Module Name: src
Committed By: dsl
Date: Tue Dec 10 19:39:42 UTC 2013
Modified Files:
src/sys/dev/usb: xhci.c
Log Message:
Add a few comments about some perversities of the xhci specification.
XXX: I can't see any code that ensures there is space in the rings.
XXX: Nothing stops buffer fragments crossing 64kB boundaries.
To generate a diff of this commit:
cvs rdiff -u -r1.10 -r1.11 src/sys/dev/usb/xhci.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/dev/usb/xhci.c
diff -u src/sys/dev/usb/xhci.c:1.10 src/sys/dev/usb/xhci.c:1.11
--- src/sys/dev/usb/xhci.c:1.10 Sun Nov 17 16:11:35 2013
+++ src/sys/dev/usb/xhci.c Tue Dec 10 19:39:42 2013
@@ -1,4 +1,4 @@
-/* $NetBSD: xhci.c,v 1.10 2013/11/17 16:11:35 skrll Exp $ */
+/* $NetBSD: xhci.c,v 1.11 2013/12/10 19:39:42 dsl Exp $ */
/*
* Copyright (c) 2013 Jonathan A. Kollasch
@@ -27,7 +27,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: xhci.c,v 1.10 2013/11/17 16:11:35 skrll Exp $");
+__KERNEL_RCSID(0, "$NetBSD: xhci.c,v 1.11 2013/12/10 19:39:42 dsl Exp $");
#include <sys/param.h>
#include <sys/systm.h>
@@ -1621,6 +1621,15 @@ xhci_ring_put(struct xhci_softc * const
ri = xr->xr_ep;
cs = xr->xr_cs;
+ /*
+ * Although the xhci hardware can do scatter/gather dma from
+ * arbitrary sized buffers, there is a non-obvious restriction
+ * that a LINK trb is only allowed at the end of a burst of
+ * transfers - which might be 16kB.
+ * Arbitrary aligned LINK trb definitely fail on Ivy bridge.
+ * The simple solution is not to allow a LINK trb in the middle
+ * of anything - as here.
+ */
if (ri + ntrbs >= (xr->xr_ntrb - 1)) {
parameter = xhci_ring_trbp(xr, 0);
status = 0;
@@ -1639,6 +1648,7 @@ xhci_ring_put(struct xhci_softc * const
ri++;
+ /* Write any subsequent TRB first */
for (i = 1; i < ntrbs; i++) {
parameter = trbs[i].trb_0;
status = trbs[i].trb_2;
@@ -1658,6 +1668,7 @@ xhci_ring_put(struct xhci_softc * const
ri++;
}
+ /* Write the first TRB last */
i = 0;
{
parameter = trbs[i].trb_0;
@@ -2659,6 +2670,17 @@ xhci_device_bulk_start(usbd_xfer_handle
KASSERT((xfer->rqflags & URQ_REQUEST) == 0);
parameter = DMAADDR(dma, 0);
+ /*
+ * XXX: The physical buffer must not cross a 64k boundary.
+ * If the user supplied buffer crosses such a boundary then 2
+ * (or more) TRB should be used.
+ * If multiple TRB are used the td_size field must be set correctly.
+ * For v1.0 devices (like ivy bridge) this is the number of usb data
+ * blocks needed to complete the transfer.
+ * Setting it to 1 in the last TRB causes an extra zero-length
+ * data block be sent.
+ * The earlier documentation differs, I don't know how it behaves.
+ */
KASSERT(len <= 0x10000);
status = XHCI_TRB_2_IRQ_SET(0) |
XHCI_TRB_2_TDSZ_SET(1) |
