xhci: Fix isoc TD encoding.

commit 760973d2a74b93eb1697981f7448f0e62767cfc4 upstream.

An isochronous TD is comprised of one isochronous TRB chained to zero or
more normal TRBs.  Only the isoc TRB has the TBC and TLBPC fields.  The
normal TRBs must set those fields to zeroes.  The code was setting the
TBC and TLBPC fields for both isoc and normal TRBs.  Fix this.

This should be backported to stable kernels as old as 3.0, that contain
the commit b61d378f2da41c748aba6ca19d77e1e1c02bcea5 " xhci 1.0: Set
transfer burst last packet count field."

Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index 2ed591d..3b5b81c 100644 (file)
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -3617,9 +3617,11 @@ static int xhci_queue_isoc_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
                td = urb_priv->td[i];
                for (j = 0; j < trbs_per_td; j++) {
                        u32 remainder = 0;
-                       field = TRB_TBC(burst_count) | TRB_TLBPC(residue);
+                       field = 0;
 
                        if (first_trb) {
+                               field = TRB_TBC(burst_count) |
+                                       TRB_TLBPC(residue);
                                /* Queue the isoc TRB */
                                field |= TRB_TYPE(TRB_ISOC);
                                /* Assume URB_ISO_ASAP is set */