Force the compiler to write the cycle bit of the Link TRB last. This ensures that the hardware doesn't think it owns the Link TRB before we set the chain bit. Reported by Oliver in this thread: http://marc.info/?l=linux-usb&m=124091532410219&w=2 Reported-by: Oliver Neukum <oliver@xxxxxxxxxx> Signed-off-by: Sarah Sharp <sarah.a.sharp@xxxxxxxxxxxxxxx> --- drivers/usb/host/xhci-ring.c | 5 +++-- 1 files changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c index f692e74..d42a738 100644 --- a/drivers/usb/host/xhci-ring.c +++ b/drivers/usb/host/xhci-ring.c @@ -183,13 +183,14 @@ 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) { + next->link.control &= ~TRB_CHAIN; + next->link.control |= 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_CHAIN; - next->link.control |= chain; } /* Toggle the cycle bit after the last ring segment. */ if (last_trb_on_last_seg(xhci, ring, ring->enq_seg, next)) { -- 1.5.6.5 -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
