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>

1 files changed, 21 insertions, 7 deletions

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index 59f81b560483..1ee6de92193a 100644
--- 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 {