }
 
-static void handle_reset_ep_completion(struct xhci_hcd *xhci,
-		struct xhci_event_cmd *event,
-		union xhci_trb *trb)
+static void xhci_handle_cmd_reset_ep(struct xhci_hcd *xhci, int slot_id,
+		union xhci_trb *trb, u32 cmd_comp_code)
 {
-	int slot_id;
 	unsigned int ep_index;
 
-	slot_id = TRB_TO_SLOT_ID(le32_to_cpu(trb->generic.field[3]));
 	ep_index = TRB_TO_EP_INDEX(le32_to_cpu(trb->generic.field[3]));
 	/* This command will only fail if the endpoint wasn't halted,
 	 * but we don't care.
 	 */
 	xhci_dbg_trace(xhci, trace_xhci_dbg_reset_ep,
-		"Ignoring reset ep completion code of %u",
-		 GET_COMP_CODE(le32_to_cpu(event->status)));
+		"Ignoring reset ep completion code of %u", cmd_comp_code);
 
 	/* HW with the reset endpoint quirk needs to have a configure endpoint
 	 * command complete before the endpoint can be used.  Queue that here
@@ -1386,21 +1374,149 @@ static int handle_stopped_cmd_ring(struct xhci_hcd *xhci,
 	return cur_trb_is_good;
 }
 
+static void xhci_handle_cmd_enable_slot(struct xhci_hcd *xhci, int slot_id,
+		u32 cmd_comp_code)
+{
+	if (cmd_comp_code == COMP_SUCCESS)
+		xhci->slot_id = slot_id;
+	else
+		xhci->slot_id = 0;
+	complete(&xhci->addr_dev);
+}
+
+static void xhci_handle_cmd_disable_slot(struct xhci_hcd *xhci, int slot_id)
+{
+	struct xhci_virt_device *virt_dev;
+
+	virt_dev = xhci->devs[slot_id];
+	if (!virt_dev)
+		return;
+	if (xhci->quirks & XHCI_EP_LIMIT_QUIRK)
+		/* Delete default control endpoint resources */
+		xhci_free_device_endpoint_resources(xhci, virt_dev, true);
+	xhci_free_virt_device(xhci, slot_id);
+}
+
+static void xhci_handle_cmd_config_ep(struct xhci_hcd *xhci, int slot_id,
+		struct xhci_event_cmd *event, u32 cmd_comp_code)
+{
+	struct xhci_virt_device *virt_dev;
+	struct xhci_input_control_ctx *ctrl_ctx;
+	unsigned int ep_index;
+	unsigned int ep_state;
+	u32 add_flags, drop_flags;
+
+	virt_dev = xhci->devs[slot_id];
+	if (handle_cmd_in_cmd_wait_list(xhci, virt_dev, event))
+		return;
+	/*
+	 * Configure endpoint commands can come from the USB core
+	 * configuration or alt setting changes, or because the HW
+	 * needed an extra configure endpoint command after a reset
+	 * endpoint command or streams were being configured.
+	 * If the command was for a halted endpoint, the xHCI driver
+	 * is not waiting on the configure endpoint command.
+	 */
+	ctrl_ctx = xhci_get_input_control_ctx(xhci, virt_dev->in_ctx);
+	if (!ctrl_ctx) {
+		xhci_warn(xhci, "Could not get input context, bad type.\n");
+		return;
+	}
+
+	add_flags = le32_to_cpu(ctrl_ctx->add_flags);
+	drop_flags = le32_to_cpu(ctrl_ctx->drop_flags);
+	/* Input ctx add_flags are the endpoint index plus one */
+	ep_index = xhci_last_valid_endpoint(add_flags) - 1;
+
+	/* A usb_set_interface() call directly after clearing a halted
+	 * condition may race on this quirky hardware.  Not worth
+	 * worrying about, since this is prototype hardware.  Not sure
+	 * if this will work for streams, but streams support was
+	 * untested on this prototype.
+	 */
+	if (xhci->quirks & XHCI_RESET_EP_QUIRK &&
+			ep_index != (unsigned int) -1 &&
+			add_flags - SLOT_FLAG == drop_flags) {
+		ep_state = virt_dev->eps[ep_index].ep_state;
+		if (!(ep_state & EP_HALTED))
+			goto bandwidth_change;
+		xhci_dbg_trace(xhci, trace_xhci_dbg_quirks,
+				"Completed config ep cmd - "
+				"last ep index = %d, state = %d",
+				ep_index, ep_state);
+		/* Clear internal halted state and restart ring(s) */
+		virt_dev->eps[ep_index].ep_state &= ~EP_HALTED;
+		ring_doorbell_for_active_rings(xhci, slot_id, ep_index);
+		return;
+	}
+bandwidth_change:
+	xhci_dbg_trace(xhci,  trace_xhci_dbg_context_change,
+			"Completed config ep cmd");
+	virt_dev->cmd_status = cmd_comp_code;
+	complete(&virt_dev->cmd_completion);
+	return;
+}
+
+static void xhci_handle_cmd_eval_ctx(struct xhci_hcd *xhci, int slot_id,
+		struct xhci_event_cmd *event, u32 cmd_comp_code)
+{
+	struct xhci_virt_device *virt_dev;
+
+	virt_dev = xhci->devs[slot_id];
+	if (handle_cmd_in_cmd_wait_list(xhci, virt_dev, event))
+		return;
+	virt_dev->cmd_status = cmd_comp_code;
+	complete(&virt_dev->cmd_completion);
+}
+
+static void xhci_handle_cmd_addr_dev(struct xhci_hcd *xhci, int slot_id,
+		u32 cmd_comp_code)
+{
+	xhci->devs[slot_id]->cmd_status = cmd_comp_code;
+	complete(&xhci->addr_dev);
+}
+
+static void xhci_handle_cmd_reset_dev(struct xhci_hcd *xhci, int slot_id,
+		struct xhci_event_cmd *event)
+{
+	struct xhci_virt_device *virt_dev;
+
+	xhci_dbg(xhci, "Completed reset device command.\n");
+	virt_dev = xhci->devs[slot_id];
+	if (virt_dev)
+		handle_cmd_in_cmd_wait_list(xhci, virt_dev, event);
+	else
+		xhci_warn(xhci, "Reset device command completion "
+				"for disabled slot %u\n", slot_id);
+}
+
+static void xhci_handle_cmd_nec_get_fw(struct xhci_hcd *xhci,
+		struct xhci_event_cmd *event)
+{
+	if (!(xhci->quirks & XHCI_NEC_HOST)) {
+		xhci->error_bitmask |= 1 << 6;
+		return;
+	}
+	xhci_dbg_trace(xhci, trace_xhci_dbg_quirks,
+			"NEC firmware version %2x.%02x",
+			NEC_FW_MAJOR(le32_to_cpu(event->status)),
+			NEC_FW_MINOR(le32_to_cpu(event->status)));
+}
+
 static void handle_cmd_completion(struct xhci_hcd *xhci,
 		struct xhci_event_cmd *event)
 {
 	int slot_id = TRB_TO_SLOT_ID(le32_to_cpu(event->flags));
 	u64 cmd_dma;
 	dma_addr_t cmd_dequeue_dma;
-	struct xhci_input_control_ctx *ctrl_ctx;
-	struct xhci_virt_device *virt_dev;
-	unsigned int ep_index;
-	struct xhci_ring *ep_ring;
-	unsigned int ep_state;
+	u32 cmd_comp_code;
+	union xhci_trb *cmd_trb;
+	u32 cmd_type;
 
 	cmd_dma = le64_to_cpu(event->cmd_trb);
+	cmd_trb = xhci->cmd_ring->dequeue;
 	cmd_dequeue_dma = xhci_trb_virt_to_dma(xhci->cmd_ring->deq_seg,
-			xhci->cmd_ring->dequeue);
+			cmd_trb);
 	/* Is the command ring deq ptr out of sync with the deq seg ptr? */
 	if (cmd_dequeue_dma == 0) {
 		xhci->error_bitmask |= 1 << 4;
@@ -1412,19 +1528,17 @@ static void handle_cmd_completion(struct xhci_hcd *xhci,
 		return;
 	}
 
-	trace_xhci_cmd_completion(&xhci->cmd_ring->dequeue->generic,
-					(struct xhci_generic_trb *) event);
+	trace_xhci_cmd_completion(cmd_trb, (struct xhci_generic_trb *) event);
 
-	if ((GET_COMP_CODE(le32_to_cpu(event->status)) == COMP_CMD_ABORT) ||
-		(GET_COMP_CODE(le32_to_cpu(event->status)) == COMP_CMD_STOP)) {
+	cmd_comp_code = GET_COMP_CODE(le32_to_cpu(event->status));
+	if (cmd_comp_code == COMP_CMD_ABORT || cmd_comp_code == COMP_CMD_STOP) {
 		/* If the return value is 0, we think the trb pointed by
 		 * command ring dequeue pointer is a good trb. The good
 		 * trb means we don't want to cancel the trb, but it have
 		 * been stopped by host. So we should handle it normally.
 		 * Otherwise, driver should invoke inc_deq() and return.
 		 */
-		if (handle_stopped_cmd_ring(xhci,
-				GET_COMP_CODE(le32_to_cpu(event->status)))) {
+		if (handle_stopped_cmd_ring(xhci, cmd_comp_code)) {
 			inc_deq(xhci, xhci->cmd_ring);
 			return;
 		}
@@ -1436,117 +1550,47 @@ static void handle_cmd_completion(struct xhci_hcd *xhci,
 			return;
 	}
 
-	switch (le32_to_cpu(xhci->cmd_ring->dequeue->generic.field[3])
-		& TRB_TYPE_BITMASK) {
-	case TRB_TYPE(TRB_ENABLE_SLOT):
-		if (GET_COMP_CODE(le32_to_cpu(event->status)) == COMP_SUCCESS)
-			xhci->slot_id = slot_id;
-		else
-			xhci->slot_id = 0;
-		complete(&xhci->addr_dev);
+	cmd_type = TRB_FIELD_TO_TYPE(le32_to_cpu(cmd_trb->generic.field[3]));
+	switch (cmd_type) {
+	case TRB_ENABLE_SLOT:
+		xhci_handle_cmd_enable_slot(xhci, slot_id, cmd_comp_code);
 		break;
-	case TRB_TYPE(TRB_DISABLE_SLOT):
-		if (xhci->devs[slot_id]) {
-			if (xhci->quirks & XHCI_EP_LIMIT_QUIRK)
-				/* Delete default control endpoint resources */
-				xhci_free_device_endpoint_resources(xhci,
-						xhci->devs[slot_id], true);
-			xhci_free_virt_device(xhci, slot_id);
-		}
+	case TRB_DISABLE_SLOT:
+		xhci_handle_cmd_disable_slot(xhci, slot_id);
 		break;
-	case TRB_TYPE(TRB_CONFIG_EP):
-		virt_dev = xhci->devs[slot_id];
-		if (handle_cmd_in_cmd_wait_list(xhci, virt_dev, event))
-			break;
-		/*
-		 * Configure endpoint commands can come from the USB core
-		 * configuration or alt setting changes, or because the HW
-		 * needed an extra configure endpoint command after a reset
-		 * endpoint command or streams were being configured.
-		 * If the command was for a halted endpoint, the xHCI driver
-		 * is not waiting on the configure endpoint command.
-		 */
-		ctrl_ctx = xhci_get_input_control_ctx(xhci,
-				virt_dev->in_ctx);
-		if (!ctrl_ctx) {
-			xhci_warn(xhci, "Could not get input context, bad type.\n");
-			break;
-		}
-		/* Input ctx add_flags are the endpoint index plus one */
-		ep_index = xhci_last_valid_endpoint(le32_to_cpu(ctrl_ctx->add_flags)) - 1;
-		/* A usb_set_interface() call directly after clearing a halted
-		 * condition may race on this quirky hardware.  Not worth
-		 * worrying about, since this is prototype hardware.  Not sure
-		 * if this will work for streams, but streams support was
-		 * untested on this prototype.
-		 */
-		if (xhci->quirks & XHCI_RESET_EP_QUIRK &&
-				ep_index != (unsigned int) -1 &&
-		    le32_to_cpu(ctrl_ctx->add_flags) - SLOT_FLAG ==
-		    le32_to_cpu(ctrl_ctx->drop_flags)) {
-			ep_ring = xhci->devs[slot_id]->eps[ep_index].ring;
-			ep_state = xhci->devs[slot_id]->eps[ep_index].ep_state;
-			if (!(ep_state & EP_HALTED))
-				goto bandwidth_change;
-			xhci_dbg_trace(xhci, trace_xhci_dbg_quirks,
-					"Completed config ep cmd - "
-					"last ep index = %d, state = %d",
-					ep_index, ep_state);
-			/* Clear internal halted state and restart ring(s) */
-			xhci->devs[slot_id]->eps[ep_index].ep_state &=
-				~EP_HALTED;
-			ring_doorbell_for_active_rings(xhci, slot_id, ep_index);
-			break;
-		}
-bandwidth_change:
-		xhci_dbg_trace(xhci,  trace_xhci_dbg_context_change,
-				"Completed config ep cmd");
-		xhci->devs[slot_id]->cmd_status =
-			GET_COMP_CODE(le32_to_cpu(event->status));
-		complete(&xhci->devs[slot_id]->cmd_completion);
+	case TRB_CONFIG_EP:
+		xhci_handle_cmd_config_ep(xhci, slot_id, event, cmd_comp_code);
 		break;
-	case TRB_TYPE(TRB_EVAL_CONTEXT):
-		virt_dev = xhci->devs[slot_id];
-		if (handle_cmd_in_cmd_wait_list(xhci, virt_dev, event))
-			break;
-		xhci->devs[slot_id]->cmd_status = GET_COMP_CODE(le32_to_cpu(event->status));
-		complete(&xhci->devs[slot_id]->cmd_completion);
+	case TRB_EVAL_CONTEXT:
+		xhci_handle_cmd_eval_ctx(xhci, slot_id, event, cmd_comp_code);
 		break;
-	case TRB_TYPE(TRB_ADDR_DEV):
-		xhci->devs[slot_id]->cmd_status = GET_COMP_CODE(le32_to_cpu(event->status));
-		complete(&xhci->addr_dev);
+	case TRB_ADDR_DEV:
+		xhci_handle_cmd_addr_dev(xhci, slot_id, cmd_comp_code);
 		break;
-	case TRB_TYPE(TRB_STOP_RING):
-		handle_stopped_endpoint(xhci, xhci->cmd_ring->dequeue, event);
+	case TRB_STOP_RING:
+		WARN_ON(slot_id != TRB_TO_SLOT_ID(
+				le32_to_cpu(cmd_trb->generic.field[3])));
+		xhci_handle_cmd_stop_ep(xhci, slot_id, cmd_trb, event);
 		break;
-	case TRB_TYPE(TRB_SET_DEQ):
-		handle_set_deq_completion(xhci, event, xhci->cmd_ring->dequeue);
+	case TRB_SET_DEQ:
+		WARN_ON(slot_id != TRB_TO_SLOT_ID(
+				le32_to_cpu(cmd_trb->generic.field[3])));
+		xhci_handle_cmd_set_deq(xhci, slot_id, cmd_trb, cmd_comp_code);
 		break;
-	case TRB_TYPE(TRB_CMD_NOOP):
+	case TRB_CMD_NOOP:
 		break;
-	case TRB_TYPE(TRB_RESET_EP):
-		handle_reset_ep_completion(xhci, event, xhci->cmd_ring->dequeue);
+	case TRB_RESET_EP:
+		WARN_ON(slot_id != TRB_TO_SLOT_ID(
+				le32_to_cpu(cmd_trb->generic.field[3])));
+		xhci_handle_cmd_reset_ep(xhci, slot_id, cmd_trb, cmd_comp_code);
 		break;
-	case TRB_TYPE(TRB_RESET_DEV):
-		xhci_dbg(xhci, "Completed reset device command.\n");
-		slot_id = TRB_TO_SLOT_ID(
-			le32_to_cpu(xhci->cmd_ring->dequeue->generic.field[3]));
-		virt_dev = xhci->devs[slot_id];
-		if (virt_dev)
-			handle_cmd_in_cmd_wait_list(xhci, virt_dev, event);
-		else
-			xhci_warn(xhci, "Reset device command completion "
-					"for disabled slot %u\n", slot_id);
+	case TRB_RESET_DEV:
+		WARN_ON(slot_id != TRB_TO_SLOT_ID(
+				le32_to_cpu(cmd_trb->generic.field[3])));
+		xhci_handle_cmd_reset_dev(xhci, slot_id, event);
 		break;
-	case TRB_TYPE(TRB_NEC_GET_FW):
-		if (!(xhci->quirks & XHCI_NEC_HOST)) {
-			xhci->error_bitmask |= 1 << 6;
-			break;
-		}
-		xhci_dbg_trace(xhci, trace_xhci_dbg_quirks,
-			"NEC firmware version %2x.%02x",
-			 NEC_FW_MAJOR(le32_to_cpu(event->status)),
-			 NEC_FW_MINOR(le32_to_cpu(event->status)));
+	case TRB_NEC_GET_FW:
+		xhci_handle_cmd_nec_get_fw(xhci, event);
 		break;
 	default:
 		/* Skip over unknown commands on the event ring */
@@ -2929,8 +2973,58 @@ static int prepare_ring(struct xhci_hcd *xhci, struct xhci_ring *ep_ring,
 	}
 
 	while (1) {
-		if (room_on_ring(xhci, ep_ring, num_trbs))
-			break;
+		if (room_on_ring(xhci, ep_ring, num_trbs)) {
+			union xhci_trb *trb = ep_ring->enqueue;
+			unsigned int usable = ep_ring->enq_seg->trbs +
+					TRBS_PER_SEGMENT - 1 - trb;
+			u32 nop_cmd;
+
+			/*
+			 * Section 4.11.7.1 TD Fragments states that a link
+			 * TRB must only occur at the boundary between
+			 * data bursts (eg 512 bytes for 480M).
+			 * While it is possible to split a large fragment
+			 * we don't know the size yet.
+			 * Simplest solution is to fill the trb before the
+			 * LINK with nop commands.
+			 */
+			if (num_trbs == 1 || num_trbs <= usable || usable == 0)
+				break;
+
+			if (ep_ring->type != TYPE_BULK)
+				/*
+				 * While isoc transfers might have a buffer that
+				 * crosses a 64k boundary it is unlikely.
+				 * Since we can't add NOPs without generating
+				 * gaps in the traffic just hope it never
+				 * happens at the end of the ring.
+				 * This could be fixed by writing a LINK TRB
+				 * instead of the first NOP - however the
+				 * TRB_TYPE_LINK_LE32() calls would all need
+				 * changing to check the ring length.
+				 */
+				break;
+
+			if (num_trbs >= TRBS_PER_SEGMENT) {
+				xhci_err(xhci, "Too many fragments %d, max %d\n",
+						num_trbs, TRBS_PER_SEGMENT - 1);
+				return -ENOMEM;
+			}
+
+			nop_cmd = cpu_to_le32(TRB_TYPE(TRB_TR_NOOP) |
+					ep_ring->cycle_state);
+			ep_ring->num_trbs_free -= usable;
+			do {
+				trb->generic.field[0] = 0;
+				trb->generic.field[1] = 0;
+				trb->generic.field[2] = 0;
+				trb->generic.field[3] = nop_cmd;
+				trb++;
+			} while (--usable);
+			ep_ring->enqueue = trb;
+			if (room_on_ring(xhci, ep_ring, num_trbs))
+				break;
+		}
 
 		if (ep_ring == xhci->cmd_ring) {
 			xhci_err(xhci, "Do not support expand command ring\n");