[src/trunk]: src/sys/dev/usb Fix "spurious event" when command ring rolls over.

[skrll <skrll%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/1461907b84be
branches:  trunk
changeset: 347572:1461907b84be
user:      skrll <skrll%NetBSD.org@localhost>
date:      Sat Sep 03 12:07:41 2016 +0000

description:
Fix "spurious event" when command ring rolls over.
When the enqueue pointer of command ring points at the last TRB,
address of Link TRB was stored in sc_command_addr.
It should be address of 0th TRB of ring.

>From t-hash

diffstat:

 sys/dev/usb/xhci.c |  13 ++++++++++---
 1 files changed, 10 insertions(+), 3 deletions(-)

diffs (34 lines):

diff -r eb7548c94355 -r 1461907b84be sys/dev/usb/xhci.c
--- a/sys/dev/usb/xhci.c        Sat Sep 03 12:06:50 2016 +0000
+++ b/sys/dev/usb/xhci.c        Sat Sep 03 12:07:41 2016 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: xhci.c,v 1.66 2016/09/03 12:06:50 skrll Exp $  */
+/*     $NetBSD: xhci.c,v 1.67 2016/09/03 12:07:41 skrll Exp $  */
 
 /*
  * Copyright (c) 2013 Jonathan A. Kollasch
@@ -34,7 +34,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: xhci.c,v 1.66 2016/09/03 12:06:50 skrll Exp $");
+__KERNEL_RCSID(0, "$NetBSD: xhci.c,v 1.67 2016/09/03 12:07:41 skrll Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_usb.h"
@@ -2498,7 +2498,14 @@
 
        /* XXX KASSERT may fire when cv_timedwait unlocks sc_lock */
        KASSERT(sc->sc_command_addr == 0);
-       sc->sc_command_addr = xhci_ring_trbp(cr, cr->xr_ep);
+       /*
+        * If enqueue pointer points at last of ring, it's Link TRB,
+        * command TRB will be stored in 0th TRB.
+        */
+       if (cr->xr_ep == cr->xr_ntrb - 1)
+               sc->sc_command_addr = xhci_ring_trbp(cr, 0);
+       else
+               sc->sc_command_addr = xhci_ring_trbp(cr, cr->xr_ep);
 
        mutex_enter(&cr->xr_lock);
        xhci_ring_put(sc, cr, NULL, trb, 1);