2 files changed, 27 insertions, 1 deletions

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index 27d690d889af..cc5963263a65 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -3123,6 +3123,27 @@ static int count_isoc_trbs_needed(struct xhci_hcd *xhci,
         return num_trbs;
 }
 
+/*
+ * The transfer burst count field of the isochronous TRB defines the number of
+ * bursts that are required to move all packets in this TD.  Only SuperSpeed
+ * devices can burst up to bMaxBurst number of packets per service interval.
+ * This field is zero based, meaning a value of zero in the field means one
+ * burst.  Basically, for everything but SuperSpeed devices, this field will be
+ * zero.  Only xHCI 1.0 host controllers support this field.
+ */
+static unsigned int xhci_get_burst_count(struct xhci_hcd *xhci,
+                struct usb_device *udev,
+                struct urb *urb, unsigned int total_packet_count)
+{
+        unsigned int max_burst;
+
+        if (xhci->hci_version < 0x100 || udev->speed != USB_SPEED_SUPER)
+                return 0;
+
+        max_burst = urb->ep->ss_ep_comp.bMaxBurst;
+        return roundup(total_packet_count, max_burst + 1) - 1;
+}
+
 /* This is for isoc transfer */
 static int xhci_queue_isoc_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
                 struct urb *urb, int slot_id, unsigned int ep_index)
@@ -3164,14 +3185,18 @@ static int xhci_queue_isoc_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
         /* Queue the first TRB, even if it's zero-length */
         for (i = 0; i < num_tds; i++) {
                 unsigned int total_packet_count;
+                unsigned int burst_count;
 
                 first_trb = true;
                 running_total = 0;
                 addr = start_addr + urb->iso_frame_desc[i].offset;
                 td_len = urb->iso_frame_desc[i].length;
                 td_remain_len = td_len;
+                /* FIXME: Ignoring zero-length packets, can those happen? */
                 total_packet_count = roundup(td_len,
                                 le16_to_cpu(urb->ep->desc.wMaxPacketSize));
+                burst_count = xhci_get_burst_count(xhci, urb->dev, urb,
+                                total_packet_count);
 
                 trbs_per_td = count_isoc_trbs_needed(xhci, urb, i);
 
@@ -3185,7 +3210,7 @@ static int xhci_queue_isoc_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
 
                 for (j = 0; j < trbs_per_td; j++) {
                         u32 remainder = 0;
-                        field = 0;
+                        field = TRB_TBC(burst_count);
 
                         if (first_trb) {
                                 /* Queue the isoc TRB */
diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index 85e779808189..87ec3b079728 100644
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -943,6 +943,7 @@ struct xhci_event_cmd {
 /* Interrupter Target - which MSI-X vector to target the completion event at */
 #define TRB_INTR_TARGET(p)      (((p) & 0x3ff) << 22)
 #define GET_INTR_TARGET(p)      (((p) >> 22) & 0x3ff)
+#define TRB_TBC(p)              (((p) & 0x3) << 7)
 
 /* Cycle bit - indicates TRB ownership by HC or HCD */
 #define TRB_CYCLE               (1<<0)