USB: Move wusbcore and UWB to staging as it is obsolete

The UWB and wusbcore code is long obsolete, so let us just move the code
out of the real part of the kernel and into the drivers/staging/
location with plans to remove it entirely in a few releases.

Link: https://lore.kernel.org/r/20190806101509.GA11280@kroah.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 2927 insertions, 0 deletions

diff --git a/drivers/staging/wusbcore/wa-xfer.c b/drivers/staging/wusbcore/wa-xfer.c
new file mode 100644
index 000000000000..abf88cea37bb
--- /dev/null
+++ b/drivers/staging/wusbcore/wa-xfer.c
@@ -0,0 +1,2927 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * WUSB Wire Adapter
+ * Data transfer and URB enqueing
+ *
+ * Copyright (C) 2005-2006 Intel Corporation
+ * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>
+ *
+ * How transfers work: get a buffer, break it up in segments (segment
+ * size is a multiple of the maxpacket size). For each segment issue a
+ * segment request (struct wa_xfer_*), then send the data buffer if
+ * out or nothing if in (all over the DTO endpoint).
+ *
+ * For each submitted segment request, a notification will come over
+ * the NEP endpoint and a transfer result (struct xfer_result) will
+ * arrive in the DTI URB. Read it, get the xfer ID, see if there is
+ * data coming (inbound transfer), schedule a read and handle it.
+ *
+ * Sounds simple, it is a pain to implement.
+ *
+ *
+ * ENTRY POINTS
+ *
+ *   FIXME
+ *
+ * LIFE CYCLE / STATE DIAGRAM
+ *
+ *   FIXME
+ *
+ * THIS CODE IS DISGUSTING
+ *
+ *   Warned you are; it's my second try and still not happy with it.
+ *
+ * NOTES:
+ *
+ *   - No iso
+ *
+ *   - Supports DMA xfers, control, bulk and maybe interrupt
+ *
+ *   - Does not recycle unused rpipes
+ *
+ *     An rpipe is assigned to an endpoint the first time it is used,
+ *     and then it's there, assigned, until the endpoint is disabled
+ *     (destroyed [{h,d}wahc_op_ep_disable()]. The assignment of the
+ *     rpipe to the endpoint is done under the wa->rpipe_sem semaphore
+ *     (should be a mutex).
+ *
+ *     Two methods it could be done:
+ *
+ *     (a) set up a timer every time an rpipe's use count drops to 1
+ *         (which means unused) or when a transfer ends. Reset the
+ *         timer when a xfer is queued. If the timer expires, release
+ *         the rpipe [see rpipe_ep_disable()].
+ *
+ *     (b) when looking for free rpipes to attach [rpipe_get_by_ep()],
+ *         when none are found go over the list, check their endpoint
+ *         and their activity record (if no last-xfer-done-ts in the
+ *         last x seconds) take it
+ *
+ *     However, due to the fact that we have a set of limited
+ *     resources (max-segments-at-the-same-time per xfer,
+ *     xfers-per-ripe, blocks-per-rpipe, rpipes-per-host), at the end
+ *     we are going to have to rebuild all this based on an scheduler,
+ *     to where we have a list of transactions to do and based on the
+ *     availability of the different required components (blocks,
+ *     rpipes, segment slots, etc), we go scheduling them. Painful.
+ */
+#include <linux/spinlock.h>
+#include <linux/slab.h>
+#include <linux/hash.h>
+#include <linux/ratelimit.h>
+#include <linux/export.h>
+#include <linux/scatterlist.h>
+
+#include "wa-hc.h"
+#include "wusbhc.h"
+
+enum {
+	/* [WUSB] section 8.3.3 allocates 7 bits for the segment index. */
+	WA_SEGS_MAX = 128,
+};
+
+enum wa_seg_status {
+	WA_SEG_NOTREADY,
+	WA_SEG_READY,
+	WA_SEG_DELAYED,
+	WA_SEG_SUBMITTED,
+	WA_SEG_PENDING,
+	WA_SEG_DTI_PENDING,
+	WA_SEG_DONE,
+	WA_SEG_ERROR,
+	WA_SEG_ABORTED,
+};
+
+static void wa_xfer_delayed_run(struct wa_rpipe *);
+static int __wa_xfer_delayed_run(struct wa_rpipe *rpipe, int *dto_waiting);
+
+/*
+ * Life cycle governed by 'struct urb' (the refcount of the struct is
+ * that of the 'struct urb' and usb_free_urb() would free the whole
+ * struct).
+ */
+struct wa_seg {
+	struct urb tr_urb;		/* transfer request urb. */
+	struct urb *isoc_pack_desc_urb;	/* for isoc packet descriptor. */
+	struct urb *dto_urb;		/* for data output. */
+	struct list_head list_node;	/* for rpipe->req_list */
+	struct wa_xfer *xfer;		/* out xfer */
+	u8 index;			/* which segment we are */
+	int isoc_frame_count;	/* number of isoc frames in this segment. */
+	int isoc_frame_offset;	/* starting frame offset in the xfer URB. */
+	/* Isoc frame that the current transfer buffer corresponds to. */
+	int isoc_frame_index;
+	int isoc_size;	/* size of all isoc frames sent by this seg. */
+	enum wa_seg_status status;
+	ssize_t result;			/* bytes xfered or error */
+	struct wa_xfer_hdr xfer_hdr;
+};
+
+static inline void wa_seg_init(struct wa_seg *seg)
+{
+	usb_init_urb(&seg->tr_urb);
+
+	/* set the remaining memory to 0. */
+	memset(((void *)seg) + sizeof(seg->tr_urb), 0,
+		sizeof(*seg) - sizeof(seg->tr_urb));
+}
+
+/*
+ * Protected by xfer->lock
+ *
+ */
+struct wa_xfer {
+	struct kref refcnt;
+	struct list_head list_node;
+	spinlock_t lock;
+	u32 id;
+
+	struct wahc *wa;		/* Wire adapter we are plugged to */
+	struct usb_host_endpoint *ep;
+	struct urb *urb;		/* URB we are transferring for */
+	struct wa_seg **seg;		/* transfer segments */
+	u8 segs, segs_submitted, segs_done;
+	unsigned is_inbound:1;
+	unsigned is_dma:1;
+	size_t seg_size;
+	int result;
+
+	gfp_t gfp;			/* allocation mask */
+
+	struct wusb_dev *wusb_dev;	/* for activity timestamps */
+};
+
+static void __wa_populate_dto_urb_isoc(struct wa_xfer *xfer,
+	struct wa_seg *seg, int curr_iso_frame);
+static void wa_complete_remaining_xfer_segs(struct wa_xfer *xfer,
+		int starting_index, enum wa_seg_status status);
+
+static inline void wa_xfer_init(struct wa_xfer *xfer)
+{
+	kref_init(&xfer->refcnt);
+	INIT_LIST_HEAD(&xfer->list_node);
+	spin_lock_init(&xfer->lock);
+}
+
+/*
+ * Destroy a transfer structure
+ *
+ * Note that freeing xfer->seg[cnt]->tr_urb will free the containing
+ * xfer->seg[cnt] memory that was allocated by __wa_xfer_setup_segs.
+ */
+static void wa_xfer_destroy(struct kref *_xfer)
+{
+	struct wa_xfer *xfer = container_of(_xfer, struct wa_xfer, refcnt);
+	if (xfer->seg) {
+		unsigned cnt;
+		for (cnt = 0; cnt < xfer->segs; cnt++) {
+			struct wa_seg *seg = xfer->seg[cnt];
+			if (seg) {
+				usb_free_urb(seg->isoc_pack_desc_urb);
+				if (seg->dto_urb) {
+					kfree(seg->dto_urb->sg);
+					usb_free_urb(seg->dto_urb);
+				}
+				usb_free_urb(&seg->tr_urb);
+			}
+		}
+		kfree(xfer->seg);
+	}
+	kfree(xfer);
+}
+
+static void wa_xfer_get(struct wa_xfer *xfer)
+{
+	kref_get(&xfer->refcnt);
+}
+
+static void wa_xfer_put(struct wa_xfer *xfer)
+{
+	kref_put(&xfer->refcnt, wa_xfer_destroy);
+}
+
+/*
+ * Try to get exclusive access to the DTO endpoint resource.  Return true
+ * if successful.
+ */
+static inline int __wa_dto_try_get(struct wahc *wa)
+{
+	return (test_and_set_bit(0, &wa->dto_in_use) == 0);
+}
+
+/* Release the DTO endpoint resource. */
+static inline void __wa_dto_put(struct wahc *wa)
+{
+	clear_bit_unlock(0, &wa->dto_in_use);
+}
+
+/* Service RPIPEs that are waiting on the DTO resource. */
+static void wa_check_for_delayed_rpipes(struct wahc *wa)
+{
+	unsigned long flags;
+	int dto_waiting = 0;
+	struct wa_rpipe *rpipe;
+
+	spin_lock_irqsave(&wa->rpipe_lock, flags);
+	while (!list_empty(&wa->rpipe_delayed_list) && !dto_waiting) {
+		rpipe = list_first_entry(&wa->rpipe_delayed_list,
+				struct wa_rpipe, list_node);
+		__wa_xfer_delayed_run(rpipe, &dto_waiting);
+		/* remove this RPIPE from the list if it is not waiting. */
+		if (!dto_waiting) {
+			pr_debug("%s: RPIPE %d serviced and removed from delayed list.\n",
+				__func__,
+				le16_to_cpu(rpipe->descr.wRPipeIndex));
+			list_del_init(&rpipe->list_node);
+		}
+	}
+	spin_unlock_irqrestore(&wa->rpipe_lock, flags);
+}
+
+/* add this RPIPE to the end of the delayed RPIPE list. */
+static void wa_add_delayed_rpipe(struct wahc *wa, struct wa_rpipe *rpipe)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&wa->rpipe_lock, flags);
+	/* add rpipe to the list if it is not already on it. */
+	if (list_empty(&rpipe->list_node)) {
+		pr_debug("%s: adding RPIPE %d to the delayed list.\n",
+			__func__, le16_to_cpu(rpipe->descr.wRPipeIndex));
+		list_add_tail(&rpipe->list_node, &wa->rpipe_delayed_list);
+	}
+	spin_unlock_irqrestore(&wa->rpipe_lock, flags);
+}
+
+/*
+ * xfer is referenced
+ *
+ * xfer->lock has to be unlocked
+ *
+ * We take xfer->lock for setting the result; this is a barrier
+ * against drivers/usb/core/hcd.c:unlink1() being called after we call
+ * usb_hcd_giveback_urb() and wa_urb_dequeue() trying to get a
+ * reference to the transfer.
+ */
+static void wa_xfer_giveback(struct wa_xfer *xfer)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&xfer->wa->xfer_list_lock, flags);
+	list_del_init(&xfer->list_node);
+	usb_hcd_unlink_urb_from_ep(&(xfer->wa->wusb->usb_hcd), xfer->urb);
+	spin_unlock_irqrestore(&xfer->wa->xfer_list_lock, flags);
+	/* FIXME: segmentation broken -- kills DWA */
+	wusbhc_giveback_urb(xfer->wa->wusb, xfer->urb, xfer->result);
+	wa_put(xfer->wa);
+	wa_xfer_put(xfer);
+}
+
+/*
+ * xfer is referenced
+ *
+ * xfer->lock has to be unlocked
+ */
+static void wa_xfer_completion(struct wa_xfer *xfer)
+{
+	if (xfer->wusb_dev)
+		wusb_dev_put(xfer->wusb_dev);
+	rpipe_put(xfer->ep->hcpriv);
+	wa_xfer_giveback(xfer);
+}
+
+/*
+ * Initialize a transfer's ID
+ *
+ * We need to use a sequential number; if we use the pointer or the
+ * hash of the pointer, it can repeat over sequential transfers and
+ * then it will confuse the HWA....wonder why in hell they put a 32
+ * bit handle in there then.
+ */
+static void wa_xfer_id_init(struct wa_xfer *xfer)
+{
+	xfer->id = atomic_add_return(1, &xfer->wa->xfer_id_count);
+}
+
+/* Return the xfer's ID. */
+static inline u32 wa_xfer_id(struct wa_xfer *xfer)
+{
+	return xfer->id;
+}
+
+/* Return the xfer's ID in transport format (little endian). */
+static inline __le32 wa_xfer_id_le32(struct wa_xfer *xfer)
+{
+	return cpu_to_le32(xfer->id);
+}
+
+/*
+ * If transfer is done, wrap it up and return true
+ *
+ * xfer->lock has to be locked
+ */
+static unsigned __wa_xfer_is_done(struct wa_xfer *xfer)
+{
+	struct device *dev = &xfer->wa->usb_iface->dev;
+	unsigned result, cnt;
+	struct wa_seg *seg;
+	struct urb *urb = xfer->urb;
+	unsigned found_short = 0;
+
+	result = xfer->segs_done == xfer->segs_submitted;
+	if (result == 0)
+		goto out;
+	urb->actual_length = 0;
+	for (cnt = 0; cnt < xfer->segs; cnt++) {
+		seg = xfer->seg[cnt];
+		switch (seg->status) {
+		case WA_SEG_DONE:
+			if (found_short && seg->result > 0) {
+				dev_dbg(dev, "xfer %p ID %08X#%u: bad short segments (%zu)\n",
+					xfer, wa_xfer_id(xfer), cnt,
+					seg->result);
+				urb->status = -EINVAL;
+				goto out;
+			}
+			urb->actual_length += seg->result;
+			if (!(usb_pipeisoc(xfer->urb->pipe))
+				&& seg->result < xfer->seg_size
+			    && cnt != xfer->segs-1)
+				found_short = 1;
+			dev_dbg(dev, "xfer %p ID %08X#%u: DONE short %d "
+				"result %zu urb->actual_length %d\n",
+				xfer, wa_xfer_id(xfer), seg->index, found_short,
+				seg->result, urb->actual_length);
+			break;
+		case WA_SEG_ERROR:
+			xfer->result = seg->result;
+			dev_dbg(dev, "xfer %p ID %08X#%u: ERROR result %zi(0x%08zX)\n",
+				xfer, wa_xfer_id(xfer), seg->index, seg->result,
+				seg->result);
+			goto out;
+		case WA_SEG_ABORTED:
+			xfer->result = seg->result;
+			dev_dbg(dev, "xfer %p ID %08X#%u: ABORTED result %zi(0x%08zX)\n",
+				xfer, wa_xfer_id(xfer), seg->index, seg->result,
+				seg->result);
+			goto out;
+		default:
+			dev_warn(dev, "xfer %p ID %08X#%u: is_done bad state %d\n",
+				 xfer, wa_xfer_id(xfer), cnt, seg->status);
+			xfer->result = -EINVAL;
+			goto out;
+		}
+	}
+	xfer->result = 0;
+out:
+	return result;
+}
+
+/*
+ * Mark the given segment as done.  Return true if this completes the xfer.
+ * This should only be called for segs that have been submitted to an RPIPE.
+ * Delayed segs are not marked as submitted so they do not need to be marked
+ * as done when cleaning up.
+ *
+ * xfer->lock has to be locked
+ */
+static unsigned __wa_xfer_mark_seg_as_done(struct wa_xfer *xfer,
+	struct wa_seg *seg, enum wa_seg_status status)
+{
+	seg->status = status;
+	xfer->segs_done++;
+
+	/* check for done. */
+	return __wa_xfer_is_done(xfer);
+}
+
+/*
+ * Search for a transfer list ID on the HCD's URB list
+ *
+ * For 32 bit architectures, we use the pointer itself; for 64 bits, a
+ * 32-bit hash of the pointer.
+ *
+ * @returns NULL if not found.
+ */
+static struct wa_xfer *wa_xfer_get_by_id(struct wahc *wa, u32 id)
+{
+	unsigned long flags;
+	struct wa_xfer *xfer_itr;
+	spin_lock_irqsave(&wa->xfer_list_lock, flags);
+	list_for_each_entry(xfer_itr, &wa->xfer_list, list_node) {
+		if (id == xfer_itr->id) {
+			wa_xfer_get(xfer_itr);
+			goto out;
+		}
+	}
+	xfer_itr = NULL;
+out:
+	spin_unlock_irqrestore(&wa->xfer_list_lock, flags);
+	return xfer_itr;
+}
+
+struct wa_xfer_abort_buffer {
+	struct urb urb;
+	struct wahc *wa;
+	struct wa_xfer_abort cmd;
+};
+
+static void __wa_xfer_abort_cb(struct urb *urb)
+{
+	struct wa_xfer_abort_buffer *b = urb->context;
+	struct wahc *wa = b->wa;
+
+	/*
+	 * If the abort request URB failed, then the HWA did not get the abort
+	 * command.  Forcibly clean up the xfer without waiting for a Transfer
+	 * Result from the HWA.
+	 */
+	if (urb->status < 0) {
+		struct wa_xfer *xfer;
+		struct device *dev = &wa->usb_iface->dev;
+
+		xfer = wa_xfer_get_by_id(wa, le32_to_cpu(b->cmd.dwTransferID));
+		dev_err(dev, "%s: Transfer Abort request failed. result: %d\n",
+			__func__, urb->status);
+		if (xfer) {
+			unsigned long flags;
+			int done, seg_index = 0;
+			struct wa_rpipe *rpipe = xfer->ep->hcpriv;
+
+			dev_err(dev, "%s: cleaning up xfer %p ID 0x%08X.\n",
+				__func__, xfer, wa_xfer_id(xfer));
+			spin_lock_irqsave(&xfer->lock, flags);
+			/* skip done segs. */
+			while (seg_index < xfer->segs) {
+				struct wa_seg *seg = xfer->seg[seg_index];
+
+				if ((seg->status == WA_SEG_DONE) ||
+					(seg->status == WA_SEG_ERROR)) {
+					++seg_index;
+				} else {
+					break;
+				}
+			}
+			/* mark remaining segs as aborted. */
+			wa_complete_remaining_xfer_segs(xfer, seg_index,
+				WA_SEG_ABORTED);
+			done = __wa_xfer_is_done(xfer);
+			spin_unlock_irqrestore(&xfer->lock, flags);
+			if (done)
+				wa_xfer_completion(xfer);
+			wa_xfer_delayed_run(rpipe);
+			wa_xfer_put(xfer);
+		} else {
+			dev_err(dev, "%s: xfer ID 0x%08X already gone.\n",
+				 __func__, le32_to_cpu(b->cmd.dwTransferID));
+		}
+	}
+
+	wa_put(wa);	/* taken in __wa_xfer_abort */
+	usb_put_urb(&b->urb);
+}
+
+/*
+ * Aborts an ongoing transaction
+ *
+ * Assumes the transfer is referenced and locked and in a submitted
+ * state (mainly that there is an endpoint/rpipe assigned).
+ *
+ * The callback (see above) does nothing but freeing up the data by
+ * putting the URB. Because the URB is allocated at the head of the
+ * struct, the whole space we allocated is kfreed. *
+ */
+static int __wa_xfer_abort(struct wa_xfer *xfer)
+{
+	int result = -ENOMEM;
+	struct device *dev = &xfer->wa->usb_iface->dev;
+	struct wa_xfer_abort_buffer *b;
+	struct wa_rpipe *rpipe = xfer->ep->hcpriv;
+
+	b = kmalloc(sizeof(*b), GFP_ATOMIC);
+	if (b == NULL)
+		goto error_kmalloc;
+	b->cmd.bLength =  sizeof(b->cmd);
+	b->cmd.bRequestType = WA_XFER_ABORT;
+	b->cmd.wRPipe = rpipe->descr.wRPipeIndex;
+	b->cmd.dwTransferID = wa_xfer_id_le32(xfer);
+	b->wa = wa_get(xfer->wa);
+
+	usb_init_urb(&b->urb);
+	usb_fill_bulk_urb(&b->urb, xfer->wa->usb_dev,
+		usb_sndbulkpipe(xfer->wa->usb_dev,
+				xfer->wa->dto_epd->bEndpointAddress),
+		&b->cmd, sizeof(b->cmd), __wa_xfer_abort_cb, b);
+	result = usb_submit_urb(&b->urb, GFP_ATOMIC);
+	if (result < 0)
+		goto error_submit;
+	return result;				/* callback frees! */
+
+
+error_submit:
+	wa_put(xfer->wa);
+	if (printk_ratelimit())
+		dev_err(dev, "xfer %p: Can't submit abort request: %d\n",
+			xfer, result);
+	kfree(b);
+error_kmalloc:
+	return result;
+
+}
+
+/*
+ * Calculate the number of isoc frames starting from isoc_frame_offset
+ * that will fit a in transfer segment.
+ */
+static int __wa_seg_calculate_isoc_frame_count(struct wa_xfer *xfer,
+	int isoc_frame_offset, int *total_size)
+{
+	int segment_size = 0, frame_count = 0;
+	int index = isoc_frame_offset;
+	struct usb_iso_packet_descriptor *iso_frame_desc =
+		xfer->urb->iso_frame_desc;
+
+	while ((index < xfer->urb->number_of_packets)
+		&& ((segment_size + iso_frame_desc[index].length)
+				<= xfer->seg_size)) {
+		/*
+		 * For Alereon HWA devices, only include an isoc frame in an
+		 * out segment if it is physically contiguous with the previous
+		 * frame.  This is required because those devices expect
+		 * the isoc frames to be sent as a single USB transaction as
+		 * opposed to one transaction per frame with standard HWA.
+		 */
+		if ((xfer->wa->quirks & WUSB_QUIRK_ALEREON_HWA_CONCAT_ISOC)
+			&& (xfer->is_inbound == 0)
+			&& (index > isoc_frame_offset)
+			&& ((iso_frame_desc[index - 1].offset +
+				iso_frame_desc[index - 1].length) !=
+				iso_frame_desc[index].offset))
+			break;
+
+		/* this frame fits. count it. */
+		++frame_count;
+		segment_size += iso_frame_desc[index].length;
+
+		/* move to the next isoc frame. */
+		++index;
+	}
+
+	*total_size = segment_size;
+	return frame_count;
+}
+
+/*
+ *
+ * @returns < 0 on error, transfer segment request size if ok
+ */
+static ssize_t __wa_xfer_setup_sizes(struct wa_xfer *xfer,
+				     enum wa_xfer_type *pxfer_type)
+{
+	ssize_t result;
+	struct device *dev = &xfer->wa->usb_iface->dev;
+	size_t maxpktsize;
+	struct urb *urb = xfer->urb;
+	struct wa_rpipe *rpipe = xfer->ep->hcpriv;
+
+	switch (rpipe->descr.bmAttribute & 0x3) {
+	case USB_ENDPOINT_XFER_CONTROL:
+		*pxfer_type = WA_XFER_TYPE_CTL;
+		result = sizeof(struct wa_xfer_ctl);
+		break;
+	case USB_ENDPOINT_XFER_INT:
+	case USB_ENDPOINT_XFER_BULK:
+		*pxfer_type = WA_XFER_TYPE_BI;
+		result = sizeof(struct wa_xfer_bi);
+		break;
+	case USB_ENDPOINT_XFER_ISOC:
+		*pxfer_type = WA_XFER_TYPE_ISO;
+		result = sizeof(struct wa_xfer_hwaiso);
+		break;
+	default:
+		/* never happens */
+		BUG();
+		result = -EINVAL;	/* shut gcc up */
+	}
+	xfer->is_inbound = urb->pipe & USB_DIR_IN ? 1 : 0;
+	xfer->is_dma = urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP ? 1 : 0;
+
+	maxpktsize = le16_to_cpu(rpipe->descr.wMaxPacketSize);
+	xfer->seg_size = le16_to_cpu(rpipe->descr.wBlocks)
+		* 1 << (xfer->wa->wa_descr->bRPipeBlockSize - 1);
+	/* Compute the segment size and make sure it is a multiple of
+	 * the maxpktsize (WUSB1.0[8.3.3.1])...not really too much of
+	 * a check (FIXME) */
+	if (xfer->seg_size < maxpktsize) {
+		dev_err(dev,
+			"HW BUG? seg_size %zu smaller than maxpktsize %zu\n",
+			xfer->seg_size, maxpktsize);
+		result = -EINVAL;
+		goto error;
+	}
+	xfer->seg_size = (xfer->seg_size / maxpktsize) * maxpktsize;
+	if ((rpipe->descr.bmAttribute & 0x3) == USB_ENDPOINT_XFER_ISOC) {
+		int index = 0;
+
+		xfer->segs = 0;
+		/*
+		 * loop over urb->number_of_packets to determine how many
+		 * xfer segments will be needed to send the isoc frames.
+		 */
+		while (index < urb->number_of_packets) {
+			int seg_size; /* don't care. */
+			index += __wa_seg_calculate_isoc_frame_count(xfer,
+					index, &seg_size);
+			++xfer->segs;
+		}
+	} else {
+		xfer->segs = DIV_ROUND_UP(urb->transfer_buffer_length,
+						xfer->seg_size);
+		if (xfer->segs == 0 && *pxfer_type == WA_XFER_TYPE_CTL)
+			xfer->segs = 1;
+	}
+
+	if (xfer->segs > WA_SEGS_MAX) {
+		dev_err(dev, "BUG? oops, number of segments %zu bigger than %d\n",
+			(urb->transfer_buffer_length/xfer->seg_size),
+			WA_SEGS_MAX);
+		result = -EINVAL;
+		goto error;
+	}
+error:
+	return result;
+}
+
+static void __wa_setup_isoc_packet_descr(
+		struct wa_xfer_packet_info_hwaiso *packet_desc,
+		struct wa_xfer *xfer,
+		struct wa_seg *seg) {
+	struct usb_iso_packet_descriptor *iso_frame_desc =
+		xfer->urb->iso_frame_desc;
+	int frame_index;
+
+	/* populate isoc packet descriptor. */
+	packet_desc->bPacketType = WA_XFER_ISO_PACKET_INFO;
+	packet_desc->wLength = cpu_to_le16(struct_size(packet_desc,
+					   PacketLength,
+					   seg->isoc_frame_count));
+	for (frame_index = 0; frame_index < seg->isoc_frame_count;
+		++frame_index) {
+		int offset_index = frame_index + seg->isoc_frame_offset;
+		packet_desc->PacketLength[frame_index] =
+			cpu_to_le16(iso_frame_desc[offset_index].length);
+	}
+}
+
+
+/* Fill in the common request header and xfer-type specific data. */
+static void __wa_xfer_setup_hdr0(struct wa_xfer *xfer,
+				 struct wa_xfer_hdr *xfer_hdr0,
+				 enum wa_xfer_type xfer_type,
+				 size_t xfer_hdr_size)
+{
+	struct wa_rpipe *rpipe = xfer->ep->hcpriv;
+	struct wa_seg *seg = xfer->seg[0];
+
+	xfer_hdr0 = &seg->xfer_hdr;
+	xfer_hdr0->bLength = xfer_hdr_size;
+	xfer_hdr0->bRequestType = xfer_type;
+	xfer_hdr0->wRPipe = rpipe->descr.wRPipeIndex;
+	xfer_hdr0->dwTransferID = wa_xfer_id_le32(xfer);
+	xfer_hdr0->bTransferSegment = 0;
+	switch (xfer_type) {
+	case WA_XFER_TYPE_CTL: {
+		struct wa_xfer_ctl *xfer_ctl =
+			container_of(xfer_hdr0, struct wa_xfer_ctl, hdr);
+		xfer_ctl->bmAttribute = xfer->is_inbound ? 1 : 0;
+		memcpy(&xfer_ctl->baSetupData, xfer->urb->setup_packet,
+		       sizeof(xfer_ctl->baSetupData));
+		break;
+	}
+	case WA_XFER_TYPE_BI:
+		break;
+	case WA_XFER_TYPE_ISO: {
+		struct wa_xfer_hwaiso *xfer_iso =
+			container_of(xfer_hdr0, struct wa_xfer_hwaiso, hdr);
+		struct wa_xfer_packet_info_hwaiso *packet_desc =
+			((void *)xfer_iso) + xfer_hdr_size;
+
+		/* populate the isoc section of the transfer request. */
+		xfer_iso->dwNumOfPackets = cpu_to_le32(seg->isoc_frame_count);
+		/* populate isoc packet descriptor. */
+		__wa_setup_isoc_packet_descr(packet_desc, xfer, seg);
+		break;
+	}
+	default:
+		BUG();
+	};
+}
+
+/*
+ * Callback for the OUT data phase of the segment request
+ *
+ * Check wa_seg_tr_cb(); most comments also apply here because this
+ * function does almost the same thing and they work closely
+ * together.
+ *
+ * If the seg request has failed but this DTO phase has succeeded,
+ * wa_seg_tr_cb() has already failed the segment and moved the
+ * status to WA_SEG_ERROR, so this will go through 'case 0' and
+ * effectively do nothing.
+ */
+static void wa_seg_dto_cb(struct urb *urb)
+{
+	struct wa_seg *seg = urb->context;
+	struct wa_xfer *xfer = seg->xfer;
+	struct wahc *wa;
+	struct device *dev;
+	struct wa_rpipe *rpipe;
+	unsigned long flags;
+	unsigned rpipe_ready = 0;
+	int data_send_done = 1, release_dto = 0, holding_dto = 0;
+	u8 done = 0;
+	int result;
+
+	/* free the sg if it was used. */
+	kfree(urb->sg);
+	urb->sg = NULL;
+
+	spin_lock_irqsave(&xfer->lock, flags);
+	wa = xfer->wa;
+	dev = &wa->usb_iface->dev;
+	if (usb_pipeisoc(xfer->urb->pipe)) {
+		/* Alereon HWA sends all isoc frames in a single transfer. */
+		if (wa->quirks & WUSB_QUIRK_ALEREON_HWA_CONCAT_ISOC)
+			seg->isoc_frame_index += seg->isoc_frame_count;
+		else
+			seg->isoc_frame_index += 1;
+		if (seg->isoc_frame_index < seg->isoc_frame_count) {
+			data_send_done = 0;
+			holding_dto = 1; /* checked in error cases. */
+			/*
+			 * if this is the last isoc frame of the segment, we
+			 * can release DTO after sending this frame.
+			 */
+			if ((seg->isoc_frame_index + 1) >=
+				seg->isoc_frame_count)
+				release_dto = 1;
+		}
+		dev_dbg(dev, "xfer 0x%08X#%u: isoc frame = %d, holding_dto = %d, release_dto = %d.\n",
+			wa_xfer_id(xfer), seg->index, seg->isoc_frame_index,
+			holding_dto, release_dto);
+	}
+	spin_unlock_irqrestore(&xfer->lock, flags);
+
+	switch (urb->status) {
+	case 0:
+		spin_lock_irqsave(&xfer->lock, flags);
+		seg->result += urb->actual_length;
+		if (data_send_done) {
+			dev_dbg(dev, "xfer 0x%08X#%u: data out done (%zu bytes)\n",
+				wa_xfer_id(xfer), seg->index, seg->result);
+			if (seg->status < WA_SEG_PENDING)
+				seg->status = WA_SEG_PENDING;
+		} else {
+			/* should only hit this for isoc xfers. */
+			/*
+			 * Populate the dto URB with the next isoc frame buffer,
+			 * send the URB and release DTO if we no longer need it.
+			 */
+			 __wa_populate_dto_urb_isoc(xfer, seg,
+				seg->isoc_frame_offset + seg->isoc_frame_index);
+
+			/* resubmit the URB with the next isoc frame. */
+			/* take a ref on resubmit. */
+			wa_xfer_get(xfer);
+			result = usb_submit_urb(seg->dto_urb, GFP_ATOMIC);
+			if (result < 0) {
+				dev_err(dev, "xfer 0x%08X#%u: DTO submit failed: %d\n",
+				       wa_xfer_id(xfer), seg->index, result);
+				spin_unlock_irqrestore(&xfer->lock, flags);
+				goto error_dto_submit;
+			}
+		}
+		spin_unlock_irqrestore(&xfer->lock, flags);
+		if (release_dto) {
+			__wa_dto_put(wa);
+			wa_check_for_delayed_rpipes(wa);
+		}
+		break;
+	case -ECONNRESET:	/* URB unlinked; no need to do anything */
+	case -ENOENT:		/* as it was done by the who unlinked us */
+		if (holding_dto) {
+			__wa_dto_put(wa);
+			wa_check_for_delayed_rpipes(wa);
+		}
+		break;
+	default:		/* Other errors ... */
+		dev_err(dev, "xfer 0x%08X#%u: data out error %d\n",
+			wa_xfer_id(xfer), seg->index, urb->status);
+		goto error_default;
+	}
+
+	/* taken when this URB was submitted. */
+	wa_xfer_put(xfer);
+	return;
+
+error_dto_submit:
+	/* taken on resubmit attempt. */
+	wa_xfer_put(xfer);
+error_default:
+	spin_lock_irqsave(&xfer->lock, flags);
+	rpipe = xfer->ep->hcpriv;
+	if (edc_inc(&wa->nep_edc, EDC_MAX_ERRORS,
+		    EDC_ERROR_TIMEFRAME)){
+		dev_err(dev, "DTO: URB max acceptable errors exceeded, resetting device\n");
+		wa_reset_all(wa);
+	}
+	if (seg->status != WA_SEG_ERROR) {
+		seg->result = urb->status;
+		__wa_xfer_abort(xfer);
+		rpipe_ready = rpipe_avail_inc(rpipe);
+		done = __wa_xfer_mark_seg_as_done(xfer, seg, WA_SEG_ERROR);
+	}
+	spin_unlock_irqrestore(&xfer->lock, flags);
+	if (holding_dto) {
+		__wa_dto_put(wa);
+		wa_check_for_delayed_rpipes(wa);
+	}
+	if (done)
+		wa_xfer_completion(xfer);
+	if (rpipe_ready)
+		wa_xfer_delayed_run(rpipe);
+	/* taken when this URB was submitted. */
+	wa_xfer_put(xfer);
+}
+
+/*
+ * Callback for the isoc packet descriptor phase of the segment request
+ *
+ * Check wa_seg_tr_cb(); most comments also apply here because this
+ * function does almost the same thing and they work closely
+ * together.
+ *
+ * If the seg request has failed but this phase has succeeded,
+ * wa_seg_tr_cb() has already failed the segment and moved the
+ * status to WA_SEG_ERROR, so this will go through 'case 0' and
+ * effectively do nothing.
+ */
+static void wa_seg_iso_pack_desc_cb(struct urb *urb)
+{
+	struct wa_seg *seg = urb->context;
+	struct wa_xfer *xfer = seg->xfer;
+	struct wahc *wa;
+	struct device *dev;
+	struct wa_rpipe *rpipe;
+	unsigned long flags;
+	unsigned rpipe_ready = 0;
+	u8 done = 0;
+
+	switch (urb->status) {
+	case 0:
+		spin_lock_irqsave(&xfer->lock, flags);
+		wa = xfer->wa;
+		dev = &wa->usb_iface->dev;
+		dev_dbg(dev, "iso xfer %08X#%u: packet descriptor done\n",
+			wa_xfer_id(xfer), seg->index);
+		if (xfer->is_inbound && seg->status < WA_SEG_PENDING)
+			seg->status = WA_SEG_PENDING;
+		spin_unlock_irqrestore(&xfer->lock, flags);
+		break;
+	case -ECONNRESET:	/* URB unlinked; no need to do anything */
+	case -ENOENT:		/* as it was done by the who unlinked us */
+		break;
+	default:		/* Other errors ... */
+		spin_lock_irqsave(&xfer->lock, flags);
+		wa = xfer->wa;
+		dev = &wa->usb_iface->dev;
+		rpipe = xfer->ep->hcpriv;
+		pr_err_ratelimited("iso xfer %08X#%u: packet descriptor error %d\n",
+				wa_xfer_id(xfer), seg->index, urb->status);
+		if (edc_inc(&wa->nep_edc, EDC_MAX_ERRORS,
+			    EDC_ERROR_TIMEFRAME)){
+			dev_err(dev, "iso xfer: URB max acceptable errors exceeded, resetting device\n");
+			wa_reset_all(wa);
+		}
+		if (seg->status != WA_SEG_ERROR) {
+			usb_unlink_urb(seg->dto_urb);
+			seg->result = urb->status;
+			__wa_xfer_abort(xfer);
+			rpipe_ready = rpipe_avail_inc(rpipe);
+			done = __wa_xfer_mark_seg_as_done(xfer, seg,
+					WA_SEG_ERROR);
+		}
+		spin_unlock_irqrestore(&xfer->lock, flags);
+		if (done)
+			wa_xfer_completion(xfer);
+		if (rpipe_ready)
+			wa_xfer_delayed_run(rpipe);
+	}
+	/* taken when this URB was submitted. */
+	wa_xfer_put(xfer);
+}
+
+/*
+ * Callback for the segment request
+ *
+ * If successful transition state (unless already transitioned or
+ * outbound transfer); otherwise, take a note of the error, mark this
+ * segment done and try completion.
+ *
+ * Note we don't access until we are sure that the transfer hasn't
+ * been cancelled (ECONNRESET, ENOENT), which could mean that
+ * seg->xfer could be already gone.
+ *
+ * We have to check before setting the status to WA_SEG_PENDING
+ * because sometimes the xfer result callback arrives before this
+ * callback (geeeeeeze), so it might happen that we are already in
+ * another state. As well, we don't set it if the transfer is not inbound,
+ * as in that case, wa_seg_dto_cb will do it when the OUT data phase
+ * finishes.
+ */
+static void wa_seg_tr_cb(struct urb *urb)
+{
+	struct wa_seg *seg = urb->context;
+	struct wa_xfer *xfer = seg->xfer;
+	struct wahc *wa;
+	struct device *dev;
+	struct wa_rpipe *rpipe;
+	unsigned long flags;
+	unsigned rpipe_ready;
+	u8 done = 0;
+
+	switch (urb->status) {
+	case 0:
+		spin_lock_irqsave(&xfer->lock, flags);
+		wa = xfer->wa;
+		dev = &wa->usb_iface->dev;
+		dev_dbg(dev, "xfer %p ID 0x%08X#%u: request done\n",
+			xfer, wa_xfer_id(xfer), seg->index);
+		if (xfer->is_inbound &&
+			seg->status < WA_SEG_PENDING &&
+			!(usb_pipeisoc(xfer->urb->pipe)))
+			seg->status = WA_SEG_PENDING;
+		spin_unlock_irqrestore(&xfer->lock, flags);
+		break;
+	case -ECONNRESET:	/* URB unlinked; no need to do anything */
+	case -ENOENT:		/* as it was done by the who unlinked us */
+		break;
+	default:		/* Other errors ... */
+		spin_lock_irqsave(&xfer->lock, flags);
+		wa = xfer->wa;
+		dev = &wa->usb_iface->dev;
+		rpipe = xfer->ep->hcpriv;
+		if (printk_ratelimit())
+			dev_err(dev, "xfer %p ID 0x%08X#%u: request error %d\n",
+				xfer, wa_xfer_id(xfer), seg->index,
+				urb->status);
+		if (edc_inc(&wa->nep_edc, EDC_MAX_ERRORS,
+			    EDC_ERROR_TIMEFRAME)){
+			dev_err(dev, "DTO: URB max acceptable errors "
+				"exceeded, resetting device\n");
+			wa_reset_all(wa);
+		}
+		usb_unlink_urb(seg->isoc_pack_desc_urb);
+		usb_unlink_urb(seg->dto_urb);
+		seg->result = urb->status;
+		__wa_xfer_abort(xfer);
+		rpipe_ready = rpipe_avail_inc(rpipe);
+		done = __wa_xfer_mark_seg_as_done(xfer, seg, WA_SEG_ERROR);
+		spin_unlock_irqrestore(&xfer->lock, flags);
+		if (done)
+			wa_xfer_completion(xfer);
+		if (rpipe_ready)
+			wa_xfer_delayed_run(rpipe);
+	}
+	/* taken when this URB was submitted. */
+	wa_xfer_put(xfer);
+}
+
+/*
+ * Allocate an SG list to store bytes_to_transfer bytes and copy the
+ * subset of the in_sg that matches the buffer subset
+ * we are about to transfer.
+ */
+static struct scatterlist *wa_xfer_create_subset_sg(struct scatterlist *in_sg,
+	const unsigned int bytes_transferred,
+	const unsigned int bytes_to_transfer, int *out_num_sgs)
+{
+	struct scatterlist *out_sg;
+	unsigned int bytes_processed = 0, offset_into_current_page_data = 0,
+		nents;
+	struct scatterlist *current_xfer_sg = in_sg;
+	struct scatterlist *current_seg_sg, *last_seg_sg;
+
+	/* skip previously transferred pages. */
+	while ((current_xfer_sg) &&
+			(bytes_processed < bytes_transferred)) {
+		bytes_processed += current_xfer_sg->length;
+
+		/* advance the sg if current segment starts on or past the
+			next page. */
+		if (bytes_processed <= bytes_transferred)
+			current_xfer_sg = sg_next(current_xfer_sg);
+	}
+
+	/* the data for the current segment starts in current_xfer_sg.
+		calculate the offset. */
+	if (bytes_processed > bytes_transferred) {
+		offset_into_current_page_data = current_xfer_sg->length -
+			(bytes_processed - bytes_transferred);
+	}
+
+	/* calculate the number of pages needed by this segment. */
+	nents = DIV_ROUND_UP((bytes_to_transfer +
+		offset_into_current_page_data +
+		current_xfer_sg->offset),
+		PAGE_SIZE);
+
+	out_sg = kmalloc((sizeof(struct scatterlist) * nents), GFP_ATOMIC);
+	if (out_sg) {
+		sg_init_table(out_sg, nents);
+
+		/* copy the portion of the incoming SG that correlates to the
+		 * data to be transferred by this segment to the segment SG. */
+		last_seg_sg = current_seg_sg = out_sg;
+		bytes_processed = 0;
+
+		/* reset nents and calculate the actual number of sg entries
+			needed. */
+		nents = 0;
+		while ((bytes_processed < bytes_to_transfer) &&
+				current_seg_sg && current_xfer_sg) {
+			unsigned int page_len = min((current_xfer_sg->length -
+				offset_into_current_page_data),
+				(bytes_to_transfer - bytes_processed));
+
+			sg_set_page(current_seg_sg, sg_page(current_xfer_sg),
+				page_len,
+				current_xfer_sg->offset +
+				offset_into_current_page_data);
+
+			bytes_processed += page_len;
+
+			last_seg_sg = current_seg_sg;
+			current_seg_sg = sg_next(current_seg_sg);
+			current_xfer_sg = sg_next(current_xfer_sg);
+
+			/* only the first page may require additional offset. */
+			offset_into_current_page_data = 0;
+			nents++;
+		}
+
+		/* update num_sgs and terminate the list since we may have
+		 *  concatenated pages. */
+		sg_mark_end(last_seg_sg);
+		*out_num_sgs = nents;
+	}
+
+	return out_sg;
+}
+
+/*
+ * Populate DMA buffer info for the isoc dto urb.
+ */
+static void __wa_populate_dto_urb_isoc(struct wa_xfer *xfer,
+	struct wa_seg *seg, int curr_iso_frame)
+{
+	seg->dto_urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
+	seg->dto_urb->sg = NULL;
+	seg->dto_urb->num_sgs = 0;
+	/* dto urb buffer address pulled from iso_frame_desc. */
+	seg->dto_urb->transfer_dma = xfer->urb->transfer_dma +
+		xfer->urb->iso_frame_desc[curr_iso_frame].offset;
+	/* The Alereon HWA sends a single URB with all isoc segs. */
+	if (xfer->wa->quirks & WUSB_QUIRK_ALEREON_HWA_CONCAT_ISOC)
+		seg->dto_urb->transfer_buffer_length = seg->isoc_size;
+	else
+		seg->dto_urb->transfer_buffer_length =
+			xfer->urb->iso_frame_desc[curr_iso_frame].length;
+}
+
+/*
+ * Populate buffer ptr and size, DMA buffer or SG list for the dto urb.
+ */
+static int __wa_populate_dto_urb(struct wa_xfer *xfer,
+	struct wa_seg *seg, size_t buf_itr_offset, size_t buf_itr_size)
+{
+	int result = 0;
+
+	if (xfer->is_dma) {
+		seg->dto_urb->transfer_dma =
+			xfer->urb->transfer_dma + buf_itr_offset;
+		seg->dto_urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
+		seg->dto_urb->sg = NULL;
+		seg->dto_urb->num_sgs = 0;
+	} else {
+		/* do buffer or SG processing. */
+		seg->dto_urb->transfer_flags &=
+			~URB_NO_TRANSFER_DMA_MAP;
+		/* this should always be 0 before a resubmit. */
+		seg->dto_urb->num_mapped_sgs = 0;
+
+		if (xfer->urb->transfer_buffer) {
+			seg->dto_urb->transfer_buffer =
+				xfer->urb->transfer_buffer +
+				buf_itr_offset;
+			seg->dto_urb->sg = NULL;
+			seg->dto_urb->num_sgs = 0;
+		} else {
+			seg->dto_urb->transfer_buffer = NULL;
+
+			/*
+			 * allocate an SG list to store seg_size bytes
+			 * and copy the subset of the xfer->urb->sg that
+			 * matches the buffer subset we are about to
+			 * read.
+			 */
+			seg->dto_urb->sg = wa_xfer_create_subset_sg(
+				xfer->urb->sg,
+				buf_itr_offset, buf_itr_size,
+				&(seg->dto_urb->num_sgs));
+			if (!(seg->dto_urb->sg))
+				result = -ENOMEM;
+		}
+	}
+	seg->dto_urb->transfer_buffer_length = buf_itr_size;
+
+	return result;
+}
+
+/*
+ * Allocate the segs array and initialize each of them
+ *
+ * The segments are freed by wa_xfer_destroy() when the xfer use count
+ * drops to zero; however, because each segment is given the same life
+ * cycle as the USB URB it contains, it is actually freed by
+ * usb_put_urb() on the contained USB URB (twisted, eh?).
+ */
+static int __wa_xfer_setup_segs(struct wa_xfer *xfer, size_t xfer_hdr_size)
+{
+	int result, cnt, isoc_frame_offset = 0;
+	size_t alloc_size = sizeof(*xfer->seg[0])
+		- sizeof(xfer->seg[0]->xfer_hdr) + xfer_hdr_size;
+	struct usb_device *usb_dev = xfer->wa->usb_dev;
+	const struct usb_endpoint_descriptor *dto_epd = xfer->wa->dto_epd;
+	struct wa_seg *seg;
+	size_t buf_itr, buf_size, buf_itr_size;
+
+	result = -ENOMEM;
+	xfer->seg = kcalloc(xfer->segs, sizeof(xfer->seg[0]), GFP_ATOMIC);
+	if (xfer->seg == NULL)
+		goto error_segs_kzalloc;
+	buf_itr = 0;
+	buf_size = xfer->urb->transfer_buffer_length;
+	for (cnt = 0; cnt < xfer->segs; cnt++) {
+		size_t iso_pkt_descr_size = 0;
+		int seg_isoc_frame_count = 0, seg_isoc_size = 0;
+
+		/*
+		 * Adjust the size of the segment object to contain space for
+		 * the isoc packet descriptor buffer.
+		 */
+		if (usb_pipeisoc(xfer->urb->pipe)) {
+			seg_isoc_frame_count =
+				__wa_seg_calculate_isoc_frame_count(xfer,
+					isoc_frame_offset, &seg_isoc_size);
+
+			iso_pkt_descr_size =
+				sizeof(struct wa_xfer_packet_info_hwaiso) +
+				(seg_isoc_frame_count * sizeof(__le16));
+		}
+		result = -ENOMEM;
+		seg = xfer->seg[cnt] = kmalloc(alloc_size + iso_pkt_descr_size,
+						GFP_ATOMIC);
+		if (seg == NULL)
+			goto error_seg_kmalloc;
+		wa_seg_init(seg);
+		seg->xfer = xfer;
+		seg->index = cnt;
+		usb_fill_bulk_urb(&seg->tr_urb, usb_dev,
+				  usb_sndbulkpipe(usb_dev,
+						  dto_epd->bEndpointAddress),
+				  &seg->xfer_hdr, xfer_hdr_size,
+				  wa_seg_tr_cb, seg);
+		buf_itr_size = min(buf_size, xfer->seg_size);
+
+		if (usb_pipeisoc(xfer->urb->pipe)) {
+			seg->isoc_frame_count = seg_isoc_frame_count;
+			seg->isoc_frame_offset = isoc_frame_offset;
+			seg->isoc_size = seg_isoc_size;
+			/* iso packet descriptor. */
+			seg->isoc_pack_desc_urb =
+					usb_alloc_urb(0, GFP_ATOMIC);
+			if (seg->isoc_pack_desc_urb == NULL)
+				goto error_iso_pack_desc_alloc;
+			/*
+			 * The buffer for the isoc packet descriptor starts
+			 * after the transfer request header in the
+			 * segment object memory buffer.
+			 */
+			usb_fill_bulk_urb(
+				seg->isoc_pack_desc_urb, usb_dev,
+				usb_sndbulkpipe(usb_dev,
+					dto_epd->bEndpointAddress),
+				(void *)(&seg->xfer_hdr) +
+					xfer_hdr_size,
+				iso_pkt_descr_size,
+				wa_seg_iso_pack_desc_cb, seg);
+
+			/* adjust starting frame offset for next seg. */
+			isoc_frame_offset += seg_isoc_frame_count;
+		}
+
+		if (xfer->is_inbound == 0 && buf_size > 0) {
+			/* outbound data. */
+			seg->dto_urb = usb_alloc_urb(0, GFP_ATOMIC);
+			if (seg->dto_urb == NULL)
+				goto error_dto_alloc;
+			usb_fill_bulk_urb(
+				seg->dto_urb, usb_dev,
+				usb_sndbulkpipe(usb_dev,
+						dto_epd->bEndpointAddress),
+				NULL, 0, wa_seg_dto_cb, seg);
+
+			if (usb_pipeisoc(xfer->urb->pipe)) {
+				/*
+				 * Fill in the xfer buffer information for the
+				 * first isoc frame.  Subsequent frames in this
+				 * segment will be filled in and sent from the
+				 * DTO completion routine, if needed.
+				 */
+				__wa_populate_dto_urb_isoc(xfer, seg,
+					seg->isoc_frame_offset);
+			} else {
+				/* fill in the xfer buffer information. */
+				result = __wa_populate_dto_urb(xfer, seg,
+							buf_itr, buf_itr_size);
+				if (result < 0)
+					goto error_seg_outbound_populate;
+
+				buf_itr += buf_itr_size;
+				buf_size -= buf_itr_size;
+			}
+		}
+		seg->status = WA_SEG_READY;
+	}
+	return 0;
+
+	/*
+	 * Free the memory for the current segment which failed to init.
+	 * Use the fact that cnt is left at were it failed.  The remaining
+	 * segments will be cleaned up by wa_xfer_destroy.
+	 */
+error_seg_outbound_populate:
+	usb_free_urb(xfer->seg[cnt]->dto_urb);
+error_dto_alloc:
+	usb_free_urb(xfer->seg[cnt]->isoc_pack_desc_urb);
+error_iso_pack_desc_alloc:
+	kfree(xfer->seg[cnt]);
+	xfer->seg[cnt] = NULL;
+error_seg_kmalloc:
+error_segs_kzalloc:
+	return result;
+}
+
+/*
+ * Allocates all the stuff needed to submit a transfer
+ *
+ * Breaks the whole data buffer in a list of segments, each one has a
+ * structure allocated to it and linked in xfer->seg[index]
+ *
+ * FIXME: merge setup_segs() and the last part of this function, no
+ *        need to do two for loops when we could run everything in a
+ *        single one
+ */
+static int __wa_xfer_setup(struct wa_xfer *xfer, struct urb *urb)
+{
+	int result;
+	struct device *dev = &xfer->wa->usb_iface->dev;
+	enum wa_xfer_type xfer_type = 0; /* shut up GCC */
+	size_t xfer_hdr_size, cnt, transfer_size;
+	struct wa_xfer_hdr *xfer_hdr0, *xfer_hdr;
+
+	result = __wa_xfer_setup_sizes(xfer, &xfer_type);
+	if (result < 0)
+		goto error_setup_sizes;
+	xfer_hdr_size = result;
+	result = __wa_xfer_setup_segs(xfer, xfer_hdr_size);
+	if (result < 0) {
+		dev_err(dev, "xfer %p: Failed to allocate %d segments: %d\n",
+			xfer, xfer->segs, result);
+		goto error_setup_segs;
+	}
+	/* Fill the first header */
+	xfer_hdr0 = &xfer->seg[0]->xfer_hdr;
+	wa_xfer_id_init(xfer);
+	__wa_xfer_setup_hdr0(xfer, xfer_hdr0, xfer_type, xfer_hdr_size);
+
+	/* Fill remaining headers */
+	xfer_hdr = xfer_hdr0;
+	if (xfer_type == WA_XFER_TYPE_ISO) {
+		xfer_hdr0->dwTransferLength =
+			cpu_to_le32(xfer->seg[0]->isoc_size);
+		for (cnt = 1; cnt < xfer->segs; cnt++) {
+			struct wa_xfer_packet_info_hwaiso *packet_desc;
+			struct wa_seg *seg = xfer->seg[cnt];
+			struct wa_xfer_hwaiso *xfer_iso;
+
+			xfer_hdr = &seg->xfer_hdr;
+			xfer_iso = container_of(xfer_hdr,
+						struct wa_xfer_hwaiso, hdr);
+			packet_desc = ((void *)xfer_hdr) + xfer_hdr_size;
+			/*
+			 * Copy values from the 0th header. Segment specific
+			 * values are set below.
+			 */
+			memcpy(xfer_hdr, xfer_hdr0, xfer_hdr_size);
+			xfer_hdr->bTransferSegment = cnt;
+			xfer_hdr->dwTransferLength =
+				cpu_to_le32(seg->isoc_size);
+			xfer_iso->dwNumOfPackets =
+					cpu_to_le32(seg->isoc_frame_count);
+			__wa_setup_isoc_packet_descr(packet_desc, xfer, seg);
+			seg->status = WA_SEG_READY;
+		}
+	} else {
+		transfer_size = urb->transfer_buffer_length;
+		xfer_hdr0->dwTransferLength = transfer_size > xfer->seg_size ?
+			cpu_to_le32(xfer->seg_size) :
+			cpu_to_le32(transfer_size);
+		transfer_size -=  xfer->seg_size;
+		for (cnt = 1; cnt < xfer->segs; cnt++) {
+			xfer_hdr = &xfer->seg[cnt]->xfer_hdr;
+			memcpy(xfer_hdr, xfer_hdr0, xfer_hdr_size);
+			xfer_hdr->bTransferSegment = cnt;
+			xfer_hdr->dwTransferLength =
+				transfer_size > xfer->seg_size ?
+					cpu_to_le32(xfer->seg_size)
+					: cpu_to_le32(transfer_size);
+			xfer->seg[cnt]->status = WA_SEG_READY;
+			transfer_size -=  xfer->seg_size;
+		}
+	}
+	xfer_hdr->bTransferSegment |= 0x80;	/* this is the last segment */
+	result = 0;
+error_setup_segs:
+error_setup_sizes:
+	return result;
+}
+
+/*
+ *
+ *
+ * rpipe->seg_lock is held!
+ */
+static int __wa_seg_submit(struct wa_rpipe *rpipe, struct wa_xfer *xfer,
+			   struct wa_seg *seg, int *dto_done)
+{
+	int result;
+
+	/* default to done unless we encounter a multi-frame isoc segment. */
+	*dto_done = 1;
+
+	/*
+	 * Take a ref for each segment urb so the xfer cannot disappear until
+	 * all of the callbacks run.
+	 */
+	wa_xfer_get(xfer);
+	/* submit the transfer request. */
+	seg->status = WA_SEG_SUBMITTED;
+	result = usb_submit_urb(&seg->tr_urb, GFP_ATOMIC);
+	if (result < 0) {
+		pr_err("%s: xfer %p#%u: REQ submit failed: %d\n",
+		       __func__, xfer, seg->index, result);
+		wa_xfer_put(xfer);
+		goto error_tr_submit;
+	}
+	/* submit the isoc packet descriptor if present. */
+	if (seg->isoc_pack_desc_urb) {
+		wa_xfer_get(xfer);
+		result = usb_submit_urb(seg->isoc_pack_desc_urb, GFP_ATOMIC);
+		seg->isoc_frame_index = 0;
+		if (result < 0) {
+			pr_err("%s: xfer %p#%u: ISO packet descriptor submit failed: %d\n",
+			       __func__, xfer, seg->index, result);
+			wa_xfer_put(xfer);
+			goto error_iso_pack_desc_submit;
+		}
+	}
+	/* submit the out data if this is an out request. */
+	if (seg->dto_urb) {
+		struct wahc *wa = xfer->wa;
+		wa_xfer_get(xfer);
+		result = usb_submit_urb(seg->dto_urb, GFP_ATOMIC);
+		if (result < 0) {
+			pr_err("%s: xfer %p#%u: DTO submit failed: %d\n",
+			       __func__, xfer, seg->index, result);
+			wa_xfer_put(xfer);
+			goto error_dto_submit;
+		}
+		/*
+		 * If this segment contains more than one isoc frame, hold
+		 * onto the dto resource until we send all frames.
+		 * Only applies to non-Alereon devices.
+		 */
+		if (((wa->quirks & WUSB_QUIRK_ALEREON_HWA_CONCAT_ISOC) == 0)
+			&& (seg->isoc_frame_count > 1))
+			*dto_done = 0;
+	}
+	rpipe_avail_dec(rpipe);
+	return 0;
+
+error_dto_submit:
+	usb_unlink_urb(seg->isoc_pack_desc_urb);
+error_iso_pack_desc_submit:
+	usb_unlink_urb(&seg->tr_urb);
+error_tr_submit:
+	seg->status = WA_SEG_ERROR;
+	seg->result = result;
+	*dto_done = 1;
+	return result;
+}
+
+/*
+ * Execute more queued request segments until the maximum concurrent allowed.
+ * Return true if the DTO resource was acquired and released.
+ *
+ * The ugly unlock/lock sequence on the error path is needed as the
+ * xfer->lock normally nests the seg_lock and not viceversa.
+ */
+static int __wa_xfer_delayed_run(struct wa_rpipe *rpipe, int *dto_waiting)
+{
+	int result, dto_acquired = 0, dto_done = 0;
+	struct device *dev = &rpipe->wa->usb_iface->dev;
+	struct wa_seg *seg;
+	struct wa_xfer *xfer;
+	unsigned long flags;
+
+	*dto_waiting = 0;
+
+	spin_lock_irqsave(&rpipe->seg_lock, flags);
+	while (atomic_read(&rpipe->segs_available) > 0
+	      && !list_empty(&rpipe->seg_list)
+	      && (dto_acquired = __wa_dto_try_get(rpipe->wa))) {
+		seg = list_first_entry(&(rpipe->seg_list), struct wa_seg,
+				 list_node);
+		list_del(&seg->list_node);
+		xfer = seg->xfer;
+		/*
+		 * Get a reference to the xfer in case the callbacks for the
+		 * URBs submitted by __wa_seg_submit attempt to complete
+		 * the xfer before this function completes.
+		 */
+		wa_xfer_get(xfer);
+		result = __wa_seg_submit(rpipe, xfer, seg, &dto_done);
+		/* release the dto resource if this RPIPE is done with it. */
+		if (dto_done)
+			__wa_dto_put(rpipe->wa);
+		dev_dbg(dev, "xfer %p ID %08X#%u submitted from delayed [%d segments available] %d\n",
+			xfer, wa_xfer_id(xfer), seg->index,
+			atomic_read(&rpipe->segs_available), result);
+		if (unlikely(result < 0)) {
+			int done;
+
+			spin_unlock_irqrestore(&rpipe->seg_lock, flags);
+			spin_lock_irqsave(&xfer->lock, flags);
+			__wa_xfer_abort(xfer);
+			/*
+			 * This seg was marked as submitted when it was put on
+			 * the RPIPE seg_list.  Mark it done.
+			 */
+			xfer->segs_done++;
+			done = __wa_xfer_is_done(xfer);
+			spin_unlock_irqrestore(&xfer->lock, flags);
+			if (done)
+				wa_xfer_completion(xfer);
+			spin_lock_irqsave(&rpipe->seg_lock, flags);
+		}
+		wa_xfer_put(xfer);
+	}
+	/*
+	 * Mark this RPIPE as waiting if dto was not acquired, there are
+	 * delayed segs and no active transfers to wake us up later.
+	 */
+	if (!dto_acquired && !list_empty(&rpipe->seg_list)
+		&& (atomic_read(&rpipe->segs_available) ==
+			le16_to_cpu(rpipe->descr.wRequests)))
+		*dto_waiting = 1;
+
+	spin_unlock_irqrestore(&rpipe->seg_lock, flags);
+
+	return dto_done;
+}
+
+static void wa_xfer_delayed_run(struct wa_rpipe *rpipe)
+{
+	int dto_waiting;
+	int dto_done = __wa_xfer_delayed_run(rpipe, &dto_waiting);
+
+	/*
+	 * If this RPIPE is waiting on the DTO resource, add it to the tail of
+	 * the waiting list.
+	 * Otherwise, if the WA DTO resource was acquired and released by
+	 *  __wa_xfer_delayed_run, another RPIPE may have attempted to acquire
+	 * DTO and failed during that time.  Check the delayed list and process
+	 * any waiters.  Start searching from the next RPIPE index.
+	 */
+	if (dto_waiting)
+		wa_add_delayed_rpipe(rpipe->wa, rpipe);
+	else if (dto_done)
+		wa_check_for_delayed_rpipes(rpipe->wa);
+}
+
+/*
+ *
+ * xfer->lock is taken
+ *
+ * On failure submitting we just stop submitting and return error;
+ * wa_urb_enqueue_b() will execute the completion path
+ */
+static int __wa_xfer_submit(struct wa_xfer *xfer)
+{
+	int result, dto_acquired = 0, dto_done = 0, dto_waiting = 0;
+	struct wahc *wa = xfer->wa;
+	struct device *dev = &wa->usb_iface->dev;
+	unsigned cnt;
+	struct wa_seg *seg;
+	unsigned long flags;
+	struct wa_rpipe *rpipe = xfer->ep->hcpriv;
+	size_t maxrequests = le16_to_cpu(rpipe->descr.wRequests);
+	u8 available;
+	u8 empty;
+
+	spin_lock_irqsave(&wa->xfer_list_lock, flags);
+	list_add_tail(&xfer->list_node, &wa->xfer_list);
+	spin_unlock_irqrestore(&wa->xfer_list_lock, flags);
+
+	BUG_ON(atomic_read(&rpipe->segs_available) > maxrequests);
+	result = 0;
+	spin_lock_irqsave(&rpipe->seg_lock, flags);
+	for (cnt = 0; cnt < xfer->segs; cnt++) {
+		int delay_seg = 1;
+
+		available = atomic_read(&rpipe->segs_available);
+		empty = list_empty(&rpipe->seg_list);
+		seg = xfer->seg[cnt];
+		if (available && empty) {
+			/*
+			 * Only attempt to acquire DTO if we have a segment
+			 * to send.
+			 */
+			dto_acquired = __wa_dto_try_get(rpipe->wa);
+			if (dto_acquired) {
+				delay_seg = 0;
+				result = __wa_seg_submit(rpipe, xfer, seg,
+							&dto_done);
+				dev_dbg(dev, "xfer %p ID 0x%08X#%u: available %u empty %u submitted\n",
+					xfer, wa_xfer_id(xfer), cnt, available,
+					empty);
+				if (dto_done)
+					__wa_dto_put(rpipe->wa);
+
+				if (result < 0) {
+					__wa_xfer_abort(xfer);
+					goto error_seg_submit;
+				}
+			}
+		}
+
+		if (delay_seg) {
+			dev_dbg(dev, "xfer %p ID 0x%08X#%u: available %u empty %u delayed\n",
+				xfer, wa_xfer_id(xfer), cnt, available,  empty);
+			seg->status = WA_SEG_DELAYED;
+			list_add_tail(&seg->list_node, &rpipe->seg_list);
+		}
+		xfer->segs_submitted++;
+	}
+error_seg_submit:
+	/*
+	 * Mark this RPIPE as waiting if dto was not acquired, there are
+	 * delayed segs and no active transfers to wake us up later.
+	 */
+	if (!dto_acquired && !list_empty(&rpipe->seg_list)
+		&& (atomic_read(&rpipe->segs_available) ==
+			le16_to_cpu(rpipe->descr.wRequests)))
+		dto_waiting = 1;
+	spin_unlock_irqrestore(&rpipe->seg_lock, flags);
+
+	if (dto_waiting)
+		wa_add_delayed_rpipe(rpipe->wa, rpipe);
+	else if (dto_done)
+		wa_check_for_delayed_rpipes(rpipe->wa);
+
+	return result;
+}
+
+/*
+ * Second part of a URB/transfer enqueuement
+ *
+ * Assumes this comes from wa_urb_enqueue() [maybe through
+ * wa_urb_enqueue_run()]. At this point:
+ *
+ * xfer->wa	filled and refcounted
+ * xfer->ep	filled with rpipe refcounted if
+ *              delayed == 0
+ * xfer->urb 	filled and refcounted (this is the case when called
+ *              from wa_urb_enqueue() as we come from usb_submit_urb()
+ *              and when called by wa_urb_enqueue_run(), as we took an
+ *              extra ref dropped by _run() after we return).
+ * xfer->gfp	filled
+ *
+ * If we fail at __wa_xfer_submit(), then we just check if we are done
+ * and if so, we run the completion procedure. However, if we are not
+ * yet done, we do nothing and wait for the completion handlers from
+ * the submitted URBs or from the xfer-result path to kick in. If xfer
+ * result never kicks in, the xfer will timeout from the USB code and
+ * dequeue() will be called.
+ */
+static int wa_urb_enqueue_b(struct wa_xfer *xfer)
+{
+	int result;
+	unsigned long flags;
+	struct urb *urb = xfer->urb;
+	struct wahc *wa = xfer->wa;
+	struct wusbhc *wusbhc = wa->wusb;
+	struct wusb_dev *wusb_dev;
+	unsigned done;
+
+	result = rpipe_get_by_ep(wa, xfer->ep, urb, xfer->gfp);
+	if (result < 0) {
+		pr_err("%s: error_rpipe_get\n", __func__);
+		goto error_rpipe_get;
+	}
+	result = -ENODEV;
+	/* FIXME: segmentation broken -- kills DWA */
+	mutex_lock(&wusbhc->mutex);		/* get a WUSB dev */
+	if (urb->dev == NULL) {
+		mutex_unlock(&wusbhc->mutex);
+		pr_err("%s: error usb dev gone\n", __func__);
+		goto error_dev_gone;
+	}
+	wusb_dev = __wusb_dev_get_by_usb_dev(wusbhc, urb->dev);
+	if (wusb_dev == NULL) {
+		mutex_unlock(&wusbhc->mutex);
+		dev_err(&(urb->dev->dev), "%s: error wusb dev gone\n",
+			__func__);
+		goto error_dev_gone;
+	}
+	mutex_unlock(&wusbhc->mutex);
+
+	spin_lock_irqsave(&xfer->lock, flags);
+	xfer->wusb_dev = wusb_dev;
+	result = urb->status;
+	if (urb->status != -EINPROGRESS) {
+		dev_err(&(urb->dev->dev), "%s: error_dequeued\n", __func__);
+		goto error_dequeued;
+	}
+
+	result = __wa_xfer_setup(xfer, urb);
+	if (result < 0) {
+		dev_err(&(urb->dev->dev), "%s: error_xfer_setup\n", __func__);
+		goto error_xfer_setup;
+	}
+	/*
+	 * Get a xfer reference since __wa_xfer_submit starts asynchronous
+	 * operations that may try to complete the xfer before this function
+	 * exits.
+	 */
+	wa_xfer_get(xfer);
+	result = __wa_xfer_submit(xfer);
+	if (result < 0) {
+		dev_err(&(urb->dev->dev), "%s: error_xfer_submit\n", __func__);
+		goto error_xfer_submit;
+	}
+	spin_unlock_irqrestore(&xfer->lock, flags);
+	wa_xfer_put(xfer);
+	return 0;
+
+	/*
+	 * this is basically wa_xfer_completion() broken up wa_xfer_giveback()
+	 * does a wa_xfer_put() that will call wa_xfer_destroy() and undo
+	 * setup().
+	 */
+error_xfer_setup:
+error_dequeued:
+	spin_unlock_irqrestore(&xfer->lock, flags);
+	/* FIXME: segmentation broken, kills DWA */
+	if (wusb_dev)
+		wusb_dev_put(wusb_dev);
+error_dev_gone:
+	rpipe_put(xfer->ep->hcpriv);
+error_rpipe_get:
+	xfer->result = result;
+	return result;
+
+error_xfer_submit:
+	done = __wa_xfer_is_done(xfer);
+	xfer->result = result;
+	spin_unlock_irqrestore(&xfer->lock, flags);
+	if (done)
+		wa_xfer_completion(xfer);
+	wa_xfer_put(xfer);
+	/* return success since the completion routine will run. */
+	return 0;
+}
+
+/*
+ * Execute the delayed transfers in the Wire Adapter @wa
+ *
+ * We need to be careful here, as dequeue() could be called in the
+ * middle.  That's why we do the whole thing under the
+ * wa->xfer_list_lock. If dequeue() jumps in, it first locks xfer->lock
+ * and then checks the list -- so as we would be acquiring in inverse
+ * order, we move the delayed list to a separate list while locked and then
+ * submit them without the list lock held.
+ */
+void wa_urb_enqueue_run(struct work_struct *ws)
+{
+	struct wahc *wa = container_of(ws, struct wahc, xfer_enqueue_work);
+	struct wa_xfer *xfer, *next;
+	struct urb *urb;
+	LIST_HEAD(tmp_list);
+
+	/* Create a copy of the wa->xfer_delayed_list while holding the lock */
+	spin_lock_irq(&wa->xfer_list_lock);
+	list_cut_position(&tmp_list, &wa->xfer_delayed_list,
+			wa->xfer_delayed_list.prev);
+	spin_unlock_irq(&wa->xfer_list_lock);
+
+	/*
+	 * enqueue from temp list without list lock held since wa_urb_enqueue_b
+	 * can take xfer->lock as well as lock mutexes.
+	 */
+	list_for_each_entry_safe(xfer, next, &tmp_list, list_node) {
+		list_del_init(&xfer->list_node);
+
+		urb = xfer->urb;
+		if (wa_urb_enqueue_b(xfer) < 0)
+			wa_xfer_giveback(xfer);
+		usb_put_urb(urb);	/* taken when queuing */
+	}
+}
+EXPORT_SYMBOL_GPL(wa_urb_enqueue_run);
+
+/*
+ * Process the errored transfers on the Wire Adapter outside of interrupt.
+ */
+void wa_process_errored_transfers_run(struct work_struct *ws)
+{
+	struct wahc *wa = container_of(ws, struct wahc, xfer_error_work);
+	struct wa_xfer *xfer, *next;
+	LIST_HEAD(tmp_list);
+
+	pr_info("%s: Run delayed STALL processing.\n", __func__);
+
+	/* Create a copy of the wa->xfer_errored_list while holding the lock */
+	spin_lock_irq(&wa->xfer_list_lock);
+	list_cut_position(&tmp_list, &wa->xfer_errored_list,
+			wa->xfer_errored_list.prev);
+	spin_unlock_irq(&wa->xfer_list_lock);
+
+	/*
+	 * run rpipe_clear_feature_stalled from temp list without list lock
+	 * held.
+	 */
+	list_for_each_entry_safe(xfer, next, &tmp_list, list_node) {
+		struct usb_host_endpoint *ep;
+		unsigned long flags;
+		struct wa_rpipe *rpipe;
+
+		spin_lock_irqsave(&xfer->lock, flags);
+		ep = xfer->ep;
+		rpipe = ep->hcpriv;
+		spin_unlock_irqrestore(&xfer->lock, flags);
+
+		/* clear RPIPE feature stalled without holding a lock. */
+		rpipe_clear_feature_stalled(wa, ep);
+
+		/* complete the xfer. This removes it from the tmp list. */
+		wa_xfer_completion(xfer);
+
+		/* check for work. */
+		wa_xfer_delayed_run(rpipe);
+	}
+}
+EXPORT_SYMBOL_GPL(wa_process_errored_transfers_run);
+
+/*
+ * Submit a transfer to the Wire Adapter in a delayed way
+ *
+ * The process of enqueuing involves possible sleeps() [see
+ * enqueue_b(), for the rpipe_get() and the mutex_lock()]. If we are
+ * in an atomic section, we defer the enqueue_b() call--else we call direct.
+ *
+ * @urb: We own a reference to it done by the HCI Linux USB stack that
+ *       will be given up by calling usb_hcd_giveback_urb() or by
+ *       returning error from this function -> ergo we don't have to
+ *       refcount it.
+ */
+int wa_urb_enqueue(struct wahc *wa, struct usb_host_endpoint *ep,
+		   struct urb *urb, gfp_t gfp)
+{
+	int result;
+	struct device *dev = &wa->usb_iface->dev;
+	struct wa_xfer *xfer;
+	unsigned long my_flags;
+	unsigned cant_sleep = irqs_disabled() | in_atomic();
+
+	if ((urb->transfer_buffer == NULL)
+	    && (urb->sg == NULL)
+	    && !(urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP)
+	    && urb->transfer_buffer_length != 0) {
+		dev_err(dev, "BUG? urb %p: NULL xfer buffer & NODMA\n", urb);
+		dump_stack();
+	}
+
+	spin_lock_irqsave(&wa->xfer_list_lock, my_flags);
+	result = usb_hcd_link_urb_to_ep(&(wa->wusb->usb_hcd), urb);
+	spin_unlock_irqrestore(&wa->xfer_list_lock, my_flags);
+	if (result < 0)
+		goto error_link_urb;
+
+	result = -ENOMEM;
+	xfer = kzalloc(sizeof(*xfer), gfp);
+	if (xfer == NULL)
+		goto error_kmalloc;
+
+	result = -ENOENT;
+	if (urb->status != -EINPROGRESS)	/* cancelled */
+		goto error_dequeued;		/* before starting? */
+	wa_xfer_init(xfer);
+	xfer->wa = wa_get(wa);
+	xfer->urb = urb;
+	xfer->gfp = gfp;
+	xfer->ep = ep;
+	urb->hcpriv = xfer;
+
+	dev_dbg(dev, "xfer %p urb %p pipe 0x%02x [%d bytes] %s %s %s\n",
+		xfer, urb, urb->pipe, urb->transfer_buffer_length,
+		urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP ? "dma" : "nodma",
+		urb->pipe & USB_DIR_IN ? "inbound" : "outbound",
+		cant_sleep ? "deferred" : "inline");
+
+	if (cant_sleep) {
+		usb_get_urb(urb);
+		spin_lock_irqsave(&wa->xfer_list_lock, my_flags);
+		list_add_tail(&xfer->list_node, &wa->xfer_delayed_list);
+		spin_unlock_irqrestore(&wa->xfer_list_lock, my_flags);
+		queue_work(wusbd, &wa->xfer_enqueue_work);
+	} else {
+		result = wa_urb_enqueue_b(xfer);
+		if (result < 0) {
+			/*
+			 * URB submit/enqueue failed.  Clean up, return an
+			 * error and do not run the callback.  This avoids
+			 * an infinite submit/complete loop.
+			 */
+			dev_err(dev, "%s: URB enqueue failed: %d\n",
+			   __func__, result);
+			wa_put(xfer->wa);
+			wa_xfer_put(xfer);
+			spin_lock_irqsave(&wa->xfer_list_lock, my_flags);
+			usb_hcd_unlink_urb_from_ep(&(wa->wusb->usb_hcd), urb);
+			spin_unlock_irqrestore(&wa->xfer_list_lock, my_flags);
+			return result;
+		}
+	}
+	return 0;
+
+error_dequeued:
+	kfree(xfer);
+error_kmalloc:
+	spin_lock_irqsave(&wa->xfer_list_lock, my_flags);
+	usb_hcd_unlink_urb_from_ep(&(wa->wusb->usb_hcd), urb);
+	spin_unlock_irqrestore(&wa->xfer_list_lock, my_flags);
+error_link_urb:
+	return result;
+}
+EXPORT_SYMBOL_GPL(wa_urb_enqueue);
+
+/*
+ * Dequeue a URB and make sure uwb_hcd_giveback_urb() [completion
+ * handler] is called.
+ *
+ * Until a transfer goes successfully through wa_urb_enqueue() it
+ * needs to be dequeued with completion calling; when stuck in delayed
+ * or before wa_xfer_setup() is called, we need to do completion.
+ *
+ *  not setup  If there is no hcpriv yet, that means that that enqueue
+ *             still had no time to set the xfer up. Because
+ *             urb->status should be other than -EINPROGRESS,
+ *             enqueue() will catch that and bail out.
+ *
+ * If the transfer has gone through setup, we just need to clean it
+ * up. If it has gone through submit(), we have to abort it [with an
+ * asynch request] and then make sure we cancel each segment.
+ *
+ */
+int wa_urb_dequeue(struct wahc *wa, struct urb *urb, int status)
+{
+	unsigned long flags;
+	struct wa_xfer *xfer;
+	struct wa_seg *seg;
+	struct wa_rpipe *rpipe;
+	unsigned cnt, done = 0, xfer_abort_pending;
+	unsigned rpipe_ready = 0;
+	int result;
+
+	/* check if it is safe to unlink. */
+	spin_lock_irqsave(&wa->xfer_list_lock, flags);
+	result = usb_hcd_check_unlink_urb(&(wa->wusb->usb_hcd), urb, status);
+	if ((result == 0) && urb->hcpriv) {
+		/*
+		 * Get a xfer ref to prevent a race with wa_xfer_giveback
+		 * cleaning up the xfer while we are working with it.
+		 */
+		wa_xfer_get(urb->hcpriv);
+	}
+	spin_unlock_irqrestore(&wa->xfer_list_lock, flags);
+	if (result)
+		return result;
+
+	xfer = urb->hcpriv;
+	if (xfer == NULL)
+		return -ENOENT;
+	spin_lock_irqsave(&xfer->lock, flags);
+	pr_debug("%s: DEQUEUE xfer id 0x%08X\n", __func__, wa_xfer_id(xfer));
+	rpipe = xfer->ep->hcpriv;
+	if (rpipe == NULL) {
+		pr_debug("%s: xfer %p id 0x%08X has no RPIPE.  %s",
+			__func__, xfer, wa_xfer_id(xfer),
+			"Probably already aborted.\n" );
+		result = -ENOENT;
+		goto out_unlock;
+	}
+	/*
+	 * Check for done to avoid racing with wa_xfer_giveback and completing
+	 * twice.
+	 */
+	if (__wa_xfer_is_done(xfer)) {
+		pr_debug("%s: xfer %p id 0x%08X already done.\n", __func__,
+			xfer, wa_xfer_id(xfer));
+		result = -ENOENT;
+		goto out_unlock;
+	}
+	/* Check the delayed list -> if there, release and complete */
+	spin_lock(&wa->xfer_list_lock);
+	if (!list_empty(&xfer->list_node) && xfer->seg == NULL)
+		goto dequeue_delayed;
+	spin_unlock(&wa->xfer_list_lock);
+	if (xfer->seg == NULL)  	/* still hasn't reached */
+		goto out_unlock;	/* setup(), enqueue_b() completes */
+	/* Ok, the xfer is in flight already, it's been setup and submitted.*/
+	xfer_abort_pending = __wa_xfer_abort(xfer) >= 0;
+	/*
+	 * grab the rpipe->seg_lock here to prevent racing with
+	 * __wa_xfer_delayed_run.
+	 */
+	spin_lock(&rpipe->seg_lock);
+	for (cnt = 0; cnt < xfer->segs; cnt++) {
+		seg = xfer->seg[cnt];
+		pr_debug("%s: xfer id 0x%08X#%d status = %d\n",
+			__func__, wa_xfer_id(xfer), cnt, seg->status);
+		switch (seg->status) {
+		case WA_SEG_NOTREADY:
+		case WA_SEG_READY:
+			printk(KERN_ERR "xfer %p#%u: dequeue bad state %u\n",
+			       xfer, cnt, seg->status);
+			WARN_ON(1);
+			break;
+		case WA_SEG_DELAYED:
+			/*
+			 * delete from rpipe delayed list.  If no segments on
+			 * this xfer have been submitted, __wa_xfer_is_done will
+			 * trigger a giveback below.  Otherwise, the submitted
+			 * segments will be completed in the DTI interrupt.
+			 */
+			seg->status = WA_SEG_ABORTED;
+			seg->result = -ENOENT;
+			list_del(&seg->list_node);
+			xfer->segs_done++;
+			break;
+		case WA_SEG_DONE:
+		case WA_SEG_ERROR:
+		case WA_SEG_ABORTED:
+			break;
+			/*
+			 * The buf_in data for a segment in the
+			 * WA_SEG_DTI_PENDING state is actively being read.
+			 * Let wa_buf_in_cb handle it since it will be called
+			 * and will increment xfer->segs_done.  Cleaning up
+			 * here could cause wa_buf_in_cb to access the xfer
+			 * after it has been completed/freed.
+			 */
+		case WA_SEG_DTI_PENDING:
+			break;
+			/*
+			 * In the states below, the HWA device already knows
+			 * about the transfer.  If an abort request was sent,
+			 * allow the HWA to process it and wait for the
+			 * results.  Otherwise, the DTI state and seg completed
+			 * counts can get out of sync.
+			 */
+		case WA_SEG_SUBMITTED:
+		case WA_SEG_PENDING:
+			/*
+			 * Check if the abort was successfully sent.  This could
+			 * be false if the HWA has been removed but we haven't
+			 * gotten the disconnect notification yet.
+			 */
+			if (!xfer_abort_pending) {
+				seg->status = WA_SEG_ABORTED;
+				rpipe_ready = rpipe_avail_inc(rpipe);
+				xfer->segs_done++;
+			}
+			break;
+		}
+	}
+	spin_unlock(&rpipe->seg_lock);
+	xfer->result = urb->status;	/* -ENOENT or -ECONNRESET */
+	done = __wa_xfer_is_done(xfer);
+	spin_unlock_irqrestore(&xfer->lock, flags);
+	if (done)
+		wa_xfer_completion(xfer);
+	if (rpipe_ready)
+		wa_xfer_delayed_run(rpipe);
+	wa_xfer_put(xfer);
+	return result;
+
+out_unlock:
+	spin_unlock_irqrestore(&xfer->lock, flags);
+	wa_xfer_put(xfer);
+	return result;
+
+dequeue_delayed:
+	list_del_init(&xfer->list_node);
+	spin_unlock(&wa->xfer_list_lock);
+	xfer->result = urb->status;
+	spin_unlock_irqrestore(&xfer->lock, flags);
+	wa_xfer_giveback(xfer);
+	wa_xfer_put(xfer);
+	usb_put_urb(urb);		/* we got a ref in enqueue() */
+	return 0;
+}
+EXPORT_SYMBOL_GPL(wa_urb_dequeue);
+
+/*
+ * Translation from WA status codes (WUSB1.0 Table 8.15) to errno
+ * codes
+ *
+ * Positive errno values are internal inconsistencies and should be
+ * flagged louder. Negative are to be passed up to the user in the
+ * normal way.
+ *
+ * @status: USB WA status code -- high two bits are stripped.
+ */
+static int wa_xfer_status_to_errno(u8 status)
+{
+	int errno;
+	u8 real_status = status;
+	static int xlat[] = {
+		[WA_XFER_STATUS_SUCCESS] = 		0,
+		[WA_XFER_STATUS_HALTED] = 		-EPIPE,
+		[WA_XFER_STATUS_DATA_BUFFER_ERROR] = 	-ENOBUFS,
+		[WA_XFER_STATUS_BABBLE] = 		-EOVERFLOW,
+		[WA_XFER_RESERVED] = 			EINVAL,
+		[WA_XFER_STATUS_NOT_FOUND] =		0,
+		[WA_XFER_STATUS_INSUFFICIENT_RESOURCE] = -ENOMEM,
+		[WA_XFER_STATUS_TRANSACTION_ERROR] = 	-EILSEQ,
+		[WA_XFER_STATUS_ABORTED] =		-ENOENT,
+		[WA_XFER_STATUS_RPIPE_NOT_READY] = 	EINVAL,
+		[WA_XFER_INVALID_FORMAT] = 		EINVAL,
+		[WA_XFER_UNEXPECTED_SEGMENT_NUMBER] = 	EINVAL,
+		[WA_XFER_STATUS_RPIPE_TYPE_MISMATCH] = 	EINVAL,
+	};
+	status &= 0x3f;
+
+	if (status == 0)
+		return 0;
+	if (status >= ARRAY_SIZE(xlat)) {
+		printk_ratelimited(KERN_ERR "%s(): BUG? "
+			       "Unknown WA transfer status 0x%02x\n",
+			       __func__, real_status);
+		return -EINVAL;
+	}
+	errno = xlat[status];
+	if (unlikely(errno > 0)) {
+		printk_ratelimited(KERN_ERR "%s(): BUG? "
+			       "Inconsistent WA status: 0x%02x\n",
+			       __func__, real_status);
+		errno = -errno;
+	}
+	return errno;
+}
+
+/*
+ * If a last segment flag and/or a transfer result error is encountered,
+ * no other segment transfer results will be returned from the device.
+ * Mark the remaining submitted or pending xfers as completed so that
+ * the xfer will complete cleanly.
+ *
+ * xfer->lock must be held
+ *
+ */
+static void wa_complete_remaining_xfer_segs(struct wa_xfer *xfer,
+		int starting_index, enum wa_seg_status status)
+{
+	int index;
+	struct wa_rpipe *rpipe = xfer->ep->hcpriv;
+
+	for (index = starting_index; index < xfer->segs_submitted; index++) {
+		struct wa_seg *current_seg = xfer->seg[index];
+
+		BUG_ON(current_seg == NULL);
+
+		switch (current_seg->status) {
+		case WA_SEG_SUBMITTED:
+		case WA_SEG_PENDING:
+		case WA_SEG_DTI_PENDING:
+			rpipe_avail_inc(rpipe);
+		/*
+		 * do not increment RPIPE avail for the WA_SEG_DELAYED case
+		 * since it has not been submitted to the RPIPE.
+		 */
+		/* fall through */
+		case WA_SEG_DELAYED:
+			xfer->segs_done++;
+			current_seg->status = status;
+			break;
+		case WA_SEG_ABORTED:
+			break;
+		default:
+			WARN(1, "%s: xfer 0x%08X#%d. bad seg status = %d\n",
+				__func__, wa_xfer_id(xfer), index,
+				current_seg->status);
+			break;
+		}
+	}
+}
+
+/* Populate the given urb based on the current isoc transfer state. */
+static int __wa_populate_buf_in_urb_isoc(struct wahc *wa,
+	struct urb *buf_in_urb, struct wa_xfer *xfer, struct wa_seg *seg)
+{
+	int urb_start_frame = seg->isoc_frame_index + seg->isoc_frame_offset;
+	int seg_index, total_len = 0, urb_frame_index = urb_start_frame;
+	struct usb_iso_packet_descriptor *iso_frame_desc =
+						xfer->urb->iso_frame_desc;
+	const int dti_packet_size = usb_endpoint_maxp(wa->dti_epd);
+	int next_frame_contiguous;
+	struct usb_iso_packet_descriptor *iso_frame;
+
+	BUG_ON(buf_in_urb->status == -EINPROGRESS);
+
+	/*
+	 * If the current frame actual_length is contiguous with the next frame
+	 * and actual_length is a multiple of the DTI endpoint max packet size,
+	 * combine the current frame with the next frame in a single URB.  This
+	 * reduces the number of URBs that must be submitted in that case.
+	 */
+	seg_index = seg->isoc_frame_index;
+	do {
+		next_frame_contiguous = 0;
+
+		iso_frame = &iso_frame_desc[urb_frame_index];
+		total_len += iso_frame->actual_length;
+		++urb_frame_index;
+		++seg_index;
+
+		if (seg_index < seg->isoc_frame_count) {
+			struct usb_iso_packet_descriptor *next_iso_frame;
+
+			next_iso_frame = &iso_frame_desc[urb_frame_index];
+
+			if ((iso_frame->offset + iso_frame->actual_length) ==
+				next_iso_frame->offset)
+				next_frame_contiguous = 1;
+		}
+	} while (next_frame_contiguous
+			&& ((iso_frame->actual_length % dti_packet_size) == 0));
+
+	/* this should always be 0 before a resubmit. */
+	buf_in_urb->num_mapped_sgs	= 0;
+	buf_in_urb->transfer_dma = xfer->urb->transfer_dma +
+		iso_frame_desc[urb_start_frame].offset;
+	buf_in_urb->transfer_buffer_length = total_len;
+	buf_in_urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
+	buf_in_urb->transfer_buffer = NULL;
+	buf_in_urb->sg = NULL;
+	buf_in_urb->num_sgs = 0;
+	buf_in_urb->context = seg;
+
+	/* return the number of frames included in this URB. */
+	return seg_index - seg->isoc_frame_index;
+}
+
+/* Populate the given urb based on the current transfer state. */
+static int wa_populate_buf_in_urb(struct urb *buf_in_urb, struct wa_xfer *xfer,
+	unsigned int seg_idx, unsigned int bytes_transferred)
+{
+	int result = 0;
+	struct wa_seg *seg = xfer->seg[seg_idx];
+
+	BUG_ON(buf_in_urb->status == -EINPROGRESS);
+	/* this should always be 0 before a resubmit. */
+	buf_in_urb->num_mapped_sgs	= 0;
+
+	if (xfer->is_dma) {
+		buf_in_urb->transfer_dma = xfer->urb->transfer_dma
+			+ (seg_idx * xfer->seg_size);
+		buf_in_urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
+		buf_in_urb->transfer_buffer = NULL;
+		buf_in_urb->sg = NULL;
+		buf_in_urb->num_sgs = 0;
+	} else {
+		/* do buffer or SG processing. */
+		buf_in_urb->transfer_flags &= ~URB_NO_TRANSFER_DMA_MAP;
+
+		if (xfer->urb->transfer_buffer) {
+			buf_in_urb->transfer_buffer =
+				xfer->urb->transfer_buffer
+				+ (seg_idx * xfer->seg_size);
+			buf_in_urb->sg = NULL;
+			buf_in_urb->num_sgs = 0;
+		} else {
+			/* allocate an SG list to store seg_size bytes
+				and copy the subset of the xfer->urb->sg
+				that matches the buffer subset we are
+				about to read. */
+			buf_in_urb->sg = wa_xfer_create_subset_sg(
+				xfer->urb->sg,
+				seg_idx * xfer->seg_size,
+				bytes_transferred,
+				&(buf_in_urb->num_sgs));
+
+			if (!(buf_in_urb->sg)) {
+				buf_in_urb->num_sgs	= 0;
+				result = -ENOMEM;
+			}
+			buf_in_urb->transfer_buffer = NULL;
+		}
+	}
+	buf_in_urb->transfer_buffer_length = bytes_transferred;
+	buf_in_urb->context = seg;
+
+	return result;
+}
+
+/*
+ * Process a xfer result completion message
+ *
+ * inbound transfers: need to schedule a buf_in_urb read
+ *
+ * FIXME: this function needs to be broken up in parts
+ */
+static void wa_xfer_result_chew(struct wahc *wa, struct wa_xfer *xfer,
+		struct wa_xfer_result *xfer_result)
+{
+	int result;
+	struct device *dev = &wa->usb_iface->dev;
+	unsigned long flags;
+	unsigned int seg_idx;
+	struct wa_seg *seg;
+	struct wa_rpipe *rpipe;
+	unsigned done = 0;
+	u8 usb_status;
+	unsigned rpipe_ready = 0;
+	unsigned bytes_transferred = le32_to_cpu(xfer_result->dwTransferLength);
+	struct urb *buf_in_urb = &(wa->buf_in_urbs[0]);
+
+	spin_lock_irqsave(&xfer->lock, flags);
+	seg_idx = xfer_result->bTransferSegment & 0x7f;
+	if (unlikely(seg_idx >= xfer->segs))
+		goto error_bad_seg;
+	seg = xfer->seg[seg_idx];
+	rpipe = xfer->ep->hcpriv;
+	usb_status = xfer_result->bTransferStatus;
+	dev_dbg(dev, "xfer %p ID 0x%08X#%u: bTransferStatus 0x%02x (seg status %u)\n",
+		xfer, wa_xfer_id(xfer), seg_idx, usb_status, seg->status);
+	if (seg->status == WA_SEG_ABORTED
+	    || seg->status == WA_SEG_ERROR)	/* already handled */
+		goto segment_aborted;
+	if (seg->status == WA_SEG_SUBMITTED)	/* ops, got here */
+		seg->status = WA_SEG_PENDING;	/* before wa_seg{_dto}_cb() */
+	if (seg->status != WA_SEG_PENDING) {
+		if (printk_ratelimit())
+			dev_err(dev, "xfer %p#%u: Bad segment state %u\n",
+				xfer, seg_idx, seg->status);
+		seg->status = WA_SEG_PENDING;	/* workaround/"fix" it */
+	}
+	if (usb_status & 0x80) {
+		seg->result = wa_xfer_status_to_errno(usb_status);
+		dev_err(dev, "DTI: xfer %p 0x%08X:#%u failed (0x%02x)\n",
+			xfer, xfer->id, seg->index, usb_status);
+		seg->status = ((usb_status & 0x7F) == WA_XFER_STATUS_ABORTED) ?
+			WA_SEG_ABORTED : WA_SEG_ERROR;
+		goto error_complete;
+	}
+	/* FIXME: we ignore warnings, tally them for stats */
+	if (usb_status & 0x40) 		/* Warning?... */
+		usb_status = 0;		/* ... pass */
+	/*
+	 * If the last segment bit is set, complete the remaining segments.
+	 * When the current segment is completed, either in wa_buf_in_cb for
+	 * transfers with data or below for no data, the xfer will complete.
+	 */
+	if (xfer_result->bTransferSegment & 0x80)
+		wa_complete_remaining_xfer_segs(xfer, seg->index + 1,
+			WA_SEG_DONE);
+	if (usb_pipeisoc(xfer->urb->pipe)
+		&& (le32_to_cpu(xfer_result->dwNumOfPackets) > 0)) {
+		/* set up WA state to read the isoc packet status next. */
+		wa->dti_isoc_xfer_in_progress = wa_xfer_id(xfer);
+		wa->dti_isoc_xfer_seg = seg_idx;
+		wa->dti_state = WA_DTI_ISOC_PACKET_STATUS_PENDING;
+	} else if (xfer->is_inbound && !usb_pipeisoc(xfer->urb->pipe)
+			&& (bytes_transferred > 0)) {
+		/* IN data phase: read to buffer */
+		seg->status = WA_SEG_DTI_PENDING;
+		result = wa_populate_buf_in_urb(buf_in_urb, xfer, seg_idx,
+			bytes_transferred);
+		if (result < 0)
+			goto error_buf_in_populate;
+		++(wa->active_buf_in_urbs);
+		result = usb_submit_urb(buf_in_urb, GFP_ATOMIC);
+		if (result < 0) {
+			--(wa->active_buf_in_urbs);
+			goto error_submit_buf_in;
+		}
+	} else {
+		/* OUT data phase or no data, complete it -- */
+		seg->result = bytes_transferred;
+		rpipe_ready = rpipe_avail_inc(rpipe);
+		done = __wa_xfer_mark_seg_as_done(xfer, seg, WA_SEG_DONE);
+	}
+	spin_unlock_irqrestore(&xfer->lock, flags);
+	if (done)
+		wa_xfer_completion(xfer);
+	if (rpipe_ready)
+		wa_xfer_delayed_run(rpipe);
+	return;
+
+error_submit_buf_in:
+	if (edc_inc(&wa->dti_edc, EDC_MAX_ERRORS, EDC_ERROR_TIMEFRAME)) {
+		dev_err(dev, "DTI: URB max acceptable errors "
+			"exceeded, resetting device\n");
+		wa_reset_all(wa);
+	}
+	if (printk_ratelimit())
+		dev_err(dev, "xfer %p#%u: can't submit DTI data phase: %d\n",
+			xfer, seg_idx, result);
+	seg->result = result;
+	kfree(buf_in_urb->sg);
+	buf_in_urb->sg = NULL;
+error_buf_in_populate:
+	__wa_xfer_abort(xfer);
+	seg->status = WA_SEG_ERROR;
+error_complete:
+	xfer->segs_done++;
+	rpipe_ready = rpipe_avail_inc(rpipe);
+	wa_complete_remaining_xfer_segs(xfer, seg->index + 1, seg->status);
+	done = __wa_xfer_is_done(xfer);
+	/*
+	 * queue work item to clear STALL for control endpoints.
+	 * Otherwise, let endpoint_reset take care of it.
+	 */
+	if (((usb_status & 0x3f) == WA_XFER_STATUS_HALTED) &&
+		usb_endpoint_xfer_control(&xfer->ep->desc) &&
+		done) {
+
+		dev_info(dev, "Control EP stall.  Queue delayed work.\n");
+		spin_lock(&wa->xfer_list_lock);
+		/* move xfer from xfer_list to xfer_errored_list. */
+		list_move_tail(&xfer->list_node, &wa->xfer_errored_list);
+		spin_unlock(&wa->xfer_list_lock);
+		spin_unlock_irqrestore(&xfer->lock, flags);
+		queue_work(wusbd, &wa->xfer_error_work);
+	} else {
+		spin_unlock_irqrestore(&xfer->lock, flags);
+		if (done)
+			wa_xfer_completion(xfer);
+		if (rpipe_ready)
+			wa_xfer_delayed_run(rpipe);
+	}
+
+	return;
+
+error_bad_seg:
+	spin_unlock_irqrestore(&xfer->lock, flags);
+	wa_urb_dequeue(wa, xfer->urb, -ENOENT);
+	if (printk_ratelimit())
+		dev_err(dev, "xfer %p#%u: bad segment\n", xfer, seg_idx);
+	if (edc_inc(&wa->dti_edc, EDC_MAX_ERRORS, EDC_ERROR_TIMEFRAME)) {
+		dev_err(dev, "DTI: URB max acceptable errors "
+			"exceeded, resetting device\n");
+		wa_reset_all(wa);
+	}
+	return;
+
+segment_aborted:
+	/* nothing to do, as the aborter did the completion */
+	spin_unlock_irqrestore(&xfer->lock, flags);
+}
+
+/*
+ * Process a isochronous packet status message
+ *
+ * inbound transfers: need to schedule a buf_in_urb read
+ */
+static int wa_process_iso_packet_status(struct wahc *wa, struct urb *urb)
+{
+	struct device *dev = &wa->usb_iface->dev;
+	struct wa_xfer_packet_status_hwaiso *packet_status;
+	struct wa_xfer_packet_status_len_hwaiso *status_array;
+	struct wa_xfer *xfer;
+	unsigned long flags;
+	struct wa_seg *seg;
+	struct wa_rpipe *rpipe;
+	unsigned done = 0, dti_busy = 0, data_frame_count = 0, seg_index;
+	unsigned first_frame_index = 0, rpipe_ready = 0;
+	size_t expected_size;
+
+	/* We have a xfer result buffer; check it */
+	dev_dbg(dev, "DTI: isoc packet status %d bytes at %p\n",
+		urb->actual_length, urb->transfer_buffer);
+	packet_status = (struct wa_xfer_packet_status_hwaiso *)(wa->dti_buf);
+	if (packet_status->bPacketType != WA_XFER_ISO_PACKET_STATUS) {
+		dev_err(dev, "DTI Error: isoc packet status--bad type 0x%02x\n",
+			packet_status->bPacketType);
+		goto error_parse_buffer;
+	}
+	xfer = wa_xfer_get_by_id(wa, wa->dti_isoc_xfer_in_progress);
+	if (xfer == NULL) {
+		dev_err(dev, "DTI Error: isoc packet status--unknown xfer 0x%08x\n",
+			wa->dti_isoc_xfer_in_progress);
+		goto error_parse_buffer;
+	}
+	spin_lock_irqsave(&xfer->lock, flags);
+	if (unlikely(wa->dti_isoc_xfer_seg >= xfer->segs))
+		goto error_bad_seg;
+	seg = xfer->seg[wa->dti_isoc_xfer_seg];
+	rpipe = xfer->ep->hcpriv;
+	expected_size = struct_size(packet_status, PacketStatus,
+				    seg->isoc_frame_count);
+	if (urb->actual_length != expected_size) {
+		dev_err(dev, "DTI Error: isoc packet status--bad urb length (%d bytes vs %zu needed)\n",
+			urb->actual_length, expected_size);
+		goto error_bad_seg;
+	}
+	if (le16_to_cpu(packet_status->wLength) != expected_size) {
+		dev_err(dev, "DTI Error: isoc packet status--bad length %u\n",
+			le16_to_cpu(packet_status->wLength));
+		goto error_bad_seg;
+	}
+	/* write isoc packet status and lengths back to the xfer urb. */
+	status_array = packet_status->PacketStatus;
+	xfer->urb->start_frame =
+		wa->wusb->usb_hcd.driver->get_frame_number(&wa->wusb->usb_hcd);
+	for (seg_index = 0; seg_index < seg->isoc_frame_count; ++seg_index) {
+		struct usb_iso_packet_descriptor *iso_frame_desc =
+			xfer->urb->iso_frame_desc;
+		const int xfer_frame_index =
+			seg->isoc_frame_offset + seg_index;
+
+		iso_frame_desc[xfer_frame_index].status =
+			wa_xfer_status_to_errno(
+			le16_to_cpu(status_array[seg_index].PacketStatus));
+		iso_frame_desc[xfer_frame_index].actual_length =
+			le16_to_cpu(status_array[seg_index].PacketLength);
+		/* track the number of frames successfully transferred. */
+		if (iso_frame_desc[xfer_frame_index].actual_length > 0) {
+			/* save the starting frame index for buf_in_urb. */
+			if (!data_frame_count)
+				first_frame_index = seg_index;
+			++data_frame_count;
+		}
+	}
+
+	if (xfer->is_inbound && data_frame_count) {
+		int result, total_frames_read = 0, urb_index = 0;
+		struct urb *buf_in_urb;
+
+		/* IN data phase: read to buffer */
+		seg->status = WA_SEG_DTI_PENDING;
+
+		/* start with the first frame with data. */
+		seg->isoc_frame_index = first_frame_index;
+		/* submit up to WA_MAX_BUF_IN_URBS read URBs. */
+		do {
+			int urb_frame_index, urb_frame_count;
+			struct usb_iso_packet_descriptor *iso_frame_desc;
+
+			buf_in_urb = &(wa->buf_in_urbs[urb_index]);
+			urb_frame_count = __wa_populate_buf_in_urb_isoc(wa,
+				buf_in_urb, xfer, seg);
+			/* advance frame index to start of next read URB. */
+			seg->isoc_frame_index += urb_frame_count;
+			total_frames_read += urb_frame_count;
+
+			++(wa->active_buf_in_urbs);
+			result = usb_submit_urb(buf_in_urb, GFP_ATOMIC);
+
+			/* skip 0-byte frames. */
+			urb_frame_index =
+				seg->isoc_frame_offset + seg->isoc_frame_index;
+			iso_frame_desc =
+				&(xfer->urb->iso_frame_desc[urb_frame_index]);
+			while ((seg->isoc_frame_index <
+						seg->isoc_frame_count) &&
+				 (iso_frame_desc->actual_length == 0)) {
+				++(seg->isoc_frame_index);
+				++iso_frame_desc;
+			}
+			++urb_index;
+
+		} while ((result == 0) && (urb_index < WA_MAX_BUF_IN_URBS)
+				&& (seg->isoc_frame_index <
+						seg->isoc_frame_count));
+
+		if (result < 0) {
+			--(wa->active_buf_in_urbs);
+			dev_err(dev, "DTI Error: Could not submit buf in URB (%d)",
+				result);
+			wa_reset_all(wa);
+		} else if (data_frame_count > total_frames_read)
+			/* If we need to read more frames, set DTI busy. */
+			dti_busy = 1;
+	} else {
+		/* OUT transfer or no more IN data, complete it -- */
+		rpipe_ready = rpipe_avail_inc(rpipe);
+		done = __wa_xfer_mark_seg_as_done(xfer, seg, WA_SEG_DONE);
+	}
+	spin_unlock_irqrestore(&xfer->lock, flags);
+	if (dti_busy)
+		wa->dti_state = WA_DTI_BUF_IN_DATA_PENDING;
+	else
+		wa->dti_state = WA_DTI_TRANSFER_RESULT_PENDING;
+	if (done)
+		wa_xfer_completion(xfer);
+	if (rpipe_ready)
+		wa_xfer_delayed_run(rpipe);
+	wa_xfer_put(xfer);
+	return dti_busy;
+
+error_bad_seg:
+	spin_unlock_irqrestore(&xfer->lock, flags);
+	wa_xfer_put(xfer);
+error_parse_buffer:
+	return dti_busy;
+}
+
+/*
+ * Callback for the IN data phase
+ *
+ * If successful transition state; otherwise, take a note of the
+ * error, mark this segment done and try completion.
+ *
+ * Note we don't access until we are sure that the transfer hasn't
+ * been cancelled (ECONNRESET, ENOENT), which could mean that
+ * seg->xfer could be already gone.
+ */
+static void wa_buf_in_cb(struct urb *urb)
+{
+	struct wa_seg *seg = urb->context;
+	struct wa_xfer *xfer = seg->xfer;
+	struct wahc *wa;
+	struct device *dev;
+	struct wa_rpipe *rpipe;
+	unsigned rpipe_ready = 0, isoc_data_frame_count = 0;
+	unsigned long flags;
+	int resubmit_dti = 0, active_buf_in_urbs;
+	u8 done = 0;
+
+	/* free the sg if it was used. */
+	kfree(urb->sg);
+	urb->sg = NULL;
+
+	spin_lock_irqsave(&xfer->lock, flags);
+	wa = xfer->wa;
+	dev = &wa->usb_iface->dev;
+	--(wa->active_buf_in_urbs);
+	active_buf_in_urbs = wa->active_buf_in_urbs;
+	rpipe = xfer->ep->hcpriv;
+
+	if (usb_pipeisoc(xfer->urb->pipe)) {
+		struct usb_iso_packet_descriptor *iso_frame_desc =
+			xfer->urb->iso_frame_desc;
+		int	seg_index;
+
+		/*
+		 * Find the next isoc frame with data and count how many
+		 * frames with data remain.
+		 */
+		seg_index = seg->isoc_frame_index;
+		while (seg_index < seg->isoc_frame_count) {
+			const int urb_frame_index =
+				seg->isoc_frame_offset + seg_index;
+
+			if (iso_frame_desc[urb_frame_index].actual_length > 0) {
+				/* save the index of the next frame with data */
+				if (!isoc_data_frame_count)
+					seg->isoc_frame_index = seg_index;
+				++isoc_data_frame_count;
+			}
+			++seg_index;
+		}
+	}
+	spin_unlock_irqrestore(&xfer->lock, flags);
+
+	switch (urb->status) {
+	case 0:
+		spin_lock_irqsave(&xfer->lock, flags);
+
+		seg->result += urb->actual_length;
+		if (isoc_data_frame_count > 0) {
+			int result, urb_frame_count;
+
+			/* submit a read URB for the next frame with data. */
+			urb_frame_count = __wa_populate_buf_in_urb_isoc(wa, urb,
+				 xfer, seg);
+			/* advance index to start of next read URB. */
+			seg->isoc_frame_index += urb_frame_count;
+			++(wa->active_buf_in_urbs);
+			result = usb_submit_urb(urb, GFP_ATOMIC);
+			if (result < 0) {
+				--(wa->active_buf_in_urbs);
+				dev_err(dev, "DTI Error: Could not submit buf in URB (%d)",
+					result);
+				wa_reset_all(wa);
+			}
+			/*
+			 * If we are in this callback and
+			 * isoc_data_frame_count > 0, it means that the dti_urb
+			 * submission was delayed in wa_dti_cb.  Once
+			 * we submit the last buf_in_urb, we can submit the
+			 * delayed dti_urb.
+			 */
+			  resubmit_dti = (isoc_data_frame_count ==
+							urb_frame_count);
+		} else if (active_buf_in_urbs == 0) {
+			dev_dbg(dev,
+				"xfer %p 0x%08X#%u: data in done (%zu bytes)\n",
+				xfer, wa_xfer_id(xfer), seg->index,
+				seg->result);
+			rpipe_ready = rpipe_avail_inc(rpipe);
+			done = __wa_xfer_mark_seg_as_done(xfer, seg,
+					WA_SEG_DONE);
+		}
+		spin_unlock_irqrestore(&xfer->lock, flags);
+		if (done)
+			wa_xfer_completion(xfer);
+		if (rpipe_ready)
+			wa_xfer_delayed_run(rpipe);
+		break;
+	case -ECONNRESET:	/* URB unlinked; no need to do anything */
+	case -ENOENT:		/* as it was done by the who unlinked us */
+		break;
+	default:		/* Other errors ... */
+		/*
+		 * Error on data buf read.  Only resubmit DTI if it hasn't
+		 * already been done by previously hitting this error or by a
+		 * successful completion of the previous buf_in_urb.
+		 */
+		resubmit_dti = wa->dti_state != WA_DTI_TRANSFER_RESULT_PENDING;
+		spin_lock_irqsave(&xfer->lock, flags);
+		if (printk_ratelimit())
+			dev_err(dev, "xfer %p 0x%08X#%u: data in error %d\n",
+				xfer, wa_xfer_id(xfer), seg->index,
+				urb->status);
+		if (edc_inc(&wa->nep_edc, EDC_MAX_ERRORS,
+			    EDC_ERROR_TIMEFRAME)){
+			dev_err(dev, "DTO: URB max acceptable errors "
+				"exceeded, resetting device\n");
+			wa_reset_all(wa);
+		}
+		seg->result = urb->status;
+		rpipe_ready = rpipe_avail_inc(rpipe);
+		if (active_buf_in_urbs == 0)
+			done = __wa_xfer_mark_seg_as_done(xfer, seg,
+				WA_SEG_ERROR);
+		else
+			__wa_xfer_abort(xfer);
+		spin_unlock_irqrestore(&xfer->lock, flags);
+		if (done)
+			wa_xfer_completion(xfer);
+		if (rpipe_ready)
+			wa_xfer_delayed_run(rpipe);
+	}
+
+	if (resubmit_dti) {
+		int result;
+
+		wa->dti_state = WA_DTI_TRANSFER_RESULT_PENDING;
+
+		result = usb_submit_urb(wa->dti_urb, GFP_ATOMIC);
+		if (result < 0) {
+			dev_err(dev, "DTI Error: Could not submit DTI URB (%d)\n",
+				result);
+			wa_reset_all(wa);
+		}
+	}
+}
+
+/*
+ * Handle an incoming transfer result buffer
+ *
+ * Given a transfer result buffer, it completes the transfer (possibly
+ * scheduling and buffer in read) and then resubmits the DTI URB for a
+ * new transfer result read.
+ *
+ *
+ * The xfer_result DTI URB state machine
+ *
+ * States: OFF | RXR (Read-Xfer-Result) | RBI (Read-Buffer-In)
+ *
+ * We start in OFF mode, the first xfer_result notification [through
+ * wa_handle_notif_xfer()] moves us to RXR by posting the DTI-URB to
+ * read.
+ *
+ * We receive a buffer -- if it is not a xfer_result, we complain and
+ * repost the DTI-URB. If it is a xfer_result then do the xfer seg
+ * request accounting. If it is an IN segment, we move to RBI and post
+ * a BUF-IN-URB to the right buffer. The BUF-IN-URB callback will
+ * repost the DTI-URB and move to RXR state. if there was no IN
+ * segment, it will repost the DTI-URB.
+ *
+ * We go back to OFF when we detect a ENOENT or ESHUTDOWN (or too many
+ * errors) in the URBs.
+ */
+static void wa_dti_cb(struct urb *urb)
+{
+	int result, dti_busy = 0;
+	struct wahc *wa = urb->context;
+	struct device *dev = &wa->usb_iface->dev;
+	u32 xfer_id;
+	u8 usb_status;
+
+	BUG_ON(wa->dti_urb != urb);
+	switch (wa->dti_urb->status) {
+	case 0:
+		if (wa->dti_state == WA_DTI_TRANSFER_RESULT_PENDING) {
+			struct wa_xfer_result *xfer_result;
+			struct wa_xfer *xfer;
+
+			/* We have a xfer result buffer; check it */
+			dev_dbg(dev, "DTI: xfer result %d bytes at %p\n",
+				urb->actual_length, urb->transfer_buffer);
+			if (urb->actual_length != sizeof(*xfer_result)) {
+				dev_err(dev, "DTI Error: xfer result--bad size xfer result (%d bytes vs %zu needed)\n",
+					urb->actual_length,
+					sizeof(*xfer_result));
+				break;
+			}
+			xfer_result = (struct wa_xfer_result *)(wa->dti_buf);
+			if (xfer_result->hdr.bLength != sizeof(*xfer_result)) {
+				dev_err(dev, "DTI Error: xfer result--bad header length %u\n",
+					xfer_result->hdr.bLength);
+				break;
+			}
+			if (xfer_result->hdr.bNotifyType != WA_XFER_RESULT) {
+				dev_err(dev, "DTI Error: xfer result--bad header type 0x%02x\n",
+					xfer_result->hdr.bNotifyType);
+				break;
+			}
+			xfer_id = le32_to_cpu(xfer_result->dwTransferID);
+			usb_status = xfer_result->bTransferStatus & 0x3f;
+			if (usb_status == WA_XFER_STATUS_NOT_FOUND) {
+				/* taken care of already */
+				dev_dbg(dev, "%s: xfer 0x%08X#%u not found.\n",
+					__func__, xfer_id,
+					xfer_result->bTransferSegment & 0x7f);
+				break;
+			}
+			xfer = wa_xfer_get_by_id(wa, xfer_id);
+			if (xfer == NULL) {
+				/* FIXME: transaction not found. */
+				dev_err(dev, "DTI Error: xfer result--unknown xfer 0x%08x (status 0x%02x)\n",
+					xfer_id, usb_status);
+				break;
+			}
+			wa_xfer_result_chew(wa, xfer, xfer_result);
+			wa_xfer_put(xfer);
+		} else if (wa->dti_state == WA_DTI_ISOC_PACKET_STATUS_PENDING) {
+			dti_busy = wa_process_iso_packet_status(wa, urb);
+		} else {
+			dev_err(dev, "DTI Error: unexpected EP state = %d\n",
+				wa->dti_state);
+		}
+		break;
+	case -ENOENT:		/* (we killed the URB)...so, no broadcast */
+	case -ESHUTDOWN:	/* going away! */
+		dev_dbg(dev, "DTI: going down! %d\n", urb->status);
+		goto out;
+	default:
+		/* Unknown error */
+		if (edc_inc(&wa->dti_edc, EDC_MAX_ERRORS,
+			    EDC_ERROR_TIMEFRAME)) {
+			dev_err(dev, "DTI: URB max acceptable errors "
+				"exceeded, resetting device\n");
+			wa_reset_all(wa);
+			goto out;
+		}
+		if (printk_ratelimit())
+			dev_err(dev, "DTI: URB error %d\n", urb->status);
+		break;
+	}
+
+	/* Resubmit the DTI URB if we are not busy processing isoc in frames. */
+	if (!dti_busy) {
+		result = usb_submit_urb(wa->dti_urb, GFP_ATOMIC);
+		if (result < 0) {
+			dev_err(dev, "DTI Error: Could not submit DTI URB (%d)\n",
+				result);
+			wa_reset_all(wa);
+		}
+	}
+out:
+	return;
+}
+
+/*
+ * Initialize the DTI URB for reading transfer result notifications and also
+ * the buffer-in URB, for reading buffers. Then we just submit the DTI URB.
+ */
+int wa_dti_start(struct wahc *wa)
+{
+	const struct usb_endpoint_descriptor *dti_epd = wa->dti_epd;
+	struct device *dev = &wa->usb_iface->dev;
+	int result = -ENOMEM, index;
+
+	if (wa->dti_urb != NULL)	/* DTI URB already started */
+		goto out;
+
+	wa->dti_urb = usb_alloc_urb(0, GFP_KERNEL);
+	if (wa->dti_urb == NULL)
+		goto error_dti_urb_alloc;
+	usb_fill_bulk_urb(
+		wa->dti_urb, wa->usb_dev,
+		usb_rcvbulkpipe(wa->usb_dev, 0x80 | dti_epd->bEndpointAddress),
+		wa->dti_buf, wa->dti_buf_size,
+		wa_dti_cb, wa);
+
+	/* init the buf in URBs */
+	for (index = 0; index < WA_MAX_BUF_IN_URBS; ++index) {
+		usb_fill_bulk_urb(
+			&(wa->buf_in_urbs[index]), wa->usb_dev,
+			usb_rcvbulkpipe(wa->usb_dev,
+				0x80 | dti_epd->bEndpointAddress),
+			NULL, 0, wa_buf_in_cb, wa);
+	}
+	result = usb_submit_urb(wa->dti_urb, GFP_KERNEL);
+	if (result < 0) {
+		dev_err(dev, "DTI Error: Could not submit DTI URB (%d) resetting\n",
+			result);
+		goto error_dti_urb_submit;
+	}
+out:
+	return 0;
+
+error_dti_urb_submit:
+	usb_put_urb(wa->dti_urb);
+	wa->dti_urb = NULL;
+error_dti_urb_alloc:
+	return result;
+}
+EXPORT_SYMBOL_GPL(wa_dti_start);
+/*
+ * Transfer complete notification
+ *
+ * Called from the notif.c code. We get a notification on EP2 saying
+ * that some endpoint has some transfer result data available. We are
+ * about to read it.
+ *
+ * To speed up things, we always have a URB reading the DTI URB; we
+ * don't really set it up and start it until the first xfer complete
+ * notification arrives, which is what we do here.
+ *
+ * Follow up in wa_dti_cb(), as that's where the whole state
+ * machine starts.
+ *
+ * @wa shall be referenced
+ */
+void wa_handle_notif_xfer(struct wahc *wa, struct wa_notif_hdr *notif_hdr)
+{
+	struct device *dev = &wa->usb_iface->dev;
+	struct wa_notif_xfer *notif_xfer;
+	const struct usb_endpoint_descriptor *dti_epd = wa->dti_epd;
+
+	notif_xfer = container_of(notif_hdr, struct wa_notif_xfer, hdr);
+	BUG_ON(notif_hdr->bNotifyType != WA_NOTIF_TRANSFER);
+
+	if ((0x80 | notif_xfer->bEndpoint) != dti_epd->bEndpointAddress) {
+		/* FIXME: hardcoded limitation, adapt */
+		dev_err(dev, "BUG: DTI ep is %u, not %u (hack me)\n",
+			notif_xfer->bEndpoint, dti_epd->bEndpointAddress);
+		goto error;
+	}
+
+	/* attempt to start the DTI ep processing. */
+	if (wa_dti_start(wa) < 0)
+		goto error;
+
+	return;
+
+error:
+	wa_reset_all(wa);
+}