[PATCH] UHCI: remove main list of URBs

As part of reorienting uhci-hcd away from URBs and toward endpoint
queues, this patch (as625) eliminates the driver's main list of URBs.
The list wsa used mainly in checking for URB completions; now the driver
goes through the list of active endpoints and checks the members of the
queues.

As a side effect, I had to remove the code that looks for FSBR timeouts.
For now, FSBR will remain on so long as any URBs on a full-speed control
or bulk queue request it, even if the queue isn't advancing.  A later
patch can add more intelligent handling.  This isn't a huge drawback;
it's pretty rare for an URB to get stuck for more than a fraction of a
second.  (And it will help the people trying to use those insane HP USB
devices.)

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 274 insertions, 357 deletions

diff --git a/drivers/usb/host/uhci-q.c b/drivers/usb/host/uhci-q.c
index c4194182dcc4..44bba9a6d196 100644
--- a/drivers/usb/host/uhci-q.c
+++ b/drivers/usb/host/uhci-q.c
@@ -151,53 +151,6 @@ static void uhci_unlink_isochronous_tds(struct uhci_hcd *uhci, struct urb *urb)
         wmb();
 }
 
-/*
- * Remove an URB's TDs from the hardware schedule
- */
-static void uhci_remove_tds_from_schedule(struct uhci_hcd *uhci,
-                struct urb *urb, int status)
-{
-        struct urb_priv *urbp = (struct urb_priv *) urb->hcpriv;
-
-        /* Isochronous TDs get unlinked directly from the frame list */
-        if (usb_pipetype(urb->pipe) == PIPE_ISOCHRONOUS) {
-                uhci_unlink_isochronous_tds(uhci, urb);
-                return;
-        }
-
-        /* If the URB isn't first on its queue, adjust the link pointer
-         * of the last TD in the previous URB. */
-        if (urbp->node.prev != &urbp->qh->queue) {
-                struct urb_priv *purbp;
-                struct uhci_td *ptd, *ltd;
-
-                if (status == -EINPROGRESS)
-                        status = 0;
-                purbp = list_entry(urbp->node.prev, struct urb_priv, node);
-                ptd = list_entry(purbp->td_list.prev, struct uhci_td,
-                                list);
-                ltd = list_entry(urbp->td_list.prev, struct uhci_td,
-                                list);
-                ptd->link = ltd->link;
-        }
-
-        /* If the URB completed with an error, then the QH element certainly
-         * points to one of the URB's TDs.  If it completed normally then
-         * the QH element has certainly moved on to the next URB.  And if
-         * the URB is still in progress then it must have been dequeued.
-         * The QH element either hasn't reached it yet or is somewhere in
-         * the middle.  If the URB wasn't first we can assume that it
-         * hasn't started yet (see above): Otherwise all the preceding URBs
-         * would have completed and been removed from the queue, so this one
-         * _would_ be first.
-         *
-         * If the QH element is inside this URB, clear it.  It will be
-         * set properly when the QH is activated.
-         */
-        if (status < 0)
-                urbp->qh->element = UHCI_PTR_TERM;
-}
-
 static struct uhci_qh *uhci_alloc_qh(struct uhci_hcd *uhci,
                 struct usb_device *udev, struct usb_host_endpoint *hep)
 {
@@ -251,6 +204,90 @@ static void uhci_free_qh(struct uhci_hcd *uhci, struct uhci_qh *qh)
 }
 
 /*
+ * When the currently executing URB is dequeued, save its current toggle value
+ */
+static void uhci_save_toggle(struct uhci_qh *qh, struct urb *urb)
+{
+        struct urb_priv *urbp = (struct urb_priv *) urb->hcpriv;
+        struct uhci_td *td;
+
+        /* If the QH element pointer is UHCI_PTR_TERM then then currently
+         * executing URB has already been unlinked, so this one isn't it. */
+        if (qh_element(qh) == UHCI_PTR_TERM ||
+                                qh->queue.next != &urbp->node)
+                return;
+        qh->element = UHCI_PTR_TERM;
+
+        /* Only bulk and interrupt pipes have to worry about toggles */
+        if (!(usb_pipetype(urb->pipe) == PIPE_BULK ||
+                        usb_pipetype(urb->pipe) == PIPE_INTERRUPT))
+                return;
+
+        /* Find the first active TD; that's the device's toggle state */
+        list_for_each_entry(td, &urbp->td_list, list) {
+                if (td_status(td) & TD_CTRL_ACTIVE) {
+                        qh->needs_fixup = 1;
+                        qh->initial_toggle = uhci_toggle(td_token(td));
+                        return;
+                }
+        }
+
+        WARN_ON(1);
+}
+
+/*
+ * Fix up the data toggles for URBs in a queue, when one of them
+ * terminates early (short transfer, error, or dequeued).
+ */
+static void uhci_fixup_toggles(struct uhci_qh *qh, int skip_first)
+{
+        struct urb_priv *urbp = NULL;
+        struct uhci_td *td;
+        unsigned int toggle = qh->initial_toggle;
+        unsigned int pipe;
+
+        /* Fixups for a short transfer start with the second URB in the
+         * queue (the short URB is the first). */
+        if (skip_first)
+                urbp = list_entry(qh->queue.next, struct urb_priv, node);
+
+        /* When starting with the first URB, if the QH element pointer is
+         * still valid then we know the URB's toggles are okay. */
+        else if (qh_element(qh) != UHCI_PTR_TERM)
+                toggle = 2;
+
+        /* Fix up the toggle for the URBs in the queue.  Normally this
+         * loop won't run more than once: When an error or short transfer
+         * occurs, the queue usually gets emptied. */
+        list_prepare_entry(urbp, &qh->queue, node);
+        list_for_each_entry_continue(urbp, &qh->queue, node) {
+
+                /* If the first TD has the right toggle value, we don't
+                 * need to change any toggles in this URB */
+                td = list_entry(urbp->td_list.next, struct uhci_td, list);
+                if (toggle > 1 || uhci_toggle(td_token(td)) == toggle) {
+                        td = list_entry(urbp->td_list.next, struct uhci_td,
+                                        list);
+                        toggle = uhci_toggle(td_token(td)) ^ 1;
+
+                /* Otherwise all the toggles in the URB have to be switched */
+                } else {
+                        list_for_each_entry(td, &urbp->td_list, list) {
+                                td->token ^= __constant_cpu_to_le32(
+                                                        TD_TOKEN_TOGGLE);
+                                toggle ^= 1;
+                        }
+                }
+        }
+
+        wmb();
+        pipe = list_entry(qh->queue.next, struct urb_priv, node)->urb->pipe;
+        usb_settoggle(qh->udev, usb_pipeendpoint(pipe),
+                        usb_pipeout(pipe), toggle);
+        qh->needs_fixup = 0;
+}
+
+/*
  * Put a QH on the schedule in both hardware and software
  */
 static void uhci_activate_qh(struct uhci_hcd *uhci, struct uhci_qh *qh)
@@ -276,6 +313,9 @@ static void uhci_activate_qh(struct uhci_hcd *uhci, struct uhci_qh *qh)
 
         /* Move the QH from its old list to the end of the appropriate
          * skeleton's list */
+        if (qh == uhci->next_qh)
+                uhci->next_qh = list_entry(qh->node.next, struct uhci_qh,
+                                node);
         list_move_tail(&qh->node, &qh->skel->node);
 
         /* Link it into the schedule */
@@ -310,6 +350,9 @@ static void uhci_unlink_qh(struct uhci_hcd *uhci, struct uhci_qh *qh)
                 uhci_set_next_interrupt(uhci);
 
         /* Move the QH from its old list to the end of the unlinking list */
+        if (qh == uhci->next_qh)
+                uhci->next_qh = list_entry(qh->node.next, struct uhci_qh,
+                                node);
         list_move_tail(&qh->node, &uhci->skel_unlink_qh->node);
 }
 
@@ -323,6 +366,9 @@ static void uhci_make_qh_idle(struct uhci_hcd *uhci, struct uhci_qh *qh)
 {
         WARN_ON(qh->state == QH_STATE_ACTIVE);
 
+        if (qh == uhci->next_qh)
+                uhci->next_qh = list_entry(qh->node.next, struct uhci_qh,
+                                node);
         list_move(&qh->node, &uhci->idle_qh_list);
         qh->state = QH_STATE_IDLE;
 
@@ -344,11 +390,9 @@ static inline struct urb_priv *uhci_alloc_urb_priv(struct uhci_hcd *uhci,
 
         urbp->urb = urb;
         urb->hcpriv = urbp;
-        urbp->fsbrtime = jiffies;
         
         INIT_LIST_HEAD(&urbp->node);
         INIT_LIST_HEAD(&urbp->td_list);
-        INIT_LIST_HEAD(&urbp->urb_list);
 
         return urbp;
 }
@@ -373,9 +417,6 @@ static void uhci_free_urb_priv(struct uhci_hcd *uhci,
 {
         struct uhci_td *td, *tmp;
 
-        if (!list_empty(&urbp->urb_list))
-                dev_warn(uhci_dev(uhci), "urb %p still on uhci->urb_list!\n",
-                                urbp->urb);
         if (!list_empty(&urbp->node))
                 dev_warn(uhci_dev(uhci), "urb %p still on QH's list!\n",
                                 urbp->urb);
@@ -453,71 +494,6 @@ static int uhci_map_status(int status, int dir_out)
 }
 
 /*
- * Fix up the data toggles for URBs in a queue, when one of them
- * terminates early (short transfer, error, or dequeued).
- */
-static void uhci_fixup_toggles(struct urb *urb)
-{
-        struct list_head *head;
-        struct uhci_td *td;
-        struct urb_priv *urbp = (struct urb_priv *) urb->hcpriv;
-        int prevactive = 0;
-        unsigned int toggle = 0;
-        struct urb_priv *turbp, *list_end;
-
-        /*
-         * We need to find out what the last successful toggle was so
-         * we can update the data toggles for the following transfers.
-         *
-         * There are 2 ways the last successful completed TD is found:
-         *
-         * 1) The TD is NOT active and the actual length < expected length
-         * 2) The TD is NOT active and it's the last TD in the chain
-         *
-         * and a third way the first uncompleted TD is found:
-         *
-         * 3) The TD is active and the previous TD is NOT active
-         */
-        head = &urbp->td_list;
-        list_for_each_entry(td, head, list) {
-                unsigned int ctrlstat = td_status(td);
-
-                if (!(ctrlstat & TD_CTRL_ACTIVE) &&
-                                (uhci_actual_length(ctrlstat) <
-                                 uhci_expected_length(td_token(td)) ||
-                                td->list.next == head))
-                        toggle = uhci_toggle(td_token(td)) ^ 1;
-                else if ((ctrlstat & TD_CTRL_ACTIVE) && !prevactive)
-                        toggle = uhci_toggle(td_token(td));
-
-                prevactive = ctrlstat & TD_CTRL_ACTIVE;
-        }
-
-        /*
-         * Fix up the toggle for the following URBs in the queue.
-         *
-         * We can stop as soon as we find an URB with toggles set correctly,
-         * because then all the following URBs will be correct also.
-         */
-        list_end = list_entry(&urbp->qh->queue, struct urb_priv, node);
-        turbp = urbp;
-        while ((turbp = list_entry(turbp->node.next, struct urb_priv, node))
-                        != list_end) {
-                td = list_entry(turbp->td_list.next, struct uhci_td, list);
-                if (uhci_toggle(td_token(td)) == toggle)
-                        return;
-
-                list_for_each_entry(td, &turbp->td_list, list) {
-                        td->token ^= __constant_cpu_to_le32(TD_TOKEN_TOGGLE);
-                        toggle ^= 1;
-                }
-        }
-
-        usb_settoggle(urb->dev, usb_pipeendpoint(urb->pipe),
-                        usb_pipeout(urb->pipe), toggle);
-}
-
-/*
  * Control transfers
  */
 static int uhci_submit_control(struct uhci_hcd *uhci, struct urb *urb,
@@ -765,6 +741,9 @@ err:
                 }
         }
 
+        /* Note that the queue has stopped */
+        urbp->qh->element = UHCI_PTR_TERM;
+        urbp->qh->is_stopped = 1;
         return ret;
 }
 
@@ -927,7 +906,10 @@ static int uhci_result_common(struct uhci_hcd *uhci, struct urb *urb)
                          */
                         if (!urbp->short_transfer) {
                                 urbp->short_transfer = 1;
-                                uhci_fixup_toggles(urb);
+                                urbp->qh->initial_toggle =
+                                                uhci_toggle(td_token(td)) ^ 1;
+                                uhci_fixup_toggles(urbp->qh, 1);
+
                                 td = list_entry(urbp->td_list.prev,
                                                 struct uhci_td, list);
                                 urbp->qh->element = td->link;
@@ -962,6 +944,13 @@ err:
                 }
         }
 #endif
+
+        /* Note that the queue has stopped and save the next toggle value */
+        urbp->qh->element = UHCI_PTR_TERM;
+        urbp->qh->is_stopped = 1;
+        urbp->qh->needs_fixup = 1;
+        urbp->qh->initial_toggle = uhci_toggle(td_token(td)) ^
+                        (ret == -EREMOTEIO);
         return ret;
 }
 
@@ -995,76 +984,39 @@ static inline int uhci_submit_interrupt(struct uhci_hcd *uhci, struct urb *urb,
 /*
  * Isochronous transfers
  */
-static int isochronous_find_limits(struct uhci_hcd *uhci, struct urb *urb, unsigned int *start, unsigned int *end)
-{
-        struct urb *last_urb = NULL;
-        struct urb_priv *up;
-        int ret = 0;
-
-        list_for_each_entry(up, &uhci->urb_list, urb_list) {
-                struct urb *u = up->urb;
-
-                /* look for pending URBs with identical pipe handle */
-                if ((urb->pipe == u->pipe) && (urb->dev == u->dev) &&
-                    (u->status == -EINPROGRESS) && (u != urb)) {
-                        if (!last_urb)
-                                *start = u->start_frame;
-                        last_urb = u;
-                }
-        }
-
-        if (last_urb) {
-                *end = (last_urb->start_frame + last_urb->number_of_packets *
-                                last_urb->interval) & (UHCI_NUMFRAMES-1);
-                ret = 0;
-        } else
-                ret = -1;       /* no previous urb found */
-
-        return ret;
-}
-
-static int isochronous_find_start(struct uhci_hcd *uhci, struct urb *urb)
+static int uhci_submit_isochronous(struct uhci_hcd *uhci, struct urb *urb,
+                struct uhci_qh *qh)
 {
-        int limits;
-        unsigned int start = 0, end = 0;
+        struct uhci_td *td = NULL;      /* Since urb->number_of_packets > 0 */
+        int i, frame;
+        unsigned long destination, status;
+        struct urb_priv *urbp = (struct urb_priv *) urb->hcpriv;
 
         if (urb->number_of_packets > 900)       /* 900? Why? */
                 return -EFBIG;
 
-        limits = isochronous_find_limits(uhci, urb, &start, &end);
+        status = TD_CTRL_ACTIVE | TD_CTRL_IOS;
+        destination = (urb->pipe & PIPE_DEVEP_MASK) | usb_packetid(urb->pipe);
 
+        /* Figure out the starting frame number */
         if (urb->transfer_flags & URB_ISO_ASAP) {
-                if (limits) {
+                if (list_empty(&qh->queue)) {
                         uhci_get_current_frame_number(uhci);
-                        urb->start_frame = (uhci->frame_number + 10)
-                                        & (UHCI_NUMFRAMES - 1);
-                } else
-                        urb->start_frame = end;
+                        urb->start_frame = (uhci->frame_number + 10);
+
+                } else {                /* Go right after the last one */
+                        struct urb *last_urb;
+
+                        last_urb = list_entry(qh->queue.prev,
+                                        struct urb_priv, node)->urb;
+                        urb->start_frame = (last_urb->start_frame +
+                                        last_urb->number_of_packets *
+                                        last_urb->interval);
+                }
         } else {
-                urb->start_frame &= (UHCI_NUMFRAMES - 1);
                 /* FIXME: Sanity check */
         }
-
-        return 0;
-}
-
-/*
- * Isochronous transfers
- */
-static int uhci_submit_isochronous(struct uhci_hcd *uhci, struct urb *urb,
-                struct uhci_qh *qh)
-{
-        struct uhci_td *td = NULL;      /* Since urb->number_of_packets > 0 */
-        int i, ret, frame;
-        unsigned long destination, status;
-        struct urb_priv *urbp = (struct urb_priv *) urb->hcpriv;
-
-        status = TD_CTRL_ACTIVE | TD_CTRL_IOS;
-        destination = (urb->pipe & PIPE_DEVEP_MASK) | usb_packetid(urb->pipe);
-
-        ret = isochronous_find_start(uhci, urb);
-        if (ret)
-                return ret;
+        urb->start_frame &= (UHCI_NUMFRAMES - 1);
 
         for (i = 0; i < urb->number_of_packets; i++) {
                 td = uhci_alloc_td(uhci);
@@ -1203,7 +1155,6 @@ static int uhci_urb_enqueue(struct usb_hcd *hcd,
         /* Add this URB to the QH */
         urbp->qh = qh;
         list_add_tail(&urbp->node, &qh->queue);
-        list_add_tail(&urbp->urb_list, &uhci->urb_list);
 
         /* If the new URB is the first and only one on this QH then either
          * the QH is new and idle or else it's unlinked and waiting to
@@ -1224,49 +1175,66 @@ done:
         return ret;
 }
 
+static int uhci_urb_dequeue(struct usb_hcd *hcd, struct urb *urb)
+{
+        struct uhci_hcd *uhci = hcd_to_uhci(hcd);
+        unsigned long flags;
+        struct urb_priv *urbp;
+
+        spin_lock_irqsave(&uhci->lock, flags);
+        urbp = urb->hcpriv;
+        if (!urbp)                      /* URB was never linked! */
+                goto done;
+
+        /* Remove Isochronous TDs from the frame list ASAP */
+        if (usb_pipetype(urb->pipe) == PIPE_ISOCHRONOUS)
+                uhci_unlink_isochronous_tds(uhci, urb);
+        uhci_unlink_qh(uhci, urbp->qh);
+
+done:
+        spin_unlock_irqrestore(&uhci->lock, flags);
+        return 0;
+}
+
 /*
- * Return the result of a transfer
+ * Finish unlinking an URB and give it back
  */
-static void uhci_transfer_result(struct uhci_hcd *uhci, struct urb *urb)
+static void uhci_giveback_urb(struct uhci_hcd *uhci, struct uhci_qh *qh,
+                struct urb *urb, struct pt_regs *regs)
+__releases(uhci->lock)
+__acquires(uhci->lock)
 {
-        int status;
-        int okay_to_giveback = 0;
         struct urb_priv *urbp = (struct urb_priv *) urb->hcpriv;
 
-        switch (usb_pipetype(urb->pipe)) {
-        case PIPE_CONTROL:
-                status = uhci_result_control(uhci, urb);
-                break;
-        case PIPE_ISOCHRONOUS:
-                status = uhci_result_isochronous(uhci, urb);
-                break;
-        default:        /* PIPE_BULK or PIPE_INTERRUPT */
-                status = uhci_result_common(uhci, urb);
-                break;
-        }
+        /* Isochronous TDs get unlinked directly from the frame list */
+        if (usb_pipetype(urb->pipe) == PIPE_ISOCHRONOUS)
+                uhci_unlink_isochronous_tds(uhci, urb);
 
-        spin_lock(&urb->lock);
-        if (urb->status == -EINPROGRESS) {      /* Not yet dequeued */
-                if (status != -EINPROGRESS) {   /* URB has completed */
-                        urb->status = status;
+        /* If the URB isn't first on its queue, adjust the link pointer
+         * of the last TD in the previous URB. */
+        else if (qh->queue.next != &urbp->node) {
+                struct urb_priv *purbp;
+                struct uhci_td *ptd, *ltd;
 
-                        /* If the URB got a real error (as opposed to
-                         * simply being dequeued), we don't have to
-                         * unlink the QH.  Fix this later... */
-                        if (status < 0)
-                                uhci_unlink_qh(uhci, urbp->qh);
-                        else
-                                okay_to_giveback = 1;
-                }
-        } else {                                /* Already dequeued */
-                if (urbp->qh->state == QH_STATE_UNLINKING &&
-                                uhci->frame_number + uhci->is_stopped !=
-                                urbp->qh->unlink_frame)
-                        okay_to_giveback = 1;
+                purbp = list_entry(urbp->node.prev, struct urb_priv, node);
+                ptd = list_entry(purbp->td_list.prev, struct uhci_td,
+                                list);
+                ltd = list_entry(urbp->td_list.prev, struct uhci_td,
+                                list);
+                ptd->link = ltd->link;
         }
-        spin_unlock(&urb->lock);
-        if (!okay_to_giveback)
-                return;
+
+        /* Take the URB off the QH's queue.  If the queue is now empty,
+         * this is a perfect time for a toggle fixup. */
+        list_del_init(&urbp->node);
+        if (list_empty(&qh->queue) && qh->needs_fixup) {
+                usb_settoggle(urb->dev, usb_pipeendpoint(urb->pipe),
+                                usb_pipeout(urb->pipe), qh->initial_toggle);
+                qh->needs_fixup = 0;
+        }
+
+        uhci_dec_fsbr(uhci, urb);       /* Safe since it checks */
+        uhci_free_urb_priv(uhci, urbp);
 
         switch (usb_pipetype(urb->pipe)) {
         case PIPE_ISOCHRONOUS:
@@ -1277,122 +1245,107 @@ static void uhci_transfer_result(struct uhci_hcd *uhci, struct urb *urb)
         case PIPE_INTERRUPT:
                 /* Release bandwidth for Interrupt or Isoc. transfers */
                 /* Make sure we don't release if we have a queued URB */
-                if (list_empty(&urbp->qh->queue) && urb->bandwidth)
+                if (list_empty(&qh->queue) && urb->bandwidth)
                         usb_release_bandwidth(urb->dev, urb, 0);
                 else
                         /* bandwidth was passed on to queued URB, */
                         /* so don't let usb_unlink_urb() release it */
                         urb->bandwidth = 0;
-                /* Falls through */
-        case PIPE_BULK:
-                if (status < 0)
-                        uhci_fixup_toggles(urb);
-                break;
-        default:        /* PIPE_CONTROL */
                 break;
         }
 
-        /* Take the URB's TDs off the hardware schedule */
-        uhci_remove_tds_from_schedule(uhci, urb, status);
-
-        /* Take the URB off the QH's queue and see if the QH is now unused */
-        list_del_init(&urbp->node);
-        if (list_empty(&urbp->qh->queue))
-                uhci_unlink_qh(uhci, urbp->qh);
+        spin_unlock(&uhci->lock);
+        usb_hcd_giveback_urb(uhci_to_hcd(uhci), urb, regs);
+        spin_lock(&uhci->lock);
 
-        uhci_dec_fsbr(uhci, urb);       /* Safe since it checks */
+        /* If the queue is now empty, we can unlink the QH and give up its
+         * reserved bandwidth. */
+        if (list_empty(&qh->queue)) {
+                uhci_unlink_qh(uhci, qh);
 
-        /* Queue it for giving back */
-        list_move_tail(&urbp->urb_list, &uhci->complete_list);
+                /* Bandwidth stuff not yet implemented */
+        }
 }
 
 /*
- * Check out the QHs waiting to be fully unlinked
+ * Scan the URBs in a QH's queue
  */
-static void uhci_scan_unlinking_qhs(struct uhci_hcd *uhci)
-{
-        struct uhci_qh *qh, *tmp;
+#define QH_FINISHED_UNLINKING(qh)                       \
+                (qh->state == QH_STATE_UNLINKING &&     \
+                uhci->frame_number + uhci->is_stopped != qh->unlink_frame)
 
-        list_for_each_entry_safe(qh, tmp, &uhci->skel_unlink_qh->node, node) {
-
-                /* If the queue is empty and the QH is fully unlinked then
-                 * it can become IDLE. */
-                if (list_empty(&qh->queue)) {
-                        if (uhci->frame_number + uhci->is_stopped !=
-                                        qh->unlink_frame)
-                                uhci_make_qh_idle(uhci, qh);
-
-                /* If none of the QH's URBs have been dequeued then the QH
-                 * should be re-activated. */
-                } else {
-                        struct urb_priv *urbp;
-                        int any_dequeued = 0;
-
-                        list_for_each_entry(urbp, &qh->queue, node) {
-                                if (urbp->urb->status != -EINPROGRESS) {
-                                        any_dequeued = 1;
-                                        break;
-                                }
-                        }
-                        if (!any_dequeued)
-                                uhci_activate_qh(uhci, qh);
-                }
-        }
-}
-
-static int uhci_urb_dequeue(struct usb_hcd *hcd, struct urb *urb)
+static void uhci_scan_qh(struct uhci_hcd *uhci, struct uhci_qh *qh,
+                struct pt_regs *regs)
 {
-        struct uhci_hcd *uhci = hcd_to_uhci(hcd);
-        unsigned long flags;
         struct urb_priv *urbp;
+        struct urb *urb;
+        int status;
 
-        spin_lock_irqsave(&uhci->lock, flags);
-        urbp = urb->hcpriv;
-        if (!urbp)                      /* URB was never linked! */
-                goto done;
+        while (!list_empty(&qh->queue)) {
+                urbp = list_entry(qh->queue.next, struct urb_priv, node);
+                urb = urbp->urb;
 
-        /* Remove Isochronous TDs from the frame list ASAP */
-        if (usb_pipetype(urb->pipe) == PIPE_ISOCHRONOUS)
-                uhci_unlink_isochronous_tds(uhci, urb);
-        uhci_unlink_qh(uhci, urbp->qh);
+                switch (usb_pipetype(urb->pipe)) {
+                case PIPE_CONTROL:
+                        status = uhci_result_control(uhci, urb);
+                        break;
+                case PIPE_ISOCHRONOUS:
+                        status = uhci_result_isochronous(uhci, urb);
+                        break;
+                default:        /* PIPE_BULK or PIPE_INTERRUPT */
+                        status = uhci_result_common(uhci, urb);
+                        break;
+                }
+                if (status == -EINPROGRESS)
+                        break;
 
-done:
-        spin_unlock_irqrestore(&uhci->lock, flags);
-        return 0;
-}
+                spin_lock(&urb->lock);
+                if (urb->status == -EINPROGRESS)        /* Not dequeued */
+                        urb->status = status;
+                else
+                        status = -ECONNRESET;
+                spin_unlock(&urb->lock);
 
-static int uhci_fsbr_timeout(struct uhci_hcd *uhci, struct urb *urb)
-{
-        struct urb_priv *urbp = (struct urb_priv *)urb->hcpriv;
-        struct list_head *head;
-        struct uhci_td *td;
-        int count = 0;
+                /* Dequeued but completed URBs can't be given back unless
+                 * the QH is stopped or has finished unlinking. */
+                if (status == -ECONNRESET &&
+                                !(qh->is_stopped || QH_FINISHED_UNLINKING(qh)))
+                        return;
 
-        uhci_dec_fsbr(uhci, urb);
+                uhci_giveback_urb(uhci, qh, urb, regs);
+                if (qh->is_stopped)
+                        break;
+        }
 
-        urbp->fsbr_timeout = 1;
+        /* If the QH is neither stopped nor finished unlinking (normal case),
+         * our work here is done. */
+ restart:
+        if (!(qh->is_stopped || QH_FINISHED_UNLINKING(qh)))
+                return;
 
-        /*
-         * Ideally we would want to fix qh->element as well, but it's
-         * read/write by the HC, so that can introduce a race. It's not
-         * really worth the hassle
-         */
+        /* Otherwise give back each of the dequeued URBs */
+        list_for_each_entry(urbp, &qh->queue, node) {
+                urb = urbp->urb;
+                if (urb->status != -EINPROGRESS) {
+                        uhci_save_toggle(qh, urb);
+                        uhci_giveback_urb(uhci, qh, urb, regs);
+                        goto restart;
+                }
+        }
+        qh->is_stopped = 0;
 
-        head = &urbp->td_list;
-        list_for_each_entry(td, head, list) {
-                /*
-                 * Make sure we don't do the last one (since it'll have the
-                 * TERM bit set) as well as we skip every so many TDs to
-                 * make sure it doesn't hog the bandwidth
-                 */
-                if (td->list.next != head && (count % DEPTH_INTERVAL) ==
-                                (DEPTH_INTERVAL - 1))
-                        td->link |= UHCI_PTR_DEPTH;
-
-                count++;
+        /* There are no more dequeued URBs.  If there are still URBs on the
+         * queue, the QH can now be re-activated. */
+        if (!list_empty(&qh->queue)) {
+                if (qh->needs_fixup)
+                        uhci_fixup_toggles(qh, 0);
+                uhci_activate_qh(uhci, qh);
         }
 
-        return 0;
+        /* The queue is empty.  The QH can become idle if it is fully
+         * unlinked. */
+        else if (QH_FINISHED_UNLINKING(qh))
+                uhci_make_qh_idle(uhci, qh);
 }
 
 static void uhci_free_pending_tds(struct uhci_hcd *uhci)
@@ -1406,36 +1359,13 @@ static void uhci_free_pending_tds(struct uhci_hcd *uhci)
         }
 }
 
-static void
-uhci_finish_urb(struct usb_hcd *hcd, struct urb *urb, struct pt_regs *regs)
-__releases(uhci->lock)
-__acquires(uhci->lock)
-{
-        struct uhci_hcd *uhci = hcd_to_uhci(hcd);
-
-        uhci_free_urb_priv(uhci, (struct urb_priv *) (urb->hcpriv));
-
-        spin_unlock(&uhci->lock);
-        usb_hcd_giveback_urb(hcd, urb, regs);
-        spin_lock(&uhci->lock);
-}
-
-static void uhci_finish_completion(struct uhci_hcd *uhci, struct pt_regs *regs)
-{
-        struct urb_priv *urbp, *tmp;
-
-        list_for_each_entry_safe(urbp, tmp, &uhci->complete_list, urb_list) {
-                struct urb *urb = urbp->urb;
-
-                list_del_init(&urbp->urb_list);
-                uhci_finish_urb(uhci_to_hcd(uhci), urb, regs);
-        }
-}
-
-/* Process events in the schedule, but only in one thread at a time */
+/*
+ * Process events in the schedule, but only in one thread at a time
+ */
 static void uhci_scan_schedule(struct uhci_hcd *uhci, struct pt_regs *regs)
 {
-        struct urb_priv *urbp, *tmp;
+        int i;
+        struct uhci_qh *qh;
 
         /* Don't allow re-entrant calls */
         if (uhci->scan_in_progress) {
@@ -1452,26 +1382,24 @@ static void uhci_scan_schedule(struct uhci_hcd *uhci, struct pt_regs *regs)
         if (uhci->frame_number + uhci->is_stopped != uhci->td_remove_age)
                 uhci_free_pending_tds(uhci);
 
-        /* Walk the list of pending URBs to see which ones completed
-         * (must be _safe because uhci_transfer_result() dequeues URBs) */
-        list_for_each_entry_safe(urbp, tmp, &uhci->urb_list, urb_list) {
-                struct urb *urb = urbp->urb;
-
-                /* Checks the status and does all of the magic necessary */
-                uhci_transfer_result(uhci, urb);
+        /* Go through all the QH queues and process the URBs in each one */
+        for (i = 0; i < UHCI_NUM_SKELQH - 1; ++i) {
+                uhci->next_qh = list_entry(uhci->skelqh[i]->node.next,
+                                struct uhci_qh, node);
+                while ((qh = uhci->next_qh) != uhci->skelqh[i]) {
+                        uhci->next_qh = list_entry(qh->node.next,
+                                        struct uhci_qh, node);
+                        uhci_scan_qh(uhci, qh, regs);
+                }
         }
-        uhci_finish_completion(uhci, regs);
-
-        /* If the controller is stopped, we can finish these off right now */
-        if (uhci->is_stopped)
-                uhci_free_pending_tds(uhci);
 
         if (uhci->need_rescan)
                 goto rescan;
         uhci->scan_in_progress = 0;
 
-        /* Check out the QHs waiting for unlinking */
-        uhci_scan_unlinking_qhs(uhci);
+        /* If the controller is stopped, we can finish these off right now */
+        if (uhci->is_stopped)
+                uhci_free_pending_tds(uhci);
 
         if (list_empty(&uhci->td_remove_list) &&
                         list_empty(&uhci->skel_unlink_qh->node))
@@ -1482,19 +1410,8 @@ static void uhci_scan_schedule(struct uhci_hcd *uhci, struct pt_regs *regs)
 
 static void check_fsbr(struct uhci_hcd *uhci)
 {
-        struct urb_priv *up;
-
-        list_for_each_entry(up, &uhci->urb_list, urb_list) {
-                struct urb *u = up->urb;
-
-                spin_lock(&u->lock);
-
-                /* Check if the FSBR timed out */
-                if (up->fsbr && !up->fsbr_timeout && time_after_eq(jiffies, up->fsbrtime + IDLE_TIMEOUT))
-                        uhci_fsbr_timeout(uhci, u);
-
-                spin_unlock(&u->lock);
-        }
+        /* For now, don't scan URBs for FSBR timeouts.
+         * Add it back in later... */
 
         /* Really disable FSBR */
         if (!uhci->fsbr && uhci->fsbrtimeout && time_after_eq(jiffies, uhci->fsbrtimeout)) {