Hi,
The following diff makes the trb iteration code easier to read and
understand. I don't know why it needed to be done the other way around.
General agreement and support from stsp@.
Paul
Index: dev/usb/xhci.c
===================================================================
RCS file: /cvs/src/sys/dev/usb/xhci.c,v
retrieving revision 1.77
diff -u -p -u -p -r1.77 xhci.c
--- dev/usb/xhci.c 8 Sep 2017 10:25:19 -0000 1.77
+++ dev/usb/xhci.c 6 Nov 2017 11:58:01 -0000
@@ -2763,17 +2768,18 @@ xhci_device_isoc_start(struct usbd_xfer
paddr = DMAADDR(&xfer->dmabuf, offs);
/* Chain more TRBs if needed. */
- for (i = ntrb - 1; i > 0; i--) {
- len = xfer->frlengths[ntrb - i];
+ for (i = 1; i < ntrb; i++) {
+ int last = (i == ntrb - 1);
+ len = xfer->frlengths[i];
KASSERT(len <= UGETW(ed->wMaxPacketSize));
/* Next (or Last) TRB. */
- trb = xhci_xfer_get_trb(sc, xfer, &toggle, (i == 1));
+ trb = xhci_xfer_get_trb(sc, xfer, &toggle, last);
flags = XHCI_TRB_TYPE_NORMAL | toggle;
if (usbd_xfer_isread(xfer))
flags |= XHCI_TRB_ISP;
- flags |= (i == 1) ? XHCI_TRB_IOC : XHCI_TRB_CHAIN;
+ flags |= last ? XHCI_TRB_IOC : XHCI_TRB_CHAIN;
trb->trb_paddr = htole64(paddr);
trb->trb_status = htole32(
