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Revert "usb: xhci: Link TRB must not occur within a USB payload burst" 

This reverts commit 35773dac5f.  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
This commit is contained in:
Sarah Sharp 2014-01-31 11:52:57 -08:00
parent 9cf00d9170
commit 3d4b81eda2
2 changed files with 2 additions and 54 deletions
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54
drivers/usb/host/xhci-ring.c
View File

@ -2967,58 +2967,8 @@ static int prepare_ring(struct xhci_hcd *xhci, struct xhci_ring *ep_ring,
}
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");

2
include/linux/usb.h
View File

@ -1265,8 +1265,6 @@ typedef void (*usb_complete_t)(struct urb *);
* @sg: scatter gather buffer list, the buffer size of each element in
* the list (except the last) must be divisible by the endpoint's
* max packet size if no_sg_constraint isn't set in 'struct usb_bus'
* (FIXME: scatter-gather under xHCI is broken for periodic transfers.
* Do not use urb->sg for interrupt endpoints for now, only bulk.)
* @num_mapped_sgs: (internal) number of mapped sg entries
* @num_sgs: number of entries in the sg list
* @transfer_buffer_length: How big is transfer_buffer. The transfer may