On Tue, May 11, 2010 at 4:03 AM, John Youn <John.Youn@xxxxxxxxxxxx> wrote:
> 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>
> Signed-off-by: Sarah Sharp <sarah.a.sharp@xxxxxxxxxxxxxxx>
> ---
>
> Forwarding to Greg KH
>
> drivers/usb/host/xhci-ring.c | 71 ++++++++++++++++++++++++++++++++++--------
> 1 files changed, 58 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
> index b648efa..74d0c2d 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 +199,15 @@ 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) {
> + next->link.control |= TRB_CHAIN;
> +
> + /* Give this link TRB to the hardware */
> + wmb();
> + next->link.control ^= 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 +244,13 @@ 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 */
Please see Documentation/CodingStyle for multi-line comments.
> + 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 +1711,43 @@ 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)) {
> +
> + /* If we're not dealing with 0.95 hardware,
> + * clear the chain bit.
> + */
Same here.
> + if (!xhci_link_trb_quirk(xhci))
> + next->link.control &= ~TRB_CHAIN;
> + else
> + 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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