USB: UHCI: improve scheduling of interrupt URBs

[deliverable/linux.git] / drivers / usb / host / uhci-q.c

/*
 * Universal Host Controller Interface driver for USB.
 *
 * Maintainer: Alan Stern <stern@rowland.harvard.edu>
 *
 * (C) Copyright 1999 Linus Torvalds
 * (C) Copyright 1999-2002 Johannes Erdfelt, johannes@erdfelt.com
 * (C) Copyright 1999 Randy Dunlap
 * (C) Copyright 1999 Georg Acher, acher@in.tum.de
 * (C) Copyright 1999 Deti Fliegl, deti@fliegl.de
 * (C) Copyright 1999 Thomas Sailer, sailer@ife.ee.ethz.ch
 * (C) Copyright 1999 Roman Weissgaerber, weissg@vienna.at
 * (C) Copyright 2000 Yggdrasil Computing, Inc. (port of new PCI interface
 *               support from usb-ohci.c by Adam Richter, adam@yggdrasil.com).
 * (C) Copyright 1999 Gregory P. Smith (from usb-ohci.c)
 * (C) Copyright 2004-2007 Alan Stern, stern@rowland.harvard.edu
 */


/*
 * Technically, updating td->status here is a race, but it's not really a
 * problem. The worst that can happen is that we set the IOC bit again
 * generating a spurious interrupt. We could fix this by creating another
 * QH and leaving the IOC bit always set, but then we would have to play
 * games with the FSBR code to make sure we get the correct order in all
 * the cases. I don't think it's worth the effort
 */
static void uhci_set_next_interrupt(struct uhci_hcd *uhci)
{
        if (uhci->is_stopped)
                mod_timer(&uhci_to_hcd(uhci)->rh_timer, jiffies);
        uhci->term_td->status |= cpu_to_le32(TD_CTRL_IOC); 
}

static inline void uhci_clear_next_interrupt(struct uhci_hcd *uhci)
{
        uhci->term_td->status &= ~cpu_to_le32(TD_CTRL_IOC);
}


/*
 * Full-Speed Bandwidth Reclamation (FSBR).
 * We turn on FSBR whenever a queue that wants it is advancing,
 * and leave it on for a short time thereafter.
 */
static void uhci_fsbr_on(struct uhci_hcd *uhci)
{
        struct uhci_qh *lqh;

        /* The terminating skeleton QH always points back to the first
         * FSBR QH.  Make the last async QH point to the terminating
         * skeleton QH. */
        uhci->fsbr_is_on = 1;
        lqh = list_entry(uhci->skel_async_qh->node.prev,
                        struct uhci_qh, node);
        lqh->link = LINK_TO_QH(uhci->skel_term_qh);
}

static void uhci_fsbr_off(struct uhci_hcd *uhci)
{
        struct uhci_qh *lqh;

        /* Remove the link from the last async QH to the terminating
         * skeleton QH. */
        uhci->fsbr_is_on = 0;
        lqh = list_entry(uhci->skel_async_qh->node.prev,
                        struct uhci_qh, node);
        lqh->link = UHCI_PTR_TERM;
}

static void uhci_add_fsbr(struct uhci_hcd *uhci, struct urb *urb)
{
        struct urb_priv *urbp = urb->hcpriv;

        if (!(urb->transfer_flags & URB_NO_FSBR))
                urbp->fsbr = 1;
}

static void uhci_urbp_wants_fsbr(struct uhci_hcd *uhci, struct urb_priv *urbp)
{
        if (urbp->fsbr) {
                uhci->fsbr_is_wanted = 1;
                if (!uhci->fsbr_is_on)
                        uhci_fsbr_on(uhci);
                else if (uhci->fsbr_expiring) {
                        uhci->fsbr_expiring = 0;
                        del_timer(&uhci->fsbr_timer);
                }
        }
}

static void uhci_fsbr_timeout(unsigned long _uhci)
{
        struct uhci_hcd *uhci = (struct uhci_hcd *) _uhci;
        unsigned long flags;

        spin_lock_irqsave(&uhci->lock, flags);
        if (uhci->fsbr_expiring) {
                uhci->fsbr_expiring = 0;
                uhci_fsbr_off(uhci);
        }
        spin_unlock_irqrestore(&uhci->lock, flags);
}


static struct uhci_td *uhci_alloc_td(struct uhci_hcd *uhci)
{
        dma_addr_t dma_handle;
        struct uhci_td *td;

        td = dma_pool_alloc(uhci->td_pool, GFP_ATOMIC, &dma_handle);
        if (!td)
                return NULL;

        td->dma_handle = dma_handle;
        td->frame = -1;

        INIT_LIST_HEAD(&td->list);
        INIT_LIST_HEAD(&td->fl_list);

        return td;
}

static void uhci_free_td(struct uhci_hcd *uhci, struct uhci_td *td)
{
        if (!list_empty(&td->list))
                dev_WARN(uhci_dev(uhci), "td %p still in list!\n", td);
        if (!list_empty(&td->fl_list))
                dev_WARN(uhci_dev(uhci), "td %p still in fl_list!\n", td);

        dma_pool_free(uhci->td_pool, td, td->dma_handle);
}

static inline void uhci_fill_td(struct uhci_td *td, u32 status,
                u32 token, u32 buffer)
{
        td->status = cpu_to_le32(status);
        td->token = cpu_to_le32(token);
        td->buffer = cpu_to_le32(buffer);
}

static void uhci_add_td_to_urbp(struct uhci_td *td, struct urb_priv *urbp)
{
        list_add_tail(&td->list, &urbp->td_list);
}

static void uhci_remove_td_from_urbp(struct uhci_td *td)
{
        list_del_init(&td->list);
}

/*
 * We insert Isochronous URBs directly into the frame list at the beginning
 */
static inline void uhci_insert_td_in_frame_list(struct uhci_hcd *uhci,
                struct uhci_td *td, unsigned framenum)
{
        framenum &= (UHCI_NUMFRAMES - 1);

        td->frame = framenum;

        /* Is there a TD already mapped there? */
        if (uhci->frame_cpu[framenum]) {
                struct uhci_td *ftd, *ltd;

                ftd = uhci->frame_cpu[framenum];
                ltd = list_entry(ftd->fl_list.prev, struct uhci_td, fl_list);

                list_add_tail(&td->fl_list, &ftd->fl_list);

                td->link = ltd->link;
                wmb();
                ltd->link = LINK_TO_TD(td);
        } else {
                td->link = uhci->frame[framenum];
                wmb();
                uhci->frame[framenum] = LINK_TO_TD(td);
                uhci->frame_cpu[framenum] = td;
        }
}

static inline void uhci_remove_td_from_frame_list(struct uhci_hcd *uhci,
                struct uhci_td *td)
{
        /* If it's not inserted, don't remove it */
        if (td->frame == -1) {
                WARN_ON(!list_empty(&td->fl_list));
                return;
        }

        if (uhci->frame_cpu[td->frame] == td) {
                if (list_empty(&td->fl_list)) {
                        uhci->frame[td->frame] = td->link;
                        uhci->frame_cpu[td->frame] = NULL;
                } else {
                        struct uhci_td *ntd;

                        ntd = list_entry(td->fl_list.next, struct uhci_td, fl_list);
                        uhci->frame[td->frame] = LINK_TO_TD(ntd);
                        uhci->frame_cpu[td->frame] = ntd;
                }
        } else {
                struct uhci_td *ptd;

                ptd = list_entry(td->fl_list.prev, struct uhci_td, fl_list);
                ptd->link = td->link;
        }

        list_del_init(&td->fl_list);
        td->frame = -1;
}

static inline void uhci_remove_tds_from_frame(struct uhci_hcd *uhci,
                unsigned int framenum)
{
        struct uhci_td *ftd, *ltd;

        framenum &= (UHCI_NUMFRAMES - 1);

        ftd = uhci->frame_cpu[framenum];
        if (ftd) {
                ltd = list_entry(ftd->fl_list.prev, struct uhci_td, fl_list);
                uhci->frame[framenum] = ltd->link;
                uhci->frame_cpu[framenum] = NULL;

                while (!list_empty(&ftd->fl_list))
                        list_del_init(ftd->fl_list.prev);
        }
}

/*
 * Remove all the TDs for an Isochronous URB from the frame list
 */
static void uhci_unlink_isochronous_tds(struct uhci_hcd *uhci, struct urb *urb)
{
        struct urb_priv *urbp = (struct urb_priv *) urb->hcpriv;
        struct uhci_td *td;

        list_for_each_entry(td, &urbp->td_list, list)
                uhci_remove_td_from_frame_list(uhci, td);
}

static struct uhci_qh *uhci_alloc_qh(struct uhci_hcd *uhci,
                struct usb_device *udev, struct usb_host_endpoint *hep)
{
        dma_addr_t dma_handle;
        struct uhci_qh *qh;

        qh = dma_pool_alloc(uhci->qh_pool, GFP_ATOMIC, &dma_handle);
        if (!qh)
                return NULL;

        memset(qh, 0, sizeof(*qh));
        qh->dma_handle = dma_handle;

        qh->element = UHCI_PTR_TERM;
        qh->link = UHCI_PTR_TERM;

        INIT_LIST_HEAD(&qh->queue);
        INIT_LIST_HEAD(&qh->node);

        if (udev) {             /* Normal QH */
                qh->type = hep->desc.bmAttributes & USB_ENDPOINT_XFERTYPE_MASK;
                if (qh->type != USB_ENDPOINT_XFER_ISOC) {
                        qh->dummy_td = uhci_alloc_td(uhci);
                        if (!qh->dummy_td) {
                                dma_pool_free(uhci->qh_pool, qh, dma_handle);
                                return NULL;
                        }
                }
                qh->state = QH_STATE_IDLE;
                qh->hep = hep;
                qh->udev = udev;
                hep->hcpriv = qh;

                if (qh->type == USB_ENDPOINT_XFER_INT ||
                                qh->type == USB_ENDPOINT_XFER_ISOC)
                        qh->load = usb_calc_bus_time(udev->speed,
                                        usb_endpoint_dir_in(&hep->desc),
                                        qh->type == USB_ENDPOINT_XFER_ISOC,
                                        le16_to_cpu(hep->desc.wMaxPacketSize))
                                / 1000 + 1;

        } else {                /* Skeleton QH */
                qh->state = QH_STATE_ACTIVE;
                qh->type = -1;
        }
        return qh;
}

static void uhci_free_qh(struct uhci_hcd *uhci, struct uhci_qh *qh)
{
        WARN_ON(qh->state != QH_STATE_IDLE && qh->udev);
        if (!list_empty(&qh->queue))
                dev_WARN(uhci_dev(uhci), "qh %p list not empty!\n", qh);

        list_del(&qh->node);
        if (qh->udev) {
                qh->hep->hcpriv = NULL;
                if (qh->dummy_td)
                        uhci_free_td(uhci, qh->dummy_td);
        }
        dma_pool_free(uhci->qh_pool, qh, qh->dma_handle);
}

/*
 * When a queue is stopped and a dequeued URB is given back, adjust
 * the previous TD link (if the URB isn't first on the queue) or
 * save its toggle value (if it is first and is currently executing).
 *
 * Returns 0 if the URB should not yet be given back, 1 otherwise.
 */
static int uhci_cleanup_queue(struct uhci_hcd *uhci, struct uhci_qh *qh,
                struct urb *urb)
{
        struct urb_priv *urbp = urb->hcpriv;
        struct uhci_td *td;
        int ret = 1;

        /* Isochronous pipes don't use toggles and their TD link pointers
         * get adjusted during uhci_urb_dequeue().  But since their queues
         * cannot truly be stopped, we have to watch out for dequeues
         * occurring after the nominal unlink frame. */
        if (qh->type == USB_ENDPOINT_XFER_ISOC) {
                ret = (uhci->frame_number + uhci->is_stopped !=
                                qh->unlink_frame);
                goto done;
        }

        /* If the URB isn't first on its queue, adjust the link pointer
         * of the last TD in the previous URB.  The toggle doesn't need
         * to be saved since this URB can't be executing yet. */
        if (qh->queue.next != &urbp->node) {
                struct urb_priv *purbp;
                struct uhci_td *ptd;

                purbp = list_entry(urbp->node.prev, struct urb_priv, node);
                WARN_ON(list_empty(&purbp->td_list));
                ptd = list_entry(purbp->td_list.prev, struct uhci_td,
                                list);
                td = list_entry(urbp->td_list.prev, struct uhci_td,
                                list);
                ptd->link = td->link;
                goto done;
        }

        /* 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)
                goto done;
        qh->element = UHCI_PTR_TERM;

        /* Control pipes don't have to worry about toggles */
        if (qh->type == USB_ENDPOINT_XFER_CONTROL)
                goto done;

        /* Save the next toggle value */
        WARN_ON(list_empty(&urbp->td_list));
        td = list_entry(urbp->td_list.next, struct uhci_td, list);
        qh->needs_fixup = 1;
        qh->initial_toggle = uhci_toggle(td_token(td));

done:
        return ret;
}

/*
 * 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. */
        urbp = 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.prev, 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;
}

/*
 * Link an Isochronous QH into its skeleton's list
 */
static inline void link_iso(struct uhci_hcd *uhci, struct uhci_qh *qh)
{
        list_add_tail(&qh->node, &uhci->skel_iso_qh->node);

        /* Isochronous QHs aren't linked by the hardware */
}

/*
 * Link a high-period interrupt QH into the schedule at the end of its
 * skeleton's list
 */
static void link_interrupt(struct uhci_hcd *uhci, struct uhci_qh *qh)
{
        struct uhci_qh *pqh;

        list_add_tail(&qh->node, &uhci->skelqh[qh->skel]->node);

        pqh = list_entry(qh->node.prev, struct uhci_qh, node);
        qh->link = pqh->link;
        wmb();
        pqh->link = LINK_TO_QH(qh);
}

/*
 * Link a period-1 interrupt or async QH into the schedule at the
 * correct spot in the async skeleton's list, and update the FSBR link
 */
static void link_async(struct uhci_hcd *uhci, struct uhci_qh *qh)
{
        struct uhci_qh *pqh;
        __le32 link_to_new_qh;

        /* Find the predecessor QH for our new one and insert it in the list.
         * The list of QHs is expected to be short, so linear search won't
         * take too long. */
        list_for_each_entry_reverse(pqh, &uhci->skel_async_qh->node, node) {
                if (pqh->skel <= qh->skel)
                        break;
        }
        list_add(&qh->node, &pqh->node);

        /* Link it into the schedule */
        qh->link = pqh->link;
        wmb();
        link_to_new_qh = LINK_TO_QH(qh);
        pqh->link = link_to_new_qh;

        /* If this is now the first FSBR QH, link the terminating skeleton
         * QH to it. */
        if (pqh->skel < SKEL_FSBR && qh->skel >= SKEL_FSBR)
                uhci->skel_term_qh->link = link_to_new_qh;
}

/*
 * Put a QH on the schedule in both hardware and software
 */
static void uhci_activate_qh(struct uhci_hcd *uhci, struct uhci_qh *qh)
{
        WARN_ON(list_empty(&qh->queue));

        /* Set the element pointer if it isn't set already.
         * This isn't needed for Isochronous queues, but it doesn't hurt. */
        if (qh_element(qh) == UHCI_PTR_TERM) {
                struct urb_priv *urbp = list_entry(qh->queue.next,
                                struct urb_priv, node);
                struct uhci_td *td = list_entry(urbp->td_list.next,
                                struct uhci_td, list);

                qh->element = LINK_TO_TD(td);
        }

        /* Treat the queue as if it has just advanced */
        qh->wait_expired = 0;
        qh->advance_jiffies = jiffies;

        if (qh->state == QH_STATE_ACTIVE)
                return;
        qh->state = QH_STATE_ACTIVE;

        /* Move the QH from its old list to the correct spot in the appropriate
         * skeleton's list */
        if (qh == uhci->next_qh)
                uhci->next_qh = list_entry(qh->node.next, struct uhci_qh,
                                node);
        list_del(&qh->node);

        if (qh->skel == SKEL_ISO)
                link_iso(uhci, qh);
        else if (qh->skel < SKEL_ASYNC)
                link_interrupt(uhci, qh);
        else
                link_async(uhci, qh);
}

/*
 * Unlink a high-period interrupt QH from the schedule
 */
static void unlink_interrupt(struct uhci_hcd *uhci, struct uhci_qh *qh)
{
        struct uhci_qh *pqh;

        pqh = list_entry(qh->node.prev, struct uhci_qh, node);
        pqh->link = qh->link;
        mb();
}

/*
 * Unlink a period-1 interrupt or async QH from the schedule
 */
static void unlink_async(struct uhci_hcd *uhci, struct uhci_qh *qh)
{
        struct uhci_qh *pqh;
        __le32 link_to_next_qh = qh->link;

        pqh = list_entry(qh->node.prev, struct uhci_qh, node);
        pqh->link = link_to_next_qh;

        /* If this was the old first FSBR QH, link the terminating skeleton
         * QH to the next (new first FSBR) QH. */
        if (pqh->skel < SKEL_FSBR && qh->skel >= SKEL_FSBR)
                uhci->skel_term_qh->link = link_to_next_qh;
        mb();
}

/*
 * Take a QH off the hardware schedule
 */
static void uhci_unlink_qh(struct uhci_hcd *uhci, struct uhci_qh *qh)
{
        if (qh->state == QH_STATE_UNLINKING)
                return;
        WARN_ON(qh->state != QH_STATE_ACTIVE || !qh->udev);
        qh->state = QH_STATE_UNLINKING;

        /* Unlink the QH from the schedule and record when we did it */
        if (qh->skel == SKEL_ISO)
                ;
        else if (qh->skel < SKEL_ASYNC)
                unlink_interrupt(uhci, qh);
        else
                unlink_async(uhci, qh);

        uhci_get_current_frame_number(uhci);
        qh->unlink_frame = uhci->frame_number;

        /* Force an interrupt so we know when the QH is fully unlinked */
        if (list_empty(&uhci->skel_unlink_qh->node))
                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);
}

/*
 * When we and the controller are through with a QH, it becomes IDLE.
 * This happens when a QH has been off the schedule (on the unlinking
 * list) for more than one frame, or when an error occurs while adding
 * the first URB onto a new QH.
 */
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;

        /* Now that the QH is idle, its post_td isn't being used */
        if (qh->post_td) {
                uhci_free_td(uhci, qh->post_td);
                qh->post_td = NULL;
        }

        /* If anyone is waiting for a QH to become idle, wake them up */
        if (uhci->num_waiting)
                wake_up_all(&uhci->waitqh);
}

/*
 * Find the highest existing bandwidth load for a given phase and period.
 */
static int uhci_highest_load(struct uhci_hcd *uhci, int phase, int period)
{
        int highest_load = uhci->load[phase];

        for (phase += period; phase < MAX_PHASE; phase += period)
                highest_load = max_t(int, highest_load, uhci->load[phase]);
        return highest_load;
}

/*
 * Set qh->phase to the optimal phase for a periodic transfer and
 * check whether the bandwidth requirement is acceptable.
 */
static int uhci_check_bandwidth(struct uhci_hcd *uhci, struct uhci_qh *qh)
{
        int minimax_load;

        /* Find the optimal phase (unless it is already set) and get
         * its load value. */
        if (qh->phase >= 0)
                minimax_load = uhci_highest_load(uhci, qh->phase, qh->period);
        else {
                int phase, load;
                int max_phase = min_t(int, MAX_PHASE, qh->period);

                qh->phase = 0;
                minimax_load = uhci_highest_load(uhci, qh->phase, qh->period);
                for (phase = 1; phase < max_phase; ++phase) {
                        load = uhci_highest_load(uhci, phase, qh->period);
                        if (load < minimax_load) {
                                minimax_load = load;
                                qh->phase = phase;
                        }
                }
        }

        /* Maximum allowable periodic bandwidth is 90%, or 900 us per frame */
        if (minimax_load + qh->load > 900) {
                dev_dbg(uhci_dev(uhci), "bandwidth allocation failed: "
                                "period %d, phase %d, %d + %d us\n",
                                qh->period, qh->phase, minimax_load, qh->load);
                return -ENOSPC;
        }
        return 0;
}

/*
 * Reserve a periodic QH's bandwidth in the schedule
 */
static void uhci_reserve_bandwidth(struct uhci_hcd *uhci, struct uhci_qh *qh)
{
        int i;
        int load = qh->load;
        char *p = "??";

        for (i = qh->phase; i < MAX_PHASE; i += qh->period) {
                uhci->load[i] += load;
                uhci->total_load += load;
        }
        uhci_to_hcd(uhci)->self.bandwidth_allocated =
                        uhci->total_load / MAX_PHASE;
        switch (qh->type) {
        case USB_ENDPOINT_XFER_INT:
                ++uhci_to_hcd(uhci)->self.bandwidth_int_reqs;
                p = "INT";
                break;
        case USB_ENDPOINT_XFER_ISOC:
                ++uhci_to_hcd(uhci)->self.bandwidth_isoc_reqs;
                p = "ISO";
                break;
        }
        qh->bandwidth_reserved = 1;
        dev_dbg(uhci_dev(uhci),
                        "%s dev %d ep%02x-%s, period %d, phase %d, %d us\n",
                        "reserve", qh->udev->devnum,
                        qh->hep->desc.bEndpointAddress, p,
                        qh->period, qh->phase, load);
}

/*
 * Release a periodic QH's bandwidth reservation
 */
static void uhci_release_bandwidth(struct uhci_hcd *uhci, struct uhci_qh *qh)
{
        int i;
        int load = qh->load;
        char *p = "??";

        for (i = qh->phase; i < MAX_PHASE; i += qh->period) {
                uhci->load[i] -= load;
                uhci->total_load -= load;
        }
        uhci_to_hcd(uhci)->self.bandwidth_allocated =
                        uhci->total_load / MAX_PHASE;
        switch (qh->type) {
        case USB_ENDPOINT_XFER_INT:
                --uhci_to_hcd(uhci)->self.bandwidth_int_reqs;
                p = "INT";
                break;
        case USB_ENDPOINT_XFER_ISOC:
                --uhci_to_hcd(uhci)->self.bandwidth_isoc_reqs;
                p = "ISO";
                break;
        }
        qh->bandwidth_reserved = 0;
        dev_dbg(uhci_dev(uhci),
                        "%s dev %d ep%02x-%s, period %d, phase %d, %d us\n",
                        "release", qh->udev->devnum,
                        qh->hep->desc.bEndpointAddress, p,
                        qh->period, qh->phase, load);
}

static inline struct urb_priv *uhci_alloc_urb_priv(struct uhci_hcd *uhci,
                struct urb *urb)
{
        struct urb_priv *urbp;

        urbp = kmem_cache_zalloc(uhci_up_cachep, GFP_ATOMIC);
        if (!urbp)
                return NULL;

        urbp->urb = urb;
        urb->hcpriv = urbp;
        
        INIT_LIST_HEAD(&urbp->node);
        INIT_LIST_HEAD(&urbp->td_list);

        return urbp;
}

static void uhci_free_urb_priv(struct uhci_hcd *uhci,
                struct urb_priv *urbp)
{
        struct uhci_td *td, *tmp;

        if (!list_empty(&urbp->node))
                dev_WARN(uhci_dev(uhci), "urb %p still on QH's list!\n",
                                urbp->urb);

        list_for_each_entry_safe(td, tmp, &urbp->td_list, list) {
                uhci_remove_td_from_urbp(td);
                uhci_free_td(uhci, td);
        }

        kmem_cache_free(uhci_up_cachep, urbp);
}

/*
 * Map status to standard result codes
 *
 * <status> is (td_status(td) & 0xF60000), a.k.a.
 * uhci_status_bits(td_status(td)).
 * Note: <status> does not include the TD_CTRL_NAK bit.
 * <dir_out> is True for output TDs and False for input TDs.
 */
static int uhci_map_status(int status, int dir_out)
{
        if (!status)
                return 0;
        if (status & TD_CTRL_BITSTUFF)                  /* Bitstuff error */
                return -EPROTO;
        if (status & TD_CTRL_CRCTIMEO) {                /* CRC/Timeout */
                if (dir_out)
                        return -EPROTO;
                else
                        return -EILSEQ;
        }
        if (status & TD_CTRL_BABBLE)                    /* Babble */
                return -EOVERFLOW;
        if (status & TD_CTRL_DBUFERR)                   /* Buffer error */
                return -ENOSR;
        if (status & TD_CTRL_STALLED)                   /* Stalled */
                return -EPIPE;
        return 0;
}

/*
 * Control transfers
 */
static int uhci_submit_control(struct uhci_hcd *uhci, struct urb *urb,
                struct uhci_qh *qh)
{
        struct uhci_td *td;
        unsigned long destination, status;
        int maxsze = le16_to_cpu(qh->hep->desc.wMaxPacketSize);
        int len = urb->transfer_buffer_length;
        dma_addr_t data = urb->transfer_dma;
        __le32 *plink;
        struct urb_priv *urbp = urb->hcpriv;
        int skel;

        /* The "pipe" thing contains the destination in bits 8--18 */
        destination = (urb->pipe & PIPE_DEVEP_MASK) | USB_PID_SETUP;

        /* 3 errors, dummy TD remains inactive */
        status = uhci_maxerr(3);
        if (urb->dev->speed == USB_SPEED_LOW)
                status |= TD_CTRL_LS;

        /*
         * Build the TD for the control request setup packet
         */
        td = qh->dummy_td;
        uhci_add_td_to_urbp(td, urbp);
        uhci_fill_td(td, status, destination | uhci_explen(8),
                        urb->setup_dma);
        plink = &td->link;
        status |= TD_CTRL_ACTIVE;

        /*
         * If direction is "send", change the packet ID from SETUP (0x2D)
         * to OUT (0xE1).  Else change it from SETUP to IN (0x69) and
         * set Short Packet Detect (SPD) for all data packets.
         *
         * 0-length transfers always get treated as "send".
         */
        if (usb_pipeout(urb->pipe) || len == 0)
                destination ^= (USB_PID_SETUP ^ USB_PID_OUT);
        else {
                destination ^= (USB_PID_SETUP ^ USB_PID_IN);
                status |= TD_CTRL_SPD;
        }

        /*
         * Build the DATA TDs
         */
        while (len > 0) {
                int pktsze = maxsze;

                if (len <= pktsze) {            /* The last data packet */
                        pktsze = len;
                        status &= ~TD_CTRL_SPD;
                }

                td = uhci_alloc_td(uhci);
                if (!td)
                        goto nomem;
                *plink = LINK_TO_TD(td);

                /* Alternate Data0/1 (start with Data1) */
                destination ^= TD_TOKEN_TOGGLE;
        
                uhci_add_td_to_urbp(td, urbp);
                uhci_fill_td(td, status, destination | uhci_explen(pktsze),
                                data);
                plink = &td->link;

                data += pktsze;
                len -= pktsze;
        }

        /*
         * Build the final TD for control status 
         */
        td = uhci_alloc_td(uhci);
        if (!td)
                goto nomem;
        *plink = LINK_TO_TD(td);

        /* Change direction for the status transaction */
        destination ^= (USB_PID_IN ^ USB_PID_OUT);
        destination |= TD_TOKEN_TOGGLE;         /* End in Data1 */

        uhci_add_td_to_urbp(td, urbp);
        uhci_fill_td(td, status | TD_CTRL_IOC,
                        destination | uhci_explen(0), 0);
        plink = &td->link;

        /*
         * Build the new dummy TD and activate the old one
         */
        td = uhci_alloc_td(uhci);
        if (!td)
                goto nomem;
        *plink = LINK_TO_TD(td);

        uhci_fill_td(td, 0, USB_PID_OUT | uhci_explen(0), 0);
        wmb();
        qh->dummy_td->status |= __constant_cpu_to_le32(TD_CTRL_ACTIVE);
        qh->dummy_td = td;

        /* Low-speed transfers get a different queue, and won't hog the bus.
         * Also, some devices enumerate better without FSBR; the easiest way
         * to do that is to put URBs on the low-speed queue while the device
         * isn't in the CONFIGURED state. */
        if (urb->dev->speed == USB_SPEED_LOW ||
                        urb->dev->state != USB_STATE_CONFIGURED)
                skel = SKEL_LS_CONTROL;
        else {
                skel = SKEL_FS_CONTROL;
                uhci_add_fsbr(uhci, urb);
        }
        if (qh->state != QH_STATE_ACTIVE)
                qh->skel = skel;

        urb->actual_length = -8;        /* Account for the SETUP packet */
        return 0;

nomem:
        /* Remove the dummy TD from the td_list so it doesn't get freed */
        uhci_remove_td_from_urbp(qh->dummy_td);
        return -ENOMEM;
}

/*
 * Common submit for bulk and interrupt
 */
static int uhci_submit_common(struct uhci_hcd *uhci, struct urb *urb,
                struct uhci_qh *qh)
{
        struct uhci_td *td;
        unsigned long destination, status;
        int maxsze = le16_to_cpu(qh->hep->desc.wMaxPacketSize);
        int len = urb->transfer_buffer_length;
        dma_addr_t data = urb->transfer_dma;
        __le32 *plink;
        struct urb_priv *urbp = urb->hcpriv;
        unsigned int toggle;

        if (len < 0)
                return -EINVAL;

        /* The "pipe" thing contains the destination in bits 8--18 */
        destination = (urb->pipe & PIPE_DEVEP_MASK) | usb_packetid(urb->pipe);
        toggle = usb_gettoggle(urb->dev, usb_pipeendpoint(urb->pipe),
                         usb_pipeout(urb->pipe));

        /* 3 errors, dummy TD remains inactive */
        status = uhci_maxerr(3);
        if (urb->dev->speed == USB_SPEED_LOW)
                status |= TD_CTRL_LS;
        if (usb_pipein(urb->pipe))
                status |= TD_CTRL_SPD;

        /*
         * Build the DATA TDs
         */
        plink = NULL;
        td = qh->dummy_td;
        do {    /* Allow zero length packets */
                int pktsze = maxsze;

                if (len <= pktsze) {            /* The last packet */
                        pktsze = len;
                        if (!(urb->transfer_flags & URB_SHORT_NOT_OK))
                                status &= ~TD_CTRL_SPD;
                }

                if (plink) {
                        td = uhci_alloc_td(uhci);
                        if (!td)
                                goto nomem;
                        *plink = LINK_TO_TD(td);
                }
                uhci_add_td_to_urbp(td, urbp);
                uhci_fill_td(td, status,
                                destination | uhci_explen(pktsze) |
                                        (toggle << TD_TOKEN_TOGGLE_SHIFT),
                                data);
                plink = &td->link;
                status |= TD_CTRL_ACTIVE;

                data += pktsze;
                len -= maxsze;
                toggle ^= 1;
        } while (len > 0);

        /*
         * URB_ZERO_PACKET means adding a 0-length packet, if direction
         * is OUT and the transfer_length was an exact multiple of maxsze,
         * hence (len = transfer_length - N * maxsze) == 0
         * however, if transfer_length == 0, the zero packet was already
         * prepared above.
         */
        if ((urb->transfer_flags & URB_ZERO_PACKET) &&
                        usb_pipeout(urb->pipe) && len == 0 &&
                        urb->transfer_buffer_length > 0) {
                td = uhci_alloc_td(uhci);
                if (!td)
                        goto nomem;
                *plink = LINK_TO_TD(td);

                uhci_add_td_to_urbp(td, urbp);
                uhci_fill_td(td, status,
                                destination | uhci_explen(0) |
                                        (toggle << TD_TOKEN_TOGGLE_SHIFT),
                                data);
                plink = &td->link;

                toggle ^= 1;
        }

        /* Set the interrupt-on-completion flag on the last packet.
         * A more-or-less typical 4 KB URB (= size of one memory page)
         * will require about 3 ms to transfer; that's a little on the
         * fast side but not enough to justify delaying an interrupt
         * more than 2 or 3 URBs, so we will ignore the URB_NO_INTERRUPT
         * flag setting. */
        td->status |= __constant_cpu_to_le32(TD_CTRL_IOC);

        /*
         * Build the new dummy TD and activate the old one
         */
        td = uhci_alloc_td(uhci);
        if (!td)
                goto nomem;
        *plink = LINK_TO_TD(td);

        uhci_fill_td(td, 0, USB_PID_OUT | uhci_explen(0), 0);
        wmb();
        qh->dummy_td->status |= __constant_cpu_to_le32(TD_CTRL_ACTIVE);
        qh->dummy_td = td;

        usb_settoggle(urb->dev, usb_pipeendpoint(urb->pipe),
                        usb_pipeout(urb->pipe), toggle);
        return 0;

nomem:
        /* Remove the dummy TD from the td_list so it doesn't get freed */
        uhci_remove_td_from_urbp(qh->dummy_td);
        return -ENOMEM;
}

static int uhci_submit_bulk(struct uhci_hcd *uhci, struct urb *urb,
                struct uhci_qh *qh)
{
        int ret;

        /* Can't have low-speed bulk transfers */
        if (urb->dev->speed == USB_SPEED_LOW)
                return -EINVAL;

        if (qh->state != QH_STATE_ACTIVE)
                qh->skel = SKEL_BULK;
        ret = uhci_submit_common(uhci, urb, qh);
        if (ret == 0)
                uhci_add_fsbr(uhci, urb);
        return ret;
}

static int uhci_submit_interrupt(struct uhci_hcd *uhci, struct urb *urb,
                struct uhci_qh *qh)
{
        int ret;

        /* USB 1.1 interrupt transfers only involve one packet per interval.
         * Drivers can submit URBs of any length, but longer ones will need
         * multiple intervals to complete.
         */

        if (!qh->bandwidth_reserved) {
                int exponent;

                /* Figure out which power-of-two queue to use */
                for (exponent = 7; exponent >= 0; --exponent) {
                        if ((1 << exponent) <= urb->interval)
                                break;
                }
                if (exponent < 0)
                        return -EINVAL;

                /* If the slot is full, try a lower period */
                do {
                        qh->period = 1 << exponent;
                        qh->skel = SKEL_INDEX(exponent);

                        /* For now, interrupt phase is fixed by the layout
                         * of the QH lists.
                         */
                        qh->phase = (qh->period / 2) & (MAX_PHASE - 1);
                        ret = uhci_check_bandwidth(uhci, qh);
                } while (ret != 0 && --exponent >= 0);
                if (ret)
                        return ret;
        } else if (qh->period > urb->interval)
                return -EINVAL;         /* Can't decrease the period */

        ret = uhci_submit_common(uhci, urb, qh);
        if (ret == 0) {
                urb->interval = qh->period;
                if (!qh->bandwidth_reserved)
                        uhci_reserve_bandwidth(uhci, qh);
        }
        return ret;
}

/*
 * Fix up the data structures following a short transfer
 */
static int uhci_fixup_short_transfer(struct uhci_hcd *uhci,
                struct uhci_qh *qh, struct urb_priv *urbp)
{
        struct uhci_td *td;
        struct list_head *tmp;
        int ret;

        td = list_entry(urbp->td_list.prev, struct uhci_td, list);
        if (qh->type == USB_ENDPOINT_XFER_CONTROL) {

                /* When a control transfer is short, we have to restart
                 * the queue at the status stage transaction, which is
                 * the last TD. */
                WARN_ON(list_empty(&urbp->td_list));
                qh->element = LINK_TO_TD(td);
                tmp = td->list.prev;
                ret = -EINPROGRESS;

        } else {

                /* When a bulk/interrupt transfer is short, we have to
                 * fix up the toggles of the following URBs on the queue
                 * before restarting the queue at the next URB. */
                qh->initial_toggle = uhci_toggle(td_token(qh->post_td)) ^ 1;
                uhci_fixup_toggles(qh, 1);

                if (list_empty(&urbp->td_list))
                        td = qh->post_td;
                qh->element = td->link;
                tmp = urbp->td_list.prev;
                ret = 0;
        }

        /* Remove all the TDs we skipped over, from tmp back to the start */
        while (tmp != &urbp->td_list) {
                td = list_entry(tmp, struct uhci_td, list);
                tmp = tmp->prev;

                uhci_remove_td_from_urbp(td);
                uhci_free_td(uhci, td);
        }
        return ret;
}

/*
 * Common result for control, bulk, and interrupt
 */
static int uhci_result_common(struct uhci_hcd *uhci, struct urb *urb)
{
        struct urb_priv *urbp = urb->hcpriv;
        struct uhci_qh *qh = urbp->qh;
        struct uhci_td *td, *tmp;
        unsigned status;
        int ret = 0;

        list_for_each_entry_safe(td, tmp, &urbp->td_list, list) {
                unsigned int ctrlstat;
                int len;

                ctrlstat = td_status(td);
                status = uhci_status_bits(ctrlstat);
                if (status & TD_CTRL_ACTIVE)
                        return -EINPROGRESS;

                len = uhci_actual_length(ctrlstat);
                urb->actual_length += len;

                if (status) {
                        ret = uhci_map_status(status,
                                        uhci_packetout(td_token(td)));
                        if ((debug == 1 && ret != -EPIPE) || debug > 1) {
                                /* Some debugging code */
                                dev_dbg(&urb->dev->dev,
                                                "%s: failed with status %x\n",
                                                __func__, status);

                                if (debug > 1 && errbuf) {
                                        /* Print the chain for debugging */
                                        uhci_show_qh(uhci, urbp->qh, errbuf,
                                                        ERRBUF_LEN, 0);
                                        lprintk(errbuf);
                                }
                        }

                /* Did we receive a short packet? */
                } else if (len < uhci_expected_length(td_token(td))) {

                        /* For control transfers, go to the status TD if
                         * this isn't already the last data TD */
                        if (qh->type == USB_ENDPOINT_XFER_CONTROL) {
                                if (td->list.next != urbp->td_list.prev)
                                        ret = 1;
                        }

                        /* For bulk and interrupt, this may be an error */
                        else if (urb->transfer_flags & URB_SHORT_NOT_OK)
                                ret = -EREMOTEIO;

                        /* Fixup needed only if this isn't the URB's last TD */
                        else if (&td->list != urbp->td_list.prev)
                                ret = 1;
                }

                uhci_remove_td_from_urbp(td);
                if (qh->post_td)
                        uhci_free_td(uhci, qh->post_td);
                qh->post_td = td;

                if (ret != 0)
                        goto err;
        }
        return ret;

err:
        if (ret < 0) {
                /* Note that the queue has stopped and save
                 * the next toggle value */
                qh->element = UHCI_PTR_TERM;
                qh->is_stopped = 1;
                qh->needs_fixup = (qh->type != USB_ENDPOINT_XFER_CONTROL);
                qh->initial_toggle = uhci_toggle(td_token(td)) ^
                                (ret == -EREMOTEIO);

        } else          /* Short packet received */
                ret = uhci_fixup_short_transfer(uhci, qh, urbp);
        return ret;
}

/*
 * 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, frame;
        unsigned long destination, status;
        struct urb_priv *urbp = (struct urb_priv *) urb->hcpriv;

        /* Values must not be too big (could overflow below) */
        if (urb->interval >= UHCI_NUMFRAMES ||
                        urb->number_of_packets >= UHCI_NUMFRAMES)
                return -EFBIG;

        /* Check the period and figure out the starting frame number */
        if (!qh->bandwidth_reserved) {
                qh->period = urb->interval;
                if (urb->transfer_flags & URB_ISO_ASAP) {
                        qh->phase = -1;         /* Find the best phase */
                        i = uhci_check_bandwidth(uhci, qh);
                        if (i)
                                return i;

                        /* Allow a little time to allocate the TDs */
                        uhci_get_current_frame_number(uhci);
                        frame = uhci->frame_number + 10;

                        /* Move forward to the first frame having the
                         * correct phase */
                        urb->start_frame = frame + ((qh->phase - frame) &
                                        (qh->period - 1));
                } else {
                        i = urb->start_frame - uhci->last_iso_frame;
                        if (i <= 0 || i >= UHCI_NUMFRAMES)
                                return -EINVAL;
                        qh->phase = urb->start_frame & (qh->period - 1);
                        i = uhci_check_bandwidth(uhci, qh);
                        if (i)
                                return i;
                }

        } else if (qh->period != urb->interval) {
                return -EINVAL;         /* Can't change the period */

        } else {
                /* Find the next unused frame */
                if (list_empty(&qh->queue)) {
                        frame = qh->iso_frame;
                } else {
                        struct urb *lurb;

                        lurb = list_entry(qh->queue.prev,
                                        struct urb_priv, node)->urb;
                        frame = lurb->start_frame +
                                        lurb->number_of_packets *
                                        lurb->interval;
                }
                if (urb->transfer_flags & URB_ISO_ASAP) {
                        /* Skip some frames if necessary to insure
                         * the start frame is in the future.
                         */
                        uhci_get_current_frame_number(uhci);
                        if (uhci_frame_before_eq(frame, uhci->frame_number)) {
                                frame = uhci->frame_number + 1;
                                frame += ((qh->phase - frame) &
                                        (qh->period - 1));
                        }
                }       /* Otherwise pick up where the last URB leaves off */
                urb->start_frame = frame;
        }

        /* Make sure we won't have to go too far into the future */
        if (uhci_frame_before_eq(uhci->last_iso_frame + UHCI_NUMFRAMES,
                        urb->start_frame + urb->number_of_packets *
                                urb->interval))
                return -EFBIG;

        status = TD_CTRL_ACTIVE | TD_CTRL_IOS;
        destination = (urb->pipe & PIPE_DEVEP_MASK) | usb_packetid(urb->pipe);

        for (i = 0; i < urb->number_of_packets; i++) {
                td = uhci_alloc_td(uhci);
                if (!td)
                        return -ENOMEM;

                uhci_add_td_to_urbp(td, urbp);
                uhci_fill_td(td, status, destination |
                                uhci_explen(urb->iso_frame_desc[i].length),
                                urb->transfer_dma +
                                        urb->iso_frame_desc[i].offset);
        }

        /* Set the interrupt-on-completion flag on the last packet. */
        td->status |= __constant_cpu_to_le32(TD_CTRL_IOC);

        /* Add the TDs to the frame list */
        frame = urb->start_frame;
        list_for_each_entry(td, &urbp->td_list, list) {
                uhci_insert_td_in_frame_list(uhci, td, frame);
                frame += qh->period;
        }

        if (list_empty(&qh->queue)) {
                qh->iso_packet_desc = &urb->iso_frame_desc[0];
                qh->iso_frame = urb->start_frame;
        }

        qh->skel = SKEL_ISO;
        if (!qh->bandwidth_reserved)
                uhci_reserve_bandwidth(uhci, qh);
        return 0;
}

static int uhci_result_isochronous(struct uhci_hcd *uhci, struct urb *urb)
{
        struct uhci_td *td, *tmp;
        struct urb_priv *urbp = urb->hcpriv;
        struct uhci_qh *qh = urbp->qh;

        list_for_each_entry_safe(td, tmp, &urbp->td_list, list) {
                unsigned int ctrlstat;
                int status;
                int actlength;

                if (uhci_frame_before_eq(uhci->cur_iso_frame, qh->iso_frame))
                        return -EINPROGRESS;

                uhci_remove_tds_from_frame(uhci, qh->iso_frame);

                ctrlstat = td_status(td);
                if (ctrlstat & TD_CTRL_ACTIVE) {
                        status = -EXDEV;        /* TD was added too late? */
                } else {
                        status = uhci_map_status(uhci_status_bits(ctrlstat),
                                        usb_pipeout(urb->pipe));
                        actlength = uhci_actual_length(ctrlstat);

                        urb->actual_length += actlength;
                        qh->iso_packet_desc->actual_length = actlength;
                        qh->iso_packet_desc->status = status;
                }
                if (status)
                        urb->error_count++;

                uhci_remove_td_from_urbp(td);
                uhci_free_td(uhci, td);
                qh->iso_frame += qh->period;
                ++qh->iso_packet_desc;
        }
        return 0;
}

static int uhci_urb_enqueue(struct usb_hcd *hcd,
                struct urb *urb, gfp_t mem_flags)
{
        int ret;
        struct uhci_hcd *uhci = hcd_to_uhci(hcd);
        unsigned long flags;
        struct urb_priv *urbp;
        struct uhci_qh *qh;

        spin_lock_irqsave(&uhci->lock, flags);

        ret = usb_hcd_link_urb_to_ep(hcd, urb);
        if (ret)
                goto done_not_linked;

        ret = -ENOMEM;
        urbp = uhci_alloc_urb_priv(uhci, urb);
        if (!urbp)
                goto done;

        if (urb->ep->hcpriv)
                qh = urb->ep->hcpriv;
        else {
                qh = uhci_alloc_qh(uhci, urb->dev, urb->ep);
                if (!qh)
                        goto err_no_qh;
        }
        urbp->qh = qh;

        switch (qh->type) {
        case USB_ENDPOINT_XFER_CONTROL:
                ret = uhci_submit_control(uhci, urb, qh);
                break;
        case USB_ENDPOINT_XFER_BULK:
                ret = uhci_submit_bulk(uhci, urb, qh);
                break;
        case USB_ENDPOINT_XFER_INT:
                ret = uhci_submit_interrupt(uhci, urb, qh);
                break;
        case USB_ENDPOINT_XFER_ISOC:
                urb->error_count = 0;
                ret = uhci_submit_isochronous(uhci, urb, qh);
                break;
        }
        if (ret != 0)
                goto err_submit_failed;

        /* Add this URB to the QH */
        urbp->qh = qh;
        list_add_tail(&urbp->node, &qh->queue);

        /* 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
         * become idle, so we can activate it right away.  But only if the
         * queue isn't stopped. */
        if (qh->queue.next == &urbp->node && !qh->is_stopped) {
                uhci_activate_qh(uhci, qh);
                uhci_urbp_wants_fsbr(uhci, urbp);
        }
        goto done;

err_submit_failed:
        if (qh->state == QH_STATE_IDLE)
                uhci_make_qh_idle(uhci, qh);    /* Reclaim unused QH */
err_no_qh:
        uhci_free_urb_priv(uhci, urbp);
done:
        if (ret)
                usb_hcd_unlink_urb_from_ep(hcd, urb);
done_not_linked:
        spin_unlock_irqrestore(&uhci->lock, flags);
        return ret;
}

static int uhci_urb_dequeue(struct usb_hcd *hcd, struct urb *urb, int status)
{
        struct uhci_hcd *uhci = hcd_to_uhci(hcd);
        unsigned long flags;
        struct uhci_qh *qh;
        int rc;

        spin_lock_irqsave(&uhci->lock, flags);
        rc = usb_hcd_check_unlink_urb(hcd, urb, status);
        if (rc)
                goto done;

        qh = ((struct urb_priv *) urb->hcpriv)->qh;

        /* Remove Isochronous TDs from the frame list ASAP */
        if (qh->type == USB_ENDPOINT_XFER_ISOC) {
                uhci_unlink_isochronous_tds(uhci, urb);
                mb();

                /* If the URB has already started, update the QH unlink time */
                uhci_get_current_frame_number(uhci);
                if (uhci_frame_before_eq(urb->start_frame, uhci->frame_number))
                        qh->unlink_frame = uhci->frame_number;
        }

        uhci_unlink_qh(uhci, qh);

done:
        spin_unlock_irqrestore(&uhci->lock, flags);
        return rc;
}

/*
 * Finish unlinking an URB and give it back
 */
static void uhci_giveback_urb(struct uhci_hcd *uhci, struct uhci_qh *qh,
                struct urb *urb, int status)
__releases(uhci->lock)
__acquires(uhci->lock)
{
        struct urb_priv *urbp = (struct urb_priv *) urb->hcpriv;

        if (qh->type == USB_ENDPOINT_XFER_CONTROL) {

                /* urb->actual_length < 0 means the setup transaction didn't
                 * complete successfully.  Either it failed or the URB was
                 * unlinked first.  Regardless, don't confuse people with a
                 * negative length. */
                urb->actual_length = max(urb->actual_length, 0);
        }

        /* When giving back the first URB in an Isochronous queue,
         * reinitialize the QH's iso-related members for the next URB. */
        else if (qh->type == USB_ENDPOINT_XFER_ISOC &&
                        urbp->node.prev == &qh->queue &&
                        urbp->node.next != &qh->queue) {
                struct urb *nurb = list_entry(urbp->node.next,
                                struct urb_priv, node)->urb;

                qh->iso_packet_desc = &nurb->iso_frame_desc[0];
                qh->iso_frame = nurb->start_frame;
        }

        /* 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_free_urb_priv(uhci, urbp);
        usb_hcd_unlink_urb_from_ep(uhci_to_hcd(uhci), urb);

        spin_unlock(&uhci->lock);
        usb_hcd_giveback_urb(uhci_to_hcd(uhci), urb, status);
        spin_lock(&uhci->lock);

        /* 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);
                if (qh->bandwidth_reserved)
                        uhci_release_bandwidth(uhci, qh);
        }
}

/*
 * Scan the URBs in a QH's queue
 */
#define QH_FINISHED_UNLINKING(qh)                       \
                (qh->state == QH_STATE_UNLINKING &&     \
                uhci->frame_number + uhci->is_stopped != qh->unlink_frame)

static void uhci_scan_qh(struct uhci_hcd *uhci, struct uhci_qh *qh)
{
        struct urb_priv *urbp;
        struct urb *urb;
        int status;

        while (!list_empty(&qh->queue)) {
                urbp = list_entry(qh->queue.next, struct urb_priv, node);
                urb = urbp->urb;

                if (qh->type == USB_ENDPOINT_XFER_ISOC)
                        status = uhci_result_isochronous(uhci, urb);
                else
                        status = uhci_result_common(uhci, urb);
                if (status == -EINPROGRESS)
                        break;

                /* Dequeued but completed URBs can't be given back unless
                 * the QH is stopped or has finished unlinking. */
                if (urb->unlinked) {
                        if (QH_FINISHED_UNLINKING(qh))
                                qh->is_stopped = 1;
                        else if (!qh->is_stopped)
                                return;
                }

                uhci_giveback_urb(uhci, qh, urb, status);
                if (status < 0)
                        break;
        }

        /* If the QH is neither stopped nor finished unlinking (normal case),
         * our work here is done. */
        if (QH_FINISHED_UNLINKING(qh))
                qh->is_stopped = 1;
        else if (!qh->is_stopped)
                return;

        /* Otherwise give back each of the dequeued URBs */
restart:
        list_for_each_entry(urbp, &qh->queue, node) {
                urb = urbp->urb;
                if (urb->unlinked) {

                        /* Fix up the TD links and save the toggles for
                         * non-Isochronous queues.  For Isochronous queues,
                         * test for too-recent dequeues. */
                        if (!uhci_cleanup_queue(uhci, qh, urb)) {
                                qh->is_stopped = 0;
                                return;
                        }
                        uhci_giveback_urb(uhci, qh, urb, 0);
                        goto restart;
                }
        }
        qh->is_stopped = 0;

        /* 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);

                /* If the first URB on the queue wants FSBR but its time
                 * limit has expired, set the next TD to interrupt on
                 * completion before reactivating the QH. */
                urbp = list_entry(qh->queue.next, struct urb_priv, node);
                if (urbp->fsbr && qh->wait_expired) {
                        struct uhci_td *td = list_entry(urbp->td_list.next,
                                        struct uhci_td, list);

                        td->status |= __cpu_to_le32(TD_CTRL_IOC);
                }

                uhci_activate_qh(uhci, qh);
        }

        /* 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);
}

/*
 * Check for queues that have made some forward progress.
 * Returns 0 if the queue is not Isochronous, is ACTIVE, and
 * has not advanced since last examined; 1 otherwise.
 *
 * Early Intel controllers have a bug which causes qh->element sometimes
 * not to advance when a TD completes successfully.  The queue remains
 * stuck on the inactive completed TD.  We detect such cases and advance
 * the element pointer by hand.
 */
static int uhci_advance_check(struct uhci_hcd *uhci, struct uhci_qh *qh)
{
        struct urb_priv *urbp = NULL;
        struct uhci_td *td;
        int ret = 1;
        unsigned status;

        if (qh->type == USB_ENDPOINT_XFER_ISOC)
                goto done;

        /* Treat an UNLINKING queue as though it hasn't advanced.
         * This is okay because reactivation will treat it as though
         * it has advanced, and if it is going to become IDLE then
         * this doesn't matter anyway.  Furthermore it's possible
         * for an UNLINKING queue not to have any URBs at all, or
         * for its first URB not to have any TDs (if it was dequeued
         * just as it completed).  So it's not easy in any case to
         * test whether such queues have advanced. */
        if (qh->state != QH_STATE_ACTIVE) {
                urbp = NULL;
                status = 0;

        } else {
                urbp = list_entry(qh->queue.next, struct urb_priv, node);
                td = list_entry(urbp->td_list.next, struct uhci_td, list);
                status = td_status(td);
                if (!(status & TD_CTRL_ACTIVE)) {

                        /* We're okay, the queue has advanced */
                        qh->wait_expired = 0;
                        qh->advance_jiffies = jiffies;
                        goto done;
                }
                ret = 0;
        }

        /* The queue hasn't advanced; check for timeout */
        if (qh->wait_expired)
                goto done;

        if (time_after(jiffies, qh->advance_jiffies + QH_WAIT_TIMEOUT)) {

                /* Detect the Intel bug and work around it */
                if (qh->post_td && qh_element(qh) == LINK_TO_TD(qh->post_td)) {
                        qh->element = qh->post_td->link;
                        qh->advance_jiffies = jiffies;
                        ret = 1;
                        goto done;
                }

                qh->wait_expired = 1;

                /* If the current URB wants FSBR, unlink it temporarily
                 * so that we can safely set the next TD to interrupt on
                 * completion.  That way we'll know as soon as the queue
                 * starts moving again. */
                if (urbp && urbp->fsbr && !(status & TD_CTRL_IOC))
                        uhci_unlink_qh(uhci, qh);

        } else {
                /* Unmoving but not-yet-expired queues keep FSBR alive */
                if (urbp)
                        uhci_urbp_wants_fsbr(uhci, urbp);
        }

done:
        return ret;
}

/*
 * Process events in the schedule, but only in one thread at a time
 */
static void uhci_scan_schedule(struct uhci_hcd *uhci)
{
        int i;
        struct uhci_qh *qh;

        /* Don't allow re-entrant calls */
        if (uhci->scan_in_progress) {
                uhci->need_rescan = 1;
                return;
        }
        uhci->scan_in_progress = 1;
rescan:
        uhci->need_rescan = 0;
        uhci->fsbr_is_wanted = 0;

        uhci_clear_next_interrupt(uhci);
        uhci_get_current_frame_number(uhci);
        uhci->cur_iso_frame = uhci->frame_number;

        /* 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);

                        if (uhci_advance_check(uhci, qh)) {
                                uhci_scan_qh(uhci, qh);
                                if (qh->state == QH_STATE_ACTIVE) {
                                        uhci_urbp_wants_fsbr(uhci,
        list_entry(qh->queue.next, struct urb_priv, node));
                                }
                        }
                }
        }

        uhci->last_iso_frame = uhci->cur_iso_frame;
        if (uhci->need_rescan)
                goto rescan;
        uhci->scan_in_progress = 0;

        if (uhci->fsbr_is_on && !uhci->fsbr_is_wanted &&
                        !uhci->fsbr_expiring) {
                uhci->fsbr_expiring = 1;
                mod_timer(&uhci->fsbr_timer, jiffies + FSBR_OFF_DELAY);
        }

        if (list_empty(&uhci->skel_unlink_qh->node))
                uhci_clear_next_interrupt(uhci);
        else
                uhci_set_next_interrupt(uhci);
}