diff options
| -rw-r--r-- | drivers/usb/host/xhci-ring.c | 19 |
1 files changed, 18 insertions, 1 deletions
diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c index b520b37c0f3..407d33fb5e8 100644 --- a/drivers/usb/host/xhci-ring.c +++ b/drivers/usb/host/xhci-ring.c @@ -242,10 +242,27 @@ static int room_on_ring(struct xhci_hcd *xhci, struct xhci_ring *ring, int i; union xhci_trb *enq = ring->enqueue; struct xhci_segment *enq_seg = ring->enq_seg; + struct xhci_segment *cur_seg; + unsigned int left_on_ring; /* Check if ring is empty */ - if (enq == ring->dequeue) + if (enq == ring->dequeue) { + /* Can't use link trbs */ + left_on_ring = TRBS_PER_SEGMENT - 1; + for (cur_seg = enq_seg->next; cur_seg != enq_seg; + cur_seg = cur_seg->next) + left_on_ring += TRBS_PER_SEGMENT - 1; + + /* Always need one TRB free in the ring. */ + left_on_ring -= 1; + if (num_trbs > left_on_ring) { + xhci_warn(xhci, "Not enough room on ring; " + "need %u TRBs, %u TRBs left\n", + num_trbs, left_on_ring); + return 0; + } return 1; + } /* Make sure there's an extra empty TRB available */ for (i = 0; i <= num_trbs; ++i) { if (enq == ring->dequeue) |