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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: John Youn <johnyoun@synopsys.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
John Youn 2010-05-10 15:33:00 -07:00 committed by Greg Kroah-Hartman
parent b0608690c2
commit 6c12db90f1
1 changed files with 58 additions and 13 deletions
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71
drivers/usb/host/xhci-ring.c
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@ -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)) {
@ -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;
}