Change transfer ring behavior to not follow/activate link TRBs
until active TRBs are queued after it. This change affects
the behavior when a TD ends just before a link TRB.
Signed-off-by: John Youn <johnyoun@xxxxxxxxxxxx>
---
Sarah, here is the patch finally. I was able to do some testing on
NEC and our controller as well. Thanks.
drivers/usb/host/xhci-ring.c | 73 ++++++++++++++++++++++++++++++++++-------
1 files changed, 60 insertions(+), 13 deletions(-)
diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index b648efa..389fd9c 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -112,6 +112,12 @@ static inline int last_trb(struct xhci_hcd *xhci, struct xhci_ring *ring,
return (trb->link.control & TRB_TYPE_BITMASK) == TRB_TYPE(TRB_LINK);
}
+static inline int enqueue_is_link_trb(struct xhci_ring *ring)
+{
+ struct xhci_link_trb *link = &ring->enqueue->link;
+ return ((link->control & TRB_TYPE_BITMASK) == TRB_TYPE(TRB_LINK));
+}
+
/* Updates trb to point to the next TRB in the ring, and updates seg if the next
* TRB is in a new segment. This does not skip over link TRBs, and it does not
* effect the ring dequeue or enqueue pointers.
@@ -193,20 +199,25 @@ static void inc_enq(struct xhci_hcd *xhci, struct xhci_ring *ring, bool consumer
while (last_trb(xhci, ring, ring->enq_seg, next)) {
if (!consumer) {
if (ring != xhci->event_ring) {
- /* If we're not dealing with 0.95 hardware,
- * carry over the chain bit of the previous TRB
- * (which may mean the chain bit is cleared).
- */
- if (!xhci_link_trb_quirk(xhci)) {
- next->link.control &= ~TRB_CHAIN;
- next->link.control |= chain;
+ if (chain) {
+ xhci_dbg(xhci, "link_trb with chain bit set (part of prev trb td)\n");
+ /* If we're not dealing with 0.95 hardware,
+ * carry over the chain bit of the previous TRB
+ * (which may mean the chain bit is cleared).
+ */
+ if (!xhci_link_trb_quirk(xhci)) {
+ next->link.control &= ~TRB_CHAIN;
+ next->link.control |= chain;
+ }
+ /* Give this link TRB to the hardware */
+ wmb();
+ if (next->link.control & TRB_CYCLE)
+ next->link.control &= (u32) ~TRB_CYCLE;
+ else
+ next->link.control |= (u32) TRB_CYCLE;
+ } else {
+ break;
}
- /* Give this link TRB to the hardware */
- wmb();
- if (next->link.control & TRB_CYCLE)
- next->link.control &= (u32) ~TRB_CYCLE;
- else
- next->link.control |= (u32) TRB_CYCLE;
}
/* Toggle the cycle bit after the last ring segment. */
if (last_trb_on_last_seg(xhci, ring, ring->enq_seg, next)) {
@@ -243,6 +254,13 @@ static int room_on_ring(struct xhci_hcd *xhci, struct xhci_ring *ring,
union xhci_trb *enq = ring->enqueue;
struct xhci_segment *enq_seg = ring->enq_seg;
+ /* If we are currently pointing to a link TRB, advance the
+ * enqueue pointer before checking for space */
+ while (last_trb(xhci, ring, enq_seg, enq)) {
+ enq_seg = enq_seg->next;
+ enq = enq_seg->trbs;
+ }
+
/* Check if ring is empty */
if (enq == ring->dequeue)
return 1;
@@ -1703,6 +1721,35 @@ static int prepare_ring(struct xhci_hcd *xhci, struct xhci_ring *ep_ring,
xhci_err(xhci, "ERROR no room on ep ring\n");
return -ENOMEM;
}
+
+ if (enqueue_is_link_trb(ep_ring)) {
+ struct xhci_ring *ring = ep_ring;
+ union xhci_trb *next;
+ unsigned long long addr;
+
+ xhci_dbg(xhci, "prepare_ring: pointing to link trb\n");
+ next = ring->enqueue;
+
+ while (last_trb(xhci, ring, ring->enq_seg, next)) {
+ next->link.control &= ~TRB_CHAIN;
+ wmb();
+ next->link.control ^= (u32) TRB_CYCLE;
+
+ /* Toggle the cycle bit after the last ring segment. */
+ if (last_trb_on_last_seg(xhci, ring, ring->enq_seg, next)) {
+ ring->cycle_state = (ring->cycle_state ? 0 : 1);
+ if (!in_interrupt()) {
+ xhci_dbg(xhci, "queue_trb: Toggle cycle "
+ "state for ring %p = %i\n",
+ ring, (unsigned int)ring->cycle_state);
+ }
+ }
+ ring->enq_seg = ring->enq_seg->next;
+ ring->enqueue = ring->enq_seg->trbs;
+ next = ring->enqueue;
+ }
+ }
+
return 0;
}
--
1.6.6.1
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