diff options
authorSarah Sharp <sarah.a.sharp@linux.intel.com>2011-02-23 18:12:29 -0800
committerGreg Kroah-Hartman <gregkh@suse.de>2011-03-23 13:16:47 -0700
commitdd152cbc245edb3c3f6df1d01a8794195bdfb2de (patch)
parentc79e294f47de4595a47ae4cef68c86b872e4550c (diff)
xhci: Fix cycle bit calculation during stall handling.
commit 01a1fdb9a7afa5e3c14c9316d6f380732750b4e4 upstream. When an endpoint stalls, we need to update the xHCI host's internal dequeue pointer to move it past the stalled transfer. This includes updating the cycle bit (TRB ownership bit) if we have moved the dequeue pointer past a link TRB with the toggle cycle bit set. When we're trying to find the new dequeue segment, find_trb_seg() is supposed to keep track of whether we've passed any link TRBs with the toggle cycle bit set. However, this while loop's body while (cur_seg->trbs > trb || &cur_seg->trbs[TRBS_PER_SEGMENT - 1] < trb) { Will never get executed if the ring only contains one segment. find_trb_seg() will return immediately, without updating the new cycle bit. Since find_trb_seg() has no idea where in the segment the TD that stalled was, make the caller, xhci_find_new_dequeue_state(), check for this special case and update the cycle bit accordingly. This patch should be queued to kernels all the way back to 2.6.31. Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com> Tested-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
1 files changed, 14 insertions, 0 deletions
diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index 974d49205569..38fb6820489d 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -417,6 +417,20 @@ void xhci_find_new_dequeue_state(struct xhci_hcd *xhci,
state->new_cycle_state = ~(state->new_cycle_state) & 0x1;
next_trb(xhci, ep_ring, &state->new_deq_seg, &state->new_deq_ptr);
+ /*
+ * If there is only one segment in a ring, find_trb_seg()'s while loop
+ * will not run, and it will return before it has a chance to see if it
+ * needs to toggle the cycle bit. It can't tell if the stalled transfer
+ * ended just before the link TRB on a one-segment ring, or if the TD
+ * wrapped around the top of the ring, because it doesn't have the TD in
+ * question. Look for the one-segment case where stalled TRB's address
+ * is greater than the new dequeue pointer address.
+ */
+ if (ep_ring->first_seg == ep_ring->first_seg->next &&
+ state->new_deq_ptr < dev->eps[ep_index].stopped_trb)
+ state->new_cycle_state ^= 0x1;
+ xhci_dbg(xhci, "Cycle state = 0x%x\n", state->new_cycle_state);
/* Don't update the ring cycle state for the producer (us). */
xhci_dbg(xhci, "New dequeue segment = %p (virtual)\n",