xHCI: fix cycle bit set in giveback_first_trb()

giveback_first_trb() controls the cycle bit set of the start_trb, to ensure
that the start_trb is written last and the host controller will receive a
whole td at a time.

However, if the ring is wrapped and cycle bit is toggled to zero, then
giveback_first_trb() will be of no effect. In this case, set the cycle bit of
start_trb to 1 at the beginning and clear it in giveback_first_trb().

Signed-off-by: Andiry Xu <andiry.xu@amd.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index 59f81b5..1ee6de9 100644 (file)
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -2421,7 +2421,10 @@ static void giveback_first_trb(struct xhci_hcd *xhci, int slot_id,
         * isn't reordered.
         */
        wmb();
-       start_trb->field[3] |= start_cycle;
+       if (start_cycle)
+               start_trb->field[3] |= start_cycle;
+       else
+               start_trb->field[3] &= ~0x1;
        xhci_ring_ep_doorbell(xhci, slot_id, ep_index, stream_id);
 }
 
@@ -2551,9 +2554,11 @@ static int queue_bulk_sg_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
                u32 remainder = 0;
 
                /* Don't change the cycle bit of the first TRB until later */
-               if (first_trb)
+               if (first_trb) {
                        first_trb = false;
-               else
+                       if (start_cycle == 0)
+                               field |= 0x1;
+               } else
                        field |= ep_ring->cycle_state;
 
                /* Chain all the TRBs together; clear the chain bit in the last
@@ -2711,9 +2716,11 @@ int xhci_queue_bulk_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
                field = 0;
 
                /* Don't change the cycle bit of the first TRB until later */
-               if (first_trb)
+               if (first_trb) {
                        first_trb = false;
-               else
+                       if (start_cycle == 0)
+                               field |= 0x1;
+               } else
                        field |= ep_ring->cycle_state;
 
                /* Chain all the TRBs together; clear the chain bit in the last
@@ -2818,13 +2825,17 @@ int xhci_queue_ctrl_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
        /* Queue setup TRB - see section 6.4.1.2.1 */
        /* FIXME better way to translate setup_packet into two u32 fields? */
        setup = (struct usb_ctrlrequest *) urb->setup_packet;
+       field = 0;
+       field |= TRB_IDT | TRB_TYPE(TRB_SETUP);
+       if (start_cycle == 0)
+               field |= 0x1;
        queue_trb(xhci, ep_ring, false, true,
                        /* FIXME endianness is probably going to bite my ass here. */
                        setup->bRequestType | setup->bRequest << 8 | setup->wValue << 16,
                        setup->wIndex | setup->wLength << 16,
                        TRB_LEN(8) | TRB_INTR_TARGET(0),
                        /* Immediate data in pointer */
-                       TRB_IDT | TRB_TYPE(TRB_SETUP));
+                       field);
 
        /* If there's data, queue data TRBs */
        field = 0;
@@ -2951,7 +2962,10 @@ static int xhci_queue_isoc_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
                                field |= TRB_TYPE(TRB_ISOC);
                                /* Assume URB_ISO_ASAP is set */
                                field |= TRB_SIA;
-                               if (i > 0)
+                               if (i == 0) {
+                                       if (start_cycle == 0)
+                                               field |= 0x1;
+                               } else
                                        field |= ep_ring->cycle_state;
                                first_trb = false;
                        } else {