xhci: use boolean to indicate last trb in td remainder calculation

We only need to know if we are queuing the last trb for a TD when
calculating the td remainder field.
The total number of trbs left is not used.

We won't be able to trust the pre-calculated number of trbs used if we
need to align trb data by splitting or merging trbs in order to satisfy
comply with data alignment requirements in xhci specs section 4.11.7.1.

Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/xhci-ring.c

@@ -3092,7 +3092,7 @@ int xhci_queue_intr_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
  */
 static u32 xhci_td_remainder(struct xhci_hcd *xhci, int transferred,
 			      int trb_buff_len, unsigned int td_total_len,
-			      struct urb *urb, unsigned int num_trbs_left)
+			      struct urb *urb, bool more_trbs_coming)
 {
 	u32 maxp, total_packet_count;
 
@@ -3101,7 +3101,7 @@ static u32 xhci_td_remainder(struct xhci_hcd *xhci, int transferred,
 		return ((td_total_len - transferred) >> 10);
 
 	/* One TRB with a zero-length data packet. */
-	if (num_trbs_left == 0 || (transferred == 0 && trb_buff_len == 0) ||
+	if (!more_trbs_coming || (transferred == 0 && trb_buff_len == 0) ||
 	    trb_buff_len == td_total_len)
 		return 0;
 
@@ -3216,7 +3216,7 @@ int xhci_queue_bulk_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
 			field |= TRB_CHAIN;
 		} else {
 			field |= TRB_IOC;
-			more_trbs_coming = need_zero_pkt;
+			more_trbs_coming = false;
 			td->last_trb = ring->enqueue;
 		}
 
@@ -3227,13 +3227,12 @@ int xhci_queue_bulk_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
 		/* Set the TRB length, TD size, and interrupter fields. */
 		remainder = xhci_td_remainder(xhci, running_total,
 							trb_buff_len, full_len,
-							urb, num_trbs - i - 1);
-
+							urb, more_trbs_coming);
 		length_field = TRB_LEN(trb_buff_len) |
 			TRB_TD_SIZE(remainder) |
 			TRB_INTR_TARGET(0);
 
-		queue_trb(xhci, ring, more_trbs_coming,
+		queue_trb(xhci, ring, more_trbs_coming | need_zero_pkt,
 				lower_32_bits(addr),
 				upper_32_bits(addr),
 				length_field,
@@ -3657,7 +3656,7 @@ static int xhci_queue_isoc_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
 			/* Set the TRB length, TD size, & interrupter fields. */
 			remainder = xhci_td_remainder(xhci, running_total,
 						   trb_buff_len, td_len,
-						   urb, trbs_per_td - j - 1);
+						   urb, more_trbs_coming);
 
 			length_field = TRB_LEN(trb_buff_len) |
 				TRB_INTR_TARGET(0);