From 8c6ebb3a7bdd1298f47e6583899fbe66c537bf7c Mon Sep 17 00:00:00 2001
From: Lu Baolu <baolu.lu@linux.intel.com>
Date: Mon, 23 Jan 2017 14:20:01 +0200
Subject: [PATCH 190/255] usb: xhci: avoid unnecessary calculation

No need to calculate remainder and length_field, if there is
no data phase of a control transfer.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit fb79a6da459b20554151eed84c991cd9bd35ff15)
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
---
 drivers/usb/host/xhci-ring.c |   20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -3240,7 +3240,7 @@ int xhci_queue_ctrl_tx(struct xhci_hcd *
 	struct usb_ctrlrequest *setup;
 	struct xhci_generic_trb *start_trb;
 	int start_cycle;
-	u32 field, length_field, remainder;
+	u32 field;
 	struct urb_priv *urb_priv;
 	struct xhci_td *td;
 
@@ -3313,16 +3313,16 @@ int xhci_queue_ctrl_tx(struct xhci_hcd *
 	else
 		field = TRB_TYPE(TRB_DATA);
 
-	remainder = xhci_td_remainder(xhci, 0,
-				   urb->transfer_buffer_length,
-				   urb->transfer_buffer_length,
-				   urb, 1);
-
-	length_field = TRB_LEN(urb->transfer_buffer_length) |
-		TRB_TD_SIZE(remainder) |
-		TRB_INTR_TARGET(0);
-
 	if (urb->transfer_buffer_length > 0) {
+		u32 length_field, remainder;
+
+		remainder = xhci_td_remainder(xhci, 0,
+				urb->transfer_buffer_length,
+				urb->transfer_buffer_length,
+				urb, 1);
+		length_field = TRB_LEN(urb->transfer_buffer_length) |
+				TRB_TD_SIZE(remainder) |
+				TRB_INTR_TARGET(0);
 		if (setup->bRequestType & USB_DIR_IN)
 			field |= TRB_DIR_IN;
 		queue_trb(xhci, ep_ring, true,