Revert "usb: xhci: Link TRB must not occur within a USB payload burst"
This reverts commit 35773dac5f862cb1c82ea151eba3e2f6de51ec3e. It's a
hack that caused regressions in the usb-storage and userspace USB
drivers that use usbfs and libusb. Commit 70cabb7d992f "xhci 1.0: Limit
arbitrarily-aligned scatter gather." should fix the issues seen with the
ax88179_178a driver on xHCI 1.0 hosts, without causing regressions.
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: stable@vger.kernel.org # 3.12
diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index 0272450..0ed64eb 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -2967,58 +2967,8 @@
}
while (1) {
- if (room_on_ring(xhci, ep_ring, num_trbs)) {
- union xhci_trb *trb = ep_ring->enqueue;
- unsigned int usable = ep_ring->enq_seg->trbs +
- TRBS_PER_SEGMENT - 1 - trb;
- u32 nop_cmd;
-
- /*
- * Section 4.11.7.1 TD Fragments states that a link
- * TRB must only occur at the boundary between
- * data bursts (eg 512 bytes for 480M).
- * While it is possible to split a large fragment
- * we don't know the size yet.
- * Simplest solution is to fill the trb before the
- * LINK with nop commands.
- */
- if (num_trbs == 1 || num_trbs <= usable || usable == 0)
- break;
-
- if (ep_ring->type != TYPE_BULK)
- /*
- * While isoc transfers might have a buffer that
- * crosses a 64k boundary it is unlikely.
- * Since we can't add NOPs without generating
- * gaps in the traffic just hope it never
- * happens at the end of the ring.
- * This could be fixed by writing a LINK TRB
- * instead of the first NOP - however the
- * TRB_TYPE_LINK_LE32() calls would all need
- * changing to check the ring length.
- */
- break;
-
- if (num_trbs >= TRBS_PER_SEGMENT) {
- xhci_err(xhci, "Too many fragments %d, max %d\n",
- num_trbs, TRBS_PER_SEGMENT - 1);
- return -ENOMEM;
- }
-
- nop_cmd = cpu_to_le32(TRB_TYPE(TRB_TR_NOOP) |
- ep_ring->cycle_state);
- ep_ring->num_trbs_free -= usable;
- do {
- trb->generic.field[0] = 0;
- trb->generic.field[1] = 0;
- trb->generic.field[2] = 0;
- trb->generic.field[3] = nop_cmd;
- trb++;
- } while (--usable);
- ep_ring->enqueue = trb;
- if (room_on_ring(xhci, ep_ring, num_trbs))
- break;
- }
+ if (room_on_ring(xhci, ep_ring, num_trbs))
+ break;
if (ep_ring == xhci->cmd_ring) {
xhci_err(xhci, "Do not support expand command ring\n");