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Commit 6c12db90 authored by John Youn's avatar John Youn Committed by Greg Kroah-Hartman
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USB: xhci: Transfer ring link TRB activation change. 



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: default avatarJohn Youn <johnyoun@synopsys.com>
Signed-off-by: default avatarSarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent b0608690

drivers/usb/host/xhci-ring.c

+58 −13
Original line number Diff line number Diff line
@@ -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();

				if (next->link.control & TRB_CYCLE)

					next->link.control &= (u32) ~TRB_CYCLE;

				else

					next->link.control |= (u32) TRB_CYCLE;

					next->link.control ^= TRB_CYCLE;

				} else {

					break;

				}

			}

			/* Toggle the cycle bit after the last ring segment. */

			if (last_trb_on_last_seg(xhci, ring, ring->enq_seg, next)) {
@@ -245,6 +246,13 @@ static int room_on_ring(struct xhci_hcd *xhci, struct xhci_ring *ring, 
	struct xhci_segment *cur_seg;

	unsigned int left_on_ring;



	/* 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) {

		/* Can't use link trbs */
@@ -1728,6 +1736,43 @@ 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.

			 */

			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;

}