Adding upstream version 6.1.76.upstream/6.1.76upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2490 insertions, 0 deletions

diff --git a/drivers/usb/host/ehci-sched.c b/drivers/usb/host/ehci-sched.c
new file mode 100644
index 000000000..bd542b6fc
--- /dev/null
+++ b/drivers/usb/host/ehci-sched.c
@@ -0,0 +1,2490 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (c) 2001-2004 by David Brownell
+ * Copyright (c) 2003 Michal Sojka, for high-speed iso transfers
+ */
+
+/* this file is part of ehci-hcd.c */
+
+/*-------------------------------------------------------------------------*/
+
+/*
+ * EHCI scheduled transaction support:  interrupt, iso, split iso
+ * These are called "periodic" transactions in the EHCI spec.
+ *
+ * Note that for interrupt transfers, the QH/QTD manipulation is shared
+ * with the "asynchronous" transaction support (control/bulk transfers).
+ * The only real difference is in how interrupt transfers are scheduled.
+ *
+ * For ISO, we make an "iso_stream" head to serve the same role as a QH.
+ * It keeps track of every ITD (or SITD) that's linked, and holds enough
+ * pre-calculated schedule data to make appending to the queue be quick.
+ */
+
+static int ehci_get_frame(struct usb_hcd *hcd);
+
+/*
+ * periodic_next_shadow - return "next" pointer on shadow list
+ * @periodic: host pointer to qh/itd/sitd
+ * @tag: hardware tag for type of this record
+ */
+static union ehci_shadow *
+periodic_next_shadow(struct ehci_hcd *ehci, union ehci_shadow *periodic,
+		__hc32 tag)
+{
+	switch (hc32_to_cpu(ehci, tag)) {
+	case Q_TYPE_QH:
+		return &periodic->qh->qh_next;
+	case Q_TYPE_FSTN:
+		return &periodic->fstn->fstn_next;
+	case Q_TYPE_ITD:
+		return &periodic->itd->itd_next;
+	/* case Q_TYPE_SITD: */
+	default:
+		return &periodic->sitd->sitd_next;
+	}
+}
+
+static __hc32 *
+shadow_next_periodic(struct ehci_hcd *ehci, union ehci_shadow *periodic,
+		__hc32 tag)
+{
+	switch (hc32_to_cpu(ehci, tag)) {
+	/* our ehci_shadow.qh is actually software part */
+	case Q_TYPE_QH:
+		return &periodic->qh->hw->hw_next;
+	/* others are hw parts */
+	default:
+		return periodic->hw_next;
+	}
+}
+
+/* caller must hold ehci->lock */
+static void periodic_unlink(struct ehci_hcd *ehci, unsigned frame, void *ptr)
+{
+	union ehci_shadow	*prev_p = &ehci->pshadow[frame];
+	__hc32			*hw_p = &ehci->periodic[frame];
+	union ehci_shadow	here = *prev_p;
+
+	/* find predecessor of "ptr"; hw and shadow lists are in sync */
+	while (here.ptr && here.ptr != ptr) {
+		prev_p = periodic_next_shadow(ehci, prev_p,
+				Q_NEXT_TYPE(ehci, *hw_p));
+		hw_p = shadow_next_periodic(ehci, &here,
+				Q_NEXT_TYPE(ehci, *hw_p));
+		here = *prev_p;
+	}
+	/* an interrupt entry (at list end) could have been shared */
+	if (!here.ptr)
+		return;
+
+	/* update shadow and hardware lists ... the old "next" pointers
+	 * from ptr may still be in use, the caller updates them.
+	 */
+	*prev_p = *periodic_next_shadow(ehci, &here,
+			Q_NEXT_TYPE(ehci, *hw_p));
+
+	if (!ehci->use_dummy_qh ||
+	    *shadow_next_periodic(ehci, &here, Q_NEXT_TYPE(ehci, *hw_p))
+			!= EHCI_LIST_END(ehci))
+		*hw_p = *shadow_next_periodic(ehci, &here,
+				Q_NEXT_TYPE(ehci, *hw_p));
+	else
+		*hw_p = cpu_to_hc32(ehci, ehci->dummy->qh_dma);
+}
+
+/*-------------------------------------------------------------------------*/
+
+/* Bandwidth and TT management */
+
+/* Find the TT data structure for this device; create it if necessary */
+static struct ehci_tt *find_tt(struct usb_device *udev)
+{
+	struct usb_tt		*utt = udev->tt;
+	struct ehci_tt		*tt, **tt_index, **ptt;
+	unsigned		port;
+	bool			allocated_index = false;
+
+	if (!utt)
+		return NULL;		/* Not below a TT */
+
+	/*
+	 * Find/create our data structure.
+	 * For hubs with a single TT, we get it directly.
+	 * For hubs with multiple TTs, there's an extra level of pointers.
+	 */
+	tt_index = NULL;
+	if (utt->multi) {
+		tt_index = utt->hcpriv;
+		if (!tt_index) {		/* Create the index array */
+			tt_index = kcalloc(utt->hub->maxchild,
+					   sizeof(*tt_index),
+					   GFP_ATOMIC);
+			if (!tt_index)
+				return ERR_PTR(-ENOMEM);
+			utt->hcpriv = tt_index;
+			allocated_index = true;
+		}
+		port = udev->ttport - 1;
+		ptt = &tt_index[port];
+	} else {
+		port = 0;
+		ptt = (struct ehci_tt **) &utt->hcpriv;
+	}
+
+	tt = *ptt;
+	if (!tt) {				/* Create the ehci_tt */
+		struct ehci_hcd		*ehci =
+				hcd_to_ehci(bus_to_hcd(udev->bus));
+
+		tt = kzalloc(sizeof(*tt), GFP_ATOMIC);
+		if (!tt) {
+			if (allocated_index) {
+				utt->hcpriv = NULL;
+				kfree(tt_index);
+			}
+			return ERR_PTR(-ENOMEM);
+		}
+		list_add_tail(&tt->tt_list, &ehci->tt_list);
+		INIT_LIST_HEAD(&tt->ps_list);
+		tt->usb_tt = utt;
+		tt->tt_port = port;
+		*ptt = tt;
+	}
+
+	return tt;
+}
+
+/* Release the TT above udev, if it's not in use */
+static void drop_tt(struct usb_device *udev)
+{
+	struct usb_tt		*utt = udev->tt;
+	struct ehci_tt		*tt, **tt_index, **ptt;
+	int			cnt, i;
+
+	if (!utt || !utt->hcpriv)
+		return;		/* Not below a TT, or never allocated */
+
+	cnt = 0;
+	if (utt->multi) {
+		tt_index = utt->hcpriv;
+		ptt = &tt_index[udev->ttport - 1];
+
+		/* How many entries are left in tt_index? */
+		for (i = 0; i < utt->hub->maxchild; ++i)
+			cnt += !!tt_index[i];
+	} else {
+		tt_index = NULL;
+		ptt = (struct ehci_tt **) &utt->hcpriv;
+	}
+
+	tt = *ptt;
+	if (!tt || !list_empty(&tt->ps_list))
+		return;		/* never allocated, or still in use */
+
+	list_del(&tt->tt_list);
+	*ptt = NULL;
+	kfree(tt);
+	if (cnt == 1) {
+		utt->hcpriv = NULL;
+		kfree(tt_index);
+	}
+}
+
+static void bandwidth_dbg(struct ehci_hcd *ehci, int sign, char *type,
+		struct ehci_per_sched *ps)
+{
+	dev_dbg(&ps->udev->dev,
+			"ep %02x: %s %s @ %u+%u (%u.%u+%u) [%u/%u us] mask %04x\n",
+			ps->ep->desc.bEndpointAddress,
+			(sign >= 0 ? "reserve" : "release"), type,
+			(ps->bw_phase << 3) + ps->phase_uf, ps->bw_uperiod,
+			ps->phase, ps->phase_uf, ps->period,
+			ps->usecs, ps->c_usecs, ps->cs_mask);
+}
+
+static void reserve_release_intr_bandwidth(struct ehci_hcd *ehci,
+		struct ehci_qh *qh, int sign)
+{
+	unsigned		start_uf;
+	unsigned		i, j, m;
+	int			usecs = qh->ps.usecs;
+	int			c_usecs = qh->ps.c_usecs;
+	int			tt_usecs = qh->ps.tt_usecs;
+	struct ehci_tt		*tt;
+
+	if (qh->ps.phase == NO_FRAME)	/* Bandwidth wasn't reserved */
+		return;
+	start_uf = qh->ps.bw_phase << 3;
+
+	bandwidth_dbg(ehci, sign, "intr", &qh->ps);
+
+	if (sign < 0) {		/* Release bandwidth */
+		usecs = -usecs;
+		c_usecs = -c_usecs;
+		tt_usecs = -tt_usecs;
+	}
+
+	/* Entire transaction (high speed) or start-split (full/low speed) */
+	for (i = start_uf + qh->ps.phase_uf; i < EHCI_BANDWIDTH_SIZE;
+			i += qh->ps.bw_uperiod)
+		ehci->bandwidth[i] += usecs;
+
+	/* Complete-split (full/low speed) */
+	if (qh->ps.c_usecs) {
+		/* NOTE: adjustments needed for FSTN */
+		for (i = start_uf; i < EHCI_BANDWIDTH_SIZE;
+				i += qh->ps.bw_uperiod) {
+			for ((j = 2, m = 1 << (j+8)); j < 8; (++j, m <<= 1)) {
+				if (qh->ps.cs_mask & m)
+					ehci->bandwidth[i+j] += c_usecs;
+			}
+		}
+	}
+
+	/* FS/LS bus bandwidth */
+	if (tt_usecs) {
+		/*
+		 * find_tt() will not return any error here as we have
+		 * already called find_tt() before calling this function
+		 * and checked for any error return. The previous call
+		 * would have created the data structure.
+		 */
+		tt = find_tt(qh->ps.udev);
+		if (sign > 0)
+			list_add_tail(&qh->ps.ps_list, &tt->ps_list);
+		else
+			list_del(&qh->ps.ps_list);
+
+		for (i = start_uf >> 3; i < EHCI_BANDWIDTH_FRAMES;
+				i += qh->ps.bw_period)
+			tt->bandwidth[i] += tt_usecs;
+	}
+}
+
+/*-------------------------------------------------------------------------*/
+
+static void compute_tt_budget(u8 budget_table[EHCI_BANDWIDTH_SIZE],
+		struct ehci_tt *tt)
+{
+	struct ehci_per_sched	*ps;
+	unsigned		uframe, uf, x;
+	u8			*budget_line;
+
+	if (!tt)
+		return;
+	memset(budget_table, 0, EHCI_BANDWIDTH_SIZE);
+
+	/* Add up the contributions from all the endpoints using this TT */
+	list_for_each_entry(ps, &tt->ps_list, ps_list) {
+		for (uframe = ps->bw_phase << 3; uframe < EHCI_BANDWIDTH_SIZE;
+				uframe += ps->bw_uperiod) {
+			budget_line = &budget_table[uframe];
+			x = ps->tt_usecs;
+
+			/* propagate the time forward */
+			for (uf = ps->phase_uf; uf < 8; ++uf) {
+				x += budget_line[uf];
+
+				/* Each microframe lasts 125 us */
+				if (x <= 125) {
+					budget_line[uf] = x;
+					break;
+				}
+				budget_line[uf] = 125;
+				x -= 125;
+			}
+		}
+	}
+}
+
+static int __maybe_unused same_tt(struct usb_device *dev1,
+		struct usb_device *dev2)
+{
+	if (!dev1->tt || !dev2->tt)
+		return 0;
+	if (dev1->tt != dev2->tt)
+		return 0;
+	if (dev1->tt->multi)
+		return dev1->ttport == dev2->ttport;
+	else
+		return 1;
+}
+
+#ifdef CONFIG_USB_EHCI_TT_NEWSCHED
+
+static const unsigned char
+max_tt_usecs[] = { 125, 125, 125, 125, 125, 125, 30, 0 };
+
+/* carryover low/fullspeed bandwidth that crosses uframe boundries */
+static inline void carryover_tt_bandwidth(unsigned short tt_usecs[8])
+{
+	int i;
+
+	for (i = 0; i < 7; i++) {
+		if (max_tt_usecs[i] < tt_usecs[i]) {
+			tt_usecs[i+1] += tt_usecs[i] - max_tt_usecs[i];
+			tt_usecs[i] = max_tt_usecs[i];
+		}
+	}
+}
+
+/*
+ * Return true if the device's tt's downstream bus is available for a
+ * periodic transfer of the specified length (usecs), starting at the
+ * specified frame/uframe.  Note that (as summarized in section 11.19
+ * of the usb 2.0 spec) TTs can buffer multiple transactions for each
+ * uframe.
+ *
+ * The uframe parameter is when the fullspeed/lowspeed transfer
+ * should be executed in "B-frame" terms, which is the same as the
+ * highspeed ssplit's uframe (which is in "H-frame" terms).  For example
+ * a ssplit in "H-frame" 0 causes a transfer in "B-frame" 0.
+ * See the EHCI spec sec 4.5 and fig 4.7.
+ *
+ * This checks if the full/lowspeed bus, at the specified starting uframe,
+ * has the specified bandwidth available, according to rules listed
+ * in USB 2.0 spec section 11.18.1 fig 11-60.
+ *
+ * This does not check if the transfer would exceed the max ssplit
+ * limit of 16, specified in USB 2.0 spec section 11.18.4 requirement #4,
+ * since proper scheduling limits ssplits to less than 16 per uframe.
+ */
+static int tt_available(
+	struct ehci_hcd		*ehci,
+	struct ehci_per_sched	*ps,
+	struct ehci_tt		*tt,
+	unsigned		frame,
+	unsigned		uframe
+)
+{
+	unsigned		period = ps->bw_period;
+	unsigned		usecs = ps->tt_usecs;
+
+	if ((period == 0) || (uframe >= 7))	/* error */
+		return 0;
+
+	for (frame &= period - 1; frame < EHCI_BANDWIDTH_FRAMES;
+			frame += period) {
+		unsigned	i, uf;
+		unsigned short	tt_usecs[8];
+
+		if (tt->bandwidth[frame] + usecs > 900)
+			return 0;
+
+		uf = frame << 3;
+		for (i = 0; i < 8; (++i, ++uf))
+			tt_usecs[i] = ehci->tt_budget[uf];
+
+		if (max_tt_usecs[uframe] <= tt_usecs[uframe])
+			return 0;
+
+		/* special case for isoc transfers larger than 125us:
+		 * the first and each subsequent fully used uframe
+		 * must be empty, so as to not illegally delay
+		 * already scheduled transactions
+		 */
+		if (usecs > 125) {
+			int ufs = (usecs / 125);
+
+			for (i = uframe; i < (uframe + ufs) && i < 8; i++)
+				if (tt_usecs[i] > 0)
+					return 0;
+		}
+
+		tt_usecs[uframe] += usecs;
+
+		carryover_tt_bandwidth(tt_usecs);
+
+		/* fail if the carryover pushed bw past the last uframe's limit */
+		if (max_tt_usecs[7] < tt_usecs[7])
+			return 0;
+	}
+
+	return 1;
+}
+
+#else
+
+/* return true iff the device's transaction translator is available
+ * for a periodic transfer starting at the specified frame, using
+ * all the uframes in the mask.
+ */
+static int tt_no_collision(
+	struct ehci_hcd		*ehci,
+	unsigned		period,
+	struct usb_device	*dev,
+	unsigned		frame,
+	u32			uf_mask
+)
+{
+	if (period == 0)	/* error */
+		return 0;
+
+	/* note bandwidth wastage:  split never follows csplit
+	 * (different dev or endpoint) until the next uframe.
+	 * calling convention doesn't make that distinction.
+	 */
+	for (; frame < ehci->periodic_size; frame += period) {
+		union ehci_shadow	here;
+		__hc32			type;
+		struct ehci_qh_hw	*hw;
+
+		here = ehci->pshadow[frame];
+		type = Q_NEXT_TYPE(ehci, ehci->periodic[frame]);
+		while (here.ptr) {
+			switch (hc32_to_cpu(ehci, type)) {
+			case Q_TYPE_ITD:
+				type = Q_NEXT_TYPE(ehci, here.itd->hw_next);
+				here = here.itd->itd_next;
+				continue;
+			case Q_TYPE_QH:
+				hw = here.qh->hw;
+				if (same_tt(dev, here.qh->ps.udev)) {
+					u32		mask;
+
+					mask = hc32_to_cpu(ehci,
+							hw->hw_info2);
+					/* "knows" no gap is needed */
+					mask |= mask >> 8;
+					if (mask & uf_mask)
+						break;
+				}
+				type = Q_NEXT_TYPE(ehci, hw->hw_next);
+				here = here.qh->qh_next;
+				continue;
+			case Q_TYPE_SITD:
+				if (same_tt(dev, here.sitd->urb->dev)) {
+					u16		mask;
+
+					mask = hc32_to_cpu(ehci, here.sitd
+								->hw_uframe);
+					/* FIXME assumes no gap for IN! */
+					mask |= mask >> 8;
+					if (mask & uf_mask)
+						break;
+				}
+				type = Q_NEXT_TYPE(ehci, here.sitd->hw_next);
+				here = here.sitd->sitd_next;
+				continue;
+			/* case Q_TYPE_FSTN: */
+			default:
+				ehci_dbg(ehci,
+					"periodic frame %d bogus type %d\n",
+					frame, type);
+			}
+
+			/* collision or error */
+			return 0;
+		}
+	}
+
+	/* no collision */
+	return 1;
+}
+
+#endif /* CONFIG_USB_EHCI_TT_NEWSCHED */
+
+/*-------------------------------------------------------------------------*/
+
+static void enable_periodic(struct ehci_hcd *ehci)
+{
+	if (ehci->periodic_count++)
+		return;
+
+	/* Stop waiting to turn off the periodic schedule */
+	ehci->enabled_hrtimer_events &= ~BIT(EHCI_HRTIMER_DISABLE_PERIODIC);
+
+	/* Don't start the schedule until PSS is 0 */
+	ehci_poll_PSS(ehci);
+	turn_on_io_watchdog(ehci);
+}
+
+static void disable_periodic(struct ehci_hcd *ehci)
+{
+	if (--ehci->periodic_count)
+		return;
+
+	/* Don't turn off the schedule until PSS is 1 */
+	ehci_poll_PSS(ehci);
+}
+
+/*-------------------------------------------------------------------------*/
+
+/* periodic schedule slots have iso tds (normal or split) first, then a
+ * sparse tree for active interrupt transfers.
+ *
+ * this just links in a qh; caller guarantees uframe masks are set right.
+ * no FSTN support (yet; ehci 0.96+)
+ */
+static void qh_link_periodic(struct ehci_hcd *ehci, struct ehci_qh *qh)
+{
+	unsigned	i;
+	unsigned	period = qh->ps.period;
+
+	dev_dbg(&qh->ps.udev->dev,
+		"link qh%d-%04x/%p start %d [%d/%d us]\n",
+		period, hc32_to_cpup(ehci, &qh->hw->hw_info2)
+			& (QH_CMASK | QH_SMASK),
+		qh, qh->ps.phase, qh->ps.usecs, qh->ps.c_usecs);
+
+	/* high bandwidth, or otherwise every microframe */
+	if (period == 0)
+		period = 1;
+
+	for (i = qh->ps.phase; i < ehci->periodic_size; i += period) {
+		union ehci_shadow	*prev = &ehci->pshadow[i];
+		__hc32			*hw_p = &ehci->periodic[i];
+		union ehci_shadow	here = *prev;
+		__hc32			type = 0;
+
+		/* skip the iso nodes at list head */
+		while (here.ptr) {
+			type = Q_NEXT_TYPE(ehci, *hw_p);
+			if (type == cpu_to_hc32(ehci, Q_TYPE_QH))
+				break;
+			prev = periodic_next_shadow(ehci, prev, type);
+			hw_p = shadow_next_periodic(ehci, &here, type);
+			here = *prev;
+		}
+
+		/* sorting each branch by period (slow-->fast)
+		 * enables sharing interior tree nodes
+		 */
+		while (here.ptr && qh != here.qh) {
+			if (qh->ps.period > here.qh->ps.period)
+				break;
+			prev = &here.qh->qh_next;
+			hw_p = &here.qh->hw->hw_next;
+			here = *prev;
+		}
+		/* link in this qh, unless some earlier pass did that */
+		if (qh != here.qh) {
+			qh->qh_next = here;
+			if (here.qh)
+				qh->hw->hw_next = *hw_p;
+			wmb();
+			prev->qh = qh;
+			*hw_p = QH_NEXT(ehci, qh->qh_dma);
+		}
+	}
+	qh->qh_state = QH_STATE_LINKED;
+	qh->xacterrs = 0;
+	qh->unlink_reason = 0;
+
+	/* update per-qh bandwidth for debugfs */
+	ehci_to_hcd(ehci)->self.bandwidth_allocated += qh->ps.bw_period
+		? ((qh->ps.usecs + qh->ps.c_usecs) / qh->ps.bw_period)
+		: (qh->ps.usecs * 8);
+
+	list_add(&qh->intr_node, &ehci->intr_qh_list);
+
+	/* maybe enable periodic schedule processing */
+	++ehci->intr_count;
+	enable_periodic(ehci);
+}
+
+static void qh_unlink_periodic(struct ehci_hcd *ehci, struct ehci_qh *qh)
+{
+	unsigned	i;
+	unsigned	period;
+
+	/*
+	 * If qh is for a low/full-speed device, simply unlinking it
+	 * could interfere with an ongoing split transaction.  To unlink
+	 * it safely would require setting the QH_INACTIVATE bit and
+	 * waiting at least one frame, as described in EHCI 4.12.2.5.
+	 *
+	 * We won't bother with any of this.  Instead, we assume that the
+	 * only reason for unlinking an interrupt QH while the current URB
+	 * is still active is to dequeue all the URBs (flush the whole
+	 * endpoint queue).
+	 *
+	 * If rebalancing the periodic schedule is ever implemented, this
+	 * approach will no longer be valid.
+	 */
+
+	/* high bandwidth, or otherwise part of every microframe */
+	period = qh->ps.period ? : 1;
+
+	for (i = qh->ps.phase; i < ehci->periodic_size; i += period)
+		periodic_unlink(ehci, i, qh);
+
+	/* update per-qh bandwidth for debugfs */
+	ehci_to_hcd(ehci)->self.bandwidth_allocated -= qh->ps.bw_period
+		? ((qh->ps.usecs + qh->ps.c_usecs) / qh->ps.bw_period)
+		: (qh->ps.usecs * 8);
+
+	dev_dbg(&qh->ps.udev->dev,
+		"unlink qh%d-%04x/%p start %d [%d/%d us]\n",
+		qh->ps.period,
+		hc32_to_cpup(ehci, &qh->hw->hw_info2) & (QH_CMASK | QH_SMASK),
+		qh, qh->ps.phase, qh->ps.usecs, qh->ps.c_usecs);
+
+	/* qh->qh_next still "live" to HC */
+	qh->qh_state = QH_STATE_UNLINK;
+	qh->qh_next.ptr = NULL;
+
+	if (ehci->qh_scan_next == qh)
+		ehci->qh_scan_next = list_entry(qh->intr_node.next,
+				struct ehci_qh, intr_node);
+	list_del(&qh->intr_node);
+}
+
+static void cancel_unlink_wait_intr(struct ehci_hcd *ehci, struct ehci_qh *qh)
+{
+	if (qh->qh_state != QH_STATE_LINKED ||
+			list_empty(&qh->unlink_node))
+		return;
+
+	list_del_init(&qh->unlink_node);
+
+	/*
+	 * TODO: disable the event of EHCI_HRTIMER_START_UNLINK_INTR for
+	 * avoiding unnecessary CPU wakeup
+	 */
+}
+
+static void start_unlink_intr(struct ehci_hcd *ehci, struct ehci_qh *qh)
+{
+	/* If the QH isn't linked then there's nothing we can do. */
+	if (qh->qh_state != QH_STATE_LINKED)
+		return;
+
+	/* if the qh is waiting for unlink, cancel it now */
+	cancel_unlink_wait_intr(ehci, qh);
+
+	qh_unlink_periodic(ehci, qh);
+
+	/* Make sure the unlinks are visible before starting the timer */
+	wmb();
+
+	/*
+	 * The EHCI spec doesn't say how long it takes the controller to
+	 * stop accessing an unlinked interrupt QH.  The timer delay is
+	 * 9 uframes; presumably that will be long enough.
+	 */
+	qh->unlink_cycle = ehci->intr_unlink_cycle;
+
+	/* New entries go at the end of the intr_unlink list */
+	list_add_tail(&qh->unlink_node, &ehci->intr_unlink);
+
+	if (ehci->intr_unlinking)
+		;	/* Avoid recursive calls */
+	else if (ehci->rh_state < EHCI_RH_RUNNING)
+		ehci_handle_intr_unlinks(ehci);
+	else if (ehci->intr_unlink.next == &qh->unlink_node) {
+		ehci_enable_event(ehci, EHCI_HRTIMER_UNLINK_INTR, true);
+		++ehci->intr_unlink_cycle;
+	}
+}
+
+/*
+ * It is common only one intr URB is scheduled on one qh, and
+ * given complete() is run in tasklet context, introduce a bit
+ * delay to avoid unlink qh too early.
+ */
+static void start_unlink_intr_wait(struct ehci_hcd *ehci,
+				   struct ehci_qh *qh)
+{
+	qh->unlink_cycle = ehci->intr_unlink_wait_cycle;
+
+	/* New entries go at the end of the intr_unlink_wait list */
+	list_add_tail(&qh->unlink_node, &ehci->intr_unlink_wait);
+
+	if (ehci->rh_state < EHCI_RH_RUNNING)
+		ehci_handle_start_intr_unlinks(ehci);
+	else if (ehci->intr_unlink_wait.next == &qh->unlink_node) {
+		ehci_enable_event(ehci, EHCI_HRTIMER_START_UNLINK_INTR, true);
+		++ehci->intr_unlink_wait_cycle;
+	}
+}
+
+static void end_unlink_intr(struct ehci_hcd *ehci, struct ehci_qh *qh)
+{
+	struct ehci_qh_hw	*hw = qh->hw;
+	int			rc;
+
+	qh->qh_state = QH_STATE_IDLE;
+	hw->hw_next = EHCI_LIST_END(ehci);
+
+	if (!list_empty(&qh->qtd_list))
+		qh_completions(ehci, qh);
+
+	/* reschedule QH iff another request is queued */
+	if (!list_empty(&qh->qtd_list) && ehci->rh_state == EHCI_RH_RUNNING) {
+		rc = qh_schedule(ehci, qh);
+		if (rc == 0) {
+			qh_refresh(ehci, qh);
+			qh_link_periodic(ehci, qh);
+		}
+
+		/* An error here likely indicates handshake failure
+		 * or no space left in the schedule.  Neither fault
+		 * should happen often ...
+		 *
+		 * FIXME kill the now-dysfunctional queued urbs
+		 */
+		else {
+			ehci_err(ehci, "can't reschedule qh %p, err %d\n",
+					qh, rc);
+		}
+	}
+
+	/* maybe turn off periodic schedule */
+	--ehci->intr_count;
+	disable_periodic(ehci);
+}
+
+/*-------------------------------------------------------------------------*/
+
+static int check_period(
+	struct ehci_hcd *ehci,
+	unsigned	frame,
+	unsigned	uframe,
+	unsigned	uperiod,
+	unsigned	usecs
+) {
+	/* complete split running into next frame?
+	 * given FSTN support, we could sometimes check...
+	 */
+	if (uframe >= 8)
+		return 0;
+
+	/* convert "usecs we need" to "max already claimed" */
+	usecs = ehci->uframe_periodic_max - usecs;
+
+	for (uframe += frame << 3; uframe < EHCI_BANDWIDTH_SIZE;
+			uframe += uperiod) {
+		if (ehci->bandwidth[uframe] > usecs)
+			return 0;
+	}
+
+	/* success! */
+	return 1;
+}
+
+static int check_intr_schedule(
+	struct ehci_hcd		*ehci,
+	unsigned		frame,
+	unsigned		uframe,
+	struct ehci_qh		*qh,
+	unsigned		*c_maskp,
+	struct ehci_tt		*tt
+)
+{
+	int		retval = -ENOSPC;
+	u8		mask = 0;
+
+	if (qh->ps.c_usecs && uframe >= 6)	/* FSTN territory? */
+		goto done;
+
+	if (!check_period(ehci, frame, uframe, qh->ps.bw_uperiod, qh->ps.usecs))
+		goto done;
+	if (!qh->ps.c_usecs) {
+		retval = 0;
+		*c_maskp = 0;
+		goto done;
+	}
+
+#ifdef CONFIG_USB_EHCI_TT_NEWSCHED
+	if (tt_available(ehci, &qh->ps, tt, frame, uframe)) {
+		unsigned i;
+
+		/* TODO : this may need FSTN for SSPLIT in uframe 5. */
+		for (i = uframe+2; i < 8 && i <= uframe+4; i++)
+			if (!check_period(ehci, frame, i,
+					qh->ps.bw_uperiod, qh->ps.c_usecs))
+				goto done;
+			else
+				mask |= 1 << i;
+
+		retval = 0;
+
+		*c_maskp = mask;
+	}
+#else
+	/* Make sure this tt's buffer is also available for CSPLITs.
+	 * We pessimize a bit; probably the typical full speed case
+	 * doesn't need the second CSPLIT.
+	 *
+	 * NOTE:  both SPLIT and CSPLIT could be checked in just
+	 * one smart pass...
+	 */
+	mask = 0x03 << (uframe + qh->gap_uf);
+	*c_maskp = mask;
+
+	mask |= 1 << uframe;
+	if (tt_no_collision(ehci, qh->ps.bw_period, qh->ps.udev, frame, mask)) {
+		if (!check_period(ehci, frame, uframe + qh->gap_uf + 1,
+				qh->ps.bw_uperiod, qh->ps.c_usecs))
+			goto done;
+		if (!check_period(ehci, frame, uframe + qh->gap_uf,
+				qh->ps.bw_uperiod, qh->ps.c_usecs))
+			goto done;
+		retval = 0;
+	}
+#endif
+done:
+	return retval;
+}
+
+/* "first fit" scheduling policy used the first time through,
+ * or when the previous schedule slot can't be re-used.
+ */
+static int qh_schedule(struct ehci_hcd *ehci, struct ehci_qh *qh)
+{
+	int		status = 0;
+	unsigned	uframe;
+	unsigned	c_mask;
+	struct ehci_qh_hw	*hw = qh->hw;
+	struct ehci_tt		*tt;
+
+	hw->hw_next = EHCI_LIST_END(ehci);
+
+	/* reuse the previous schedule slots, if we can */
+	if (qh->ps.phase != NO_FRAME) {
+		ehci_dbg(ehci, "reused qh %p schedule\n", qh);
+		return 0;
+	}
+
+	uframe = 0;
+	c_mask = 0;
+	tt = find_tt(qh->ps.udev);
+	if (IS_ERR(tt)) {
+		status = PTR_ERR(tt);
+		goto done;
+	}
+	compute_tt_budget(ehci->tt_budget, tt);
+
+	/* else scan the schedule to find a group of slots such that all
+	 * uframes have enough periodic bandwidth available.
+	 */
+	/* "normal" case, uframing flexible except with splits */
+	if (qh->ps.bw_period) {
+		int		i;
+		unsigned	frame;
+
+		for (i = qh->ps.bw_period; i > 0; --i) {
+			frame = ++ehci->random_frame & (qh->ps.bw_period - 1);
+			for (uframe = 0; uframe < 8; uframe++) {
+				status = check_intr_schedule(ehci,
+						frame, uframe, qh, &c_mask, tt);
+				if (status == 0)
+					goto got_it;
+			}
+		}
+
+	/* qh->ps.bw_period == 0 means every uframe */
+	} else {
+		status = check_intr_schedule(ehci, 0, 0, qh, &c_mask, tt);
+	}
+	if (status)
+		goto done;
+
+ got_it:
+	qh->ps.phase = (qh->ps.period ? ehci->random_frame &
+			(qh->ps.period - 1) : 0);
+	qh->ps.bw_phase = qh->ps.phase & (qh->ps.bw_period - 1);
+	qh->ps.phase_uf = uframe;
+	qh->ps.cs_mask = qh->ps.period ?
+			(c_mask << 8) | (1 << uframe) :
+			QH_SMASK;
+
+	/* reset S-frame and (maybe) C-frame masks */
+	hw->hw_info2 &= cpu_to_hc32(ehci, ~(QH_CMASK | QH_SMASK));
+	hw->hw_info2 |= cpu_to_hc32(ehci, qh->ps.cs_mask);
+	reserve_release_intr_bandwidth(ehci, qh, 1);
+
+done:
+	return status;
+}
+
+static int intr_submit(
+	struct ehci_hcd		*ehci,
+	struct urb		*urb,
+	struct list_head	*qtd_list,
+	gfp_t			mem_flags
+) {
+	unsigned		epnum;
+	unsigned long		flags;
+	struct ehci_qh		*qh;
+	int			status;
+	struct list_head	empty;
+
+	/* get endpoint and transfer/schedule data */
+	epnum = urb->ep->desc.bEndpointAddress;
+
+	spin_lock_irqsave(&ehci->lock, flags);
+
+	if (unlikely(!HCD_HW_ACCESSIBLE(ehci_to_hcd(ehci)))) {
+		status = -ESHUTDOWN;
+		goto done_not_linked;
+	}
+	status = usb_hcd_link_urb_to_ep(ehci_to_hcd(ehci), urb);
+	if (unlikely(status))
+		goto done_not_linked;
+
+	/* get qh and force any scheduling errors */
+	INIT_LIST_HEAD(&empty);
+	qh = qh_append_tds(ehci, urb, &empty, epnum, &urb->ep->hcpriv);
+	if (qh == NULL) {
+		status = -ENOMEM;
+		goto done;
+	}
+	if (qh->qh_state == QH_STATE_IDLE) {
+		status = qh_schedule(ehci, qh);
+		if (status)
+			goto done;
+	}
+
+	/* then queue the urb's tds to the qh */
+	qh = qh_append_tds(ehci, urb, qtd_list, epnum, &urb->ep->hcpriv);
+	BUG_ON(qh == NULL);
+
+	/* stuff into the periodic schedule */
+	if (qh->qh_state == QH_STATE_IDLE) {
+		qh_refresh(ehci, qh);
+		qh_link_periodic(ehci, qh);
+	} else {
+		/* cancel unlink wait for the qh */
+		cancel_unlink_wait_intr(ehci, qh);
+	}
+
+	/* ... update usbfs periodic stats */
+	ehci_to_hcd(ehci)->self.bandwidth_int_reqs++;
+
+done:
+	if (unlikely(status))
+		usb_hcd_unlink_urb_from_ep(ehci_to_hcd(ehci), urb);
+done_not_linked:
+	spin_unlock_irqrestore(&ehci->lock, flags);
+	if (status)
+		qtd_list_free(ehci, urb, qtd_list);
+
+	return status;
+}
+
+static void scan_intr(struct ehci_hcd *ehci)
+{
+	struct ehci_qh		*qh;
+
+	list_for_each_entry_safe(qh, ehci->qh_scan_next, &ehci->intr_qh_list,
+			intr_node) {
+
+		/* clean any finished work for this qh */
+		if (!list_empty(&qh->qtd_list)) {
+			int temp;
+
+			/*
+			 * Unlinks could happen here; completion reporting
+			 * drops the lock.  That's why ehci->qh_scan_next
+			 * always holds the next qh to scan; if the next qh
+			 * gets unlinked then ehci->qh_scan_next is adjusted
+			 * in qh_unlink_periodic().
+			 */
+			temp = qh_completions(ehci, qh);
+			if (unlikely(temp))
+				start_unlink_intr(ehci, qh);
+			else if (unlikely(list_empty(&qh->qtd_list) &&
+					qh->qh_state == QH_STATE_LINKED))
+				start_unlink_intr_wait(ehci, qh);
+		}
+	}
+}
+
+/*-------------------------------------------------------------------------*/
+
+/* ehci_iso_stream ops work with both ITD and SITD */
+
+static struct ehci_iso_stream *
+iso_stream_alloc(gfp_t mem_flags)
+{
+	struct ehci_iso_stream *stream;
+
+	stream = kzalloc(sizeof(*stream), mem_flags);
+	if (likely(stream != NULL)) {
+		INIT_LIST_HEAD(&stream->td_list);
+		INIT_LIST_HEAD(&stream->free_list);
+		stream->next_uframe = NO_FRAME;
+		stream->ps.phase = NO_FRAME;
+	}
+	return stream;
+}
+
+static void
+iso_stream_init(
+	struct ehci_hcd		*ehci,
+	struct ehci_iso_stream	*stream,
+	struct urb		*urb
+)
+{
+	static const u8 smask_out[] = { 0x01, 0x03, 0x07, 0x0f, 0x1f, 0x3f };
+
+	struct usb_device	*dev = urb->dev;
+	u32			buf1;
+	unsigned		epnum, maxp;
+	int			is_input;
+	unsigned		tmp;
+
+	/*
+	 * this might be a "high bandwidth" highspeed endpoint,
+	 * as encoded in the ep descriptor's wMaxPacket field
+	 */
+	epnum = usb_pipeendpoint(urb->pipe);
+	is_input = usb_pipein(urb->pipe) ? USB_DIR_IN : 0;
+	maxp = usb_endpoint_maxp(&urb->ep->desc);
+	buf1 = is_input ? 1 << 11 : 0;
+
+	/* knows about ITD vs SITD */
+	if (dev->speed == USB_SPEED_HIGH) {
+		unsigned multi = usb_endpoint_maxp_mult(&urb->ep->desc);
+
+		stream->highspeed = 1;
+
+		buf1 |= maxp;
+		maxp *= multi;
+
+		stream->buf0 = cpu_to_hc32(ehci, (epnum << 8) | dev->devnum);
+		stream->buf1 = cpu_to_hc32(ehci, buf1);
+		stream->buf2 = cpu_to_hc32(ehci, multi);
+
+		/* usbfs wants to report the average usecs per frame tied up
+		 * when transfers on this endpoint are scheduled ...
+		 */
+		stream->ps.usecs = HS_USECS_ISO(maxp);
+
+		/* period for bandwidth allocation */
+		tmp = min_t(unsigned, EHCI_BANDWIDTH_SIZE,
+				1 << (urb->ep->desc.bInterval - 1));
+
+		/* Allow urb->interval to override */
+		stream->ps.bw_uperiod = min_t(unsigned, tmp, urb->interval);
+
+		stream->uperiod = urb->interval;
+		stream->ps.period = urb->interval >> 3;
+		stream->bandwidth = stream->ps.usecs * 8 /
+				stream->ps.bw_uperiod;
+
+	} else {
+		u32		addr;
+		int		think_time;
+		int		hs_transfers;
+
+		addr = dev->ttport << 24;
+		if (!ehci_is_TDI(ehci)
+				|| (dev->tt->hub !=
+					ehci_to_hcd(ehci)->self.root_hub))
+			addr |= dev->tt->hub->devnum << 16;
+		addr |= epnum << 8;
+		addr |= dev->devnum;
+		stream->ps.usecs = HS_USECS_ISO(maxp);
+		think_time = dev->tt->think_time;
+		stream->ps.tt_usecs = NS_TO_US(think_time + usb_calc_bus_time(
+				dev->speed, is_input, 1, maxp));
+		hs_transfers = max(1u, (maxp + 187) / 188);
+		if (is_input) {
+			u32	tmp;
+
+			addr |= 1 << 31;
+			stream->ps.c_usecs = stream->ps.usecs;
+			stream->ps.usecs = HS_USECS_ISO(1);
+			stream->ps.cs_mask = 1;
+
+			/* c-mask as specified in USB 2.0 11.18.4 3.c */
+			tmp = (1 << (hs_transfers + 2)) - 1;
+			stream->ps.cs_mask |= tmp << (8 + 2);
+		} else
+			stream->ps.cs_mask = smask_out[hs_transfers - 1];
+
+		/* period for bandwidth allocation */
+		tmp = min_t(unsigned, EHCI_BANDWIDTH_FRAMES,
+				1 << (urb->ep->desc.bInterval - 1));
+
+		/* Allow urb->interval to override */
+		stream->ps.bw_period = min_t(unsigned, tmp, urb->interval);
+		stream->ps.bw_uperiod = stream->ps.bw_period << 3;
+
+		stream->ps.period = urb->interval;
+		stream->uperiod = urb->interval << 3;
+		stream->bandwidth = (stream->ps.usecs + stream->ps.c_usecs) /
+				stream->ps.bw_period;
+
+		/* stream->splits gets created from cs_mask later */
+		stream->address = cpu_to_hc32(ehci, addr);
+	}
+
+	stream->ps.udev = dev;
+	stream->ps.ep = urb->ep;
+
+	stream->bEndpointAddress = is_input | epnum;
+	stream->maxp = maxp;
+}
+
+static struct ehci_iso_stream *
+iso_stream_find(struct ehci_hcd *ehci, struct urb *urb)
+{
+	unsigned		epnum;
+	struct ehci_iso_stream	*stream;
+	struct usb_host_endpoint *ep;
+	unsigned long		flags;
+
+	epnum = usb_pipeendpoint (urb->pipe);
+	if (usb_pipein(urb->pipe))
+		ep = urb->dev->ep_in[epnum];
+	else
+		ep = urb->dev->ep_out[epnum];
+
+	spin_lock_irqsave(&ehci->lock, flags);
+	stream = ep->hcpriv;
+
+	if (unlikely(stream == NULL)) {
+		stream = iso_stream_alloc(GFP_ATOMIC);
+		if (likely(stream != NULL)) {
+			ep->hcpriv = stream;
+			iso_stream_init(ehci, stream, urb);
+		}
+
+	/* if dev->ep [epnum] is a QH, hw is set */
+	} else if (unlikely(stream->hw != NULL)) {
+		ehci_dbg(ehci, "dev %s ep%d%s, not iso??\n",
+			urb->dev->devpath, epnum,
+			usb_pipein(urb->pipe) ? "in" : "out");
+		stream = NULL;
+	}
+
+	spin_unlock_irqrestore(&ehci->lock, flags);
+	return stream;
+}
+
+/*-------------------------------------------------------------------------*/
+
+/* ehci_iso_sched ops can be ITD-only or SITD-only */
+
+static struct ehci_iso_sched *
+iso_sched_alloc(unsigned packets, gfp_t mem_flags)
+{
+	struct ehci_iso_sched	*iso_sched;
+
+	iso_sched = kzalloc(struct_size(iso_sched, packet, packets), mem_flags);
+	if (likely(iso_sched != NULL))
+		INIT_LIST_HEAD(&iso_sched->td_list);
+
+	return iso_sched;
+}
+
+static inline void
+itd_sched_init(
+	struct ehci_hcd		*ehci,
+	struct ehci_iso_sched	*iso_sched,
+	struct ehci_iso_stream	*stream,
+	struct urb		*urb
+)
+{
+	unsigned	i;
+	dma_addr_t	dma = urb->transfer_dma;
+
+	/* how many uframes are needed for these transfers */
+	iso_sched->span = urb->number_of_packets * stream->uperiod;
+
+	/* figure out per-uframe itd fields that we'll need later
+	 * when we fit new itds into the schedule.
+	 */
+	for (i = 0; i < urb->number_of_packets; i++) {
+		struct ehci_iso_packet	*uframe = &iso_sched->packet[i];
+		unsigned		length;
+		dma_addr_t		buf;
+		u32			trans;
+
+		length = urb->iso_frame_desc[i].length;
+		buf = dma + urb->iso_frame_desc[i].offset;
+
+		trans = EHCI_ISOC_ACTIVE;
+		trans |= buf & 0x0fff;
+		if (unlikely(((i + 1) == urb->number_of_packets))
+				&& !(urb->transfer_flags & URB_NO_INTERRUPT))
+			trans |= EHCI_ITD_IOC;
+		trans |= length << 16;
+		uframe->transaction = cpu_to_hc32(ehci, trans);
+
+		/* might need to cross a buffer page within a uframe */
+		uframe->bufp = (buf & ~(u64)0x0fff);
+		buf += length;
+		if (unlikely((uframe->bufp != (buf & ~(u64)0x0fff))))
+			uframe->cross = 1;
+	}
+}
+
+static void
+iso_sched_free(
+	struct ehci_iso_stream	*stream,
+	struct ehci_iso_sched	*iso_sched
+)
+{
+	if (!iso_sched)
+		return;
+	/* caller must hold ehci->lock! */
+	list_splice(&iso_sched->td_list, &stream->free_list);
+	kfree(iso_sched);
+}
+
+static int
+itd_urb_transaction(
+	struct ehci_iso_stream	*stream,
+	struct ehci_hcd		*ehci,
+	struct urb		*urb,
+	gfp_t			mem_flags
+)
+{
+	struct ehci_itd		*itd;
+	dma_addr_t		itd_dma;
+	int			i;
+	unsigned		num_itds;
+	struct ehci_iso_sched	*sched;
+	unsigned long		flags;
+
+	sched = iso_sched_alloc(urb->number_of_packets, mem_flags);
+	if (unlikely(sched == NULL))
+		return -ENOMEM;
+
+	itd_sched_init(ehci, sched, stream, urb);
+
+	if (urb->interval < 8)
+		num_itds = 1 + (sched->span + 7) / 8;
+	else
+		num_itds = urb->number_of_packets;
+
+	/* allocate/init ITDs */
+	spin_lock_irqsave(&ehci->lock, flags);
+	for (i = 0; i < num_itds; i++) {
+
+		/*
+		 * Use iTDs from the free list, but not iTDs that may
+		 * still be in use by the hardware.
+		 */
+		if (likely(!list_empty(&stream->free_list))) {
+			itd = list_first_entry(&stream->free_list,
+					struct ehci_itd, itd_list);
+			if (itd->frame == ehci->now_frame)
+				goto alloc_itd;
+			list_del(&itd->itd_list);
+			itd_dma = itd->itd_dma;
+		} else {
+ alloc_itd:
+			spin_unlock_irqrestore(&ehci->lock, flags);
+			itd = dma_pool_alloc(ehci->itd_pool, mem_flags,
+					&itd_dma);
+			spin_lock_irqsave(&ehci->lock, flags);
+			if (!itd) {
+				iso_sched_free(stream, sched);
+				spin_unlock_irqrestore(&ehci->lock, flags);
+				return -ENOMEM;
+			}
+		}
+
+		memset(itd, 0, sizeof(*itd));
+		itd->itd_dma = itd_dma;
+		itd->frame = NO_FRAME;
+		list_add(&itd->itd_list, &sched->td_list);
+	}
+	spin_unlock_irqrestore(&ehci->lock, flags);
+
+	/* temporarily store schedule info in hcpriv */
+	urb->hcpriv = sched;
+	urb->error_count = 0;
+	return 0;
+}
+
+/*-------------------------------------------------------------------------*/
+
+static void reserve_release_iso_bandwidth(struct ehci_hcd *ehci,
+		struct ehci_iso_stream *stream, int sign)
+{
+	unsigned		uframe;
+	unsigned		i, j;
+	unsigned		s_mask, c_mask, m;
+	int			usecs = stream->ps.usecs;
+	int			c_usecs = stream->ps.c_usecs;
+	int			tt_usecs = stream->ps.tt_usecs;
+	struct ehci_tt		*tt;
+
+	if (stream->ps.phase == NO_FRAME)	/* Bandwidth wasn't reserved */
+		return;
+	uframe = stream->ps.bw_phase << 3;
+
+	bandwidth_dbg(ehci, sign, "iso", &stream->ps);
+
+	if (sign < 0) {		/* Release bandwidth */
+		usecs = -usecs;
+		c_usecs = -c_usecs;
+		tt_usecs = -tt_usecs;
+	}
+
+	if (!stream->splits) {		/* High speed */
+		for (i = uframe + stream->ps.phase_uf; i < EHCI_BANDWIDTH_SIZE;
+				i += stream->ps.bw_uperiod)
+			ehci->bandwidth[i] += usecs;
+
+	} else {			/* Full speed */
+		s_mask = stream->ps.cs_mask;
+		c_mask = s_mask >> 8;
+
+		/* NOTE: adjustment needed for frame overflow */
+		for (i = uframe; i < EHCI_BANDWIDTH_SIZE;
+				i += stream->ps.bw_uperiod) {
+			for ((j = stream->ps.phase_uf, m = 1 << j); j < 8;
+					(++j, m <<= 1)) {
+				if (s_mask & m)
+					ehci->bandwidth[i+j] += usecs;
+				else if (c_mask & m)
+					ehci->bandwidth[i+j] += c_usecs;
+			}
+		}
+
+		/*
+		 * find_tt() will not return any error here as we have
+		 * already called find_tt() before calling this function
+		 * and checked for any error return. The previous call
+		 * would have created the data structure.
+		 */
+		tt = find_tt(stream->ps.udev);
+		if (sign > 0)
+			list_add_tail(&stream->ps.ps_list, &tt->ps_list);
+		else
+			list_del(&stream->ps.ps_list);
+
+		for (i = uframe >> 3; i < EHCI_BANDWIDTH_FRAMES;
+				i += stream->ps.bw_period)
+			tt->bandwidth[i] += tt_usecs;
+	}
+}
+
+static inline int
+itd_slot_ok(
+	struct ehci_hcd		*ehci,
+	struct ehci_iso_stream	*stream,
+	unsigned		uframe
+)
+{
+	unsigned		usecs;
+
+	/* convert "usecs we need" to "max already claimed" */
+	usecs = ehci->uframe_periodic_max - stream->ps.usecs;
+
+	for (uframe &= stream->ps.bw_uperiod - 1; uframe < EHCI_BANDWIDTH_SIZE;
+			uframe += stream->ps.bw_uperiod) {
+		if (ehci->bandwidth[uframe] > usecs)
+			return 0;
+	}
+	return 1;
+}
+
+static inline int
+sitd_slot_ok(
+	struct ehci_hcd		*ehci,
+	struct ehci_iso_stream	*stream,
+	unsigned		uframe,
+	struct ehci_iso_sched	*sched,
+	struct ehci_tt		*tt
+)
+{
+	unsigned		mask, tmp;
+	unsigned		frame, uf;
+
+	mask = stream->ps.cs_mask << (uframe & 7);
+
+	/* for OUT, don't wrap SSPLIT into H-microframe 7 */
+	if (((stream->ps.cs_mask & 0xff) << (uframe & 7)) >= (1 << 7))
+		return 0;
+
+	/* for IN, don't wrap CSPLIT into the next frame */
+	if (mask & ~0xffff)
+		return 0;
+
+	/* check bandwidth */
+	uframe &= stream->ps.bw_uperiod - 1;
+	frame = uframe >> 3;
+
+#ifdef CONFIG_USB_EHCI_TT_NEWSCHED
+	/* The tt's fullspeed bus bandwidth must be available.
+	 * tt_available scheduling guarantees 10+% for control/bulk.
+	 */
+	uf = uframe & 7;
+	if (!tt_available(ehci, &stream->ps, tt, frame, uf))
+		return 0;
+#else
+	/* tt must be idle for start(s), any gap, and csplit.
+	 * assume scheduling slop leaves 10+% for control/bulk.
+	 */
+	if (!tt_no_collision(ehci, stream->ps.bw_period,
+			stream->ps.udev, frame, mask))
+		return 0;
+#endif
+
+	do {
+		unsigned	max_used;
+		unsigned	i;
+
+		/* check starts (OUT uses more than one) */
+		uf = uframe;
+		max_used = ehci->uframe_periodic_max - stream->ps.usecs;
+		for (tmp = stream->ps.cs_mask & 0xff; tmp; tmp >>= 1, uf++) {
+			if (ehci->bandwidth[uf] > max_used)
+				return 0;
+		}
+
+		/* for IN, check CSPLIT */
+		if (stream->ps.c_usecs) {
+			max_used = ehci->uframe_periodic_max -
+					stream->ps.c_usecs;
+			uf = uframe & ~7;
+			tmp = 1 << (2+8);
+			for (i = (uframe & 7) + 2; i < 8; (++i, tmp <<= 1)) {
+				if ((stream->ps.cs_mask & tmp) == 0)
+					continue;
+				if (ehci->bandwidth[uf+i] > max_used)
+					return 0;
+			}
+		}
+
+		uframe += stream->ps.bw_uperiod;
+	} while (uframe < EHCI_BANDWIDTH_SIZE);
+
+	stream->ps.cs_mask <<= uframe & 7;
+	stream->splits = cpu_to_hc32(ehci, stream->ps.cs_mask);
+	return 1;
+}
+
+/*
+ * This scheduler plans almost as far into the future as it has actual
+ * periodic schedule slots.  (Affected by TUNE_FLS, which defaults to
+ * "as small as possible" to be cache-friendlier.)  That limits the size
+ * transfers you can stream reliably; avoid more than 64 msec per urb.
+ * Also avoid queue depths of less than ehci's worst irq latency (affected
+ * by the per-urb URB_NO_INTERRUPT hint, the log2_irq_thresh module parameter,
+ * and other factors); or more than about 230 msec total (for portability,
+ * given EHCI_TUNE_FLS and the slop).  Or, write a smarter scheduler!
+ */
+
+static int
+iso_stream_schedule(
+	struct ehci_hcd		*ehci,
+	struct urb		*urb,
+	struct ehci_iso_stream	*stream
+)
+{
+	u32			now, base, next, start, period, span, now2;
+	u32			wrap = 0, skip = 0;
+	int			status = 0;
+	unsigned		mod = ehci->periodic_size << 3;
+	struct ehci_iso_sched	*sched = urb->hcpriv;
+	bool			empty = list_empty(&stream->td_list);
+	bool			new_stream = false;
+
+	period = stream->uperiod;
+	span = sched->span;
+	if (!stream->highspeed)
+		span <<= 3;
+
+	/* Start a new isochronous stream? */
+	if (unlikely(empty && !hcd_periodic_completion_in_progress(
+			ehci_to_hcd(ehci), urb->ep))) {
+
+		/* Schedule the endpoint */
+		if (stream->ps.phase == NO_FRAME) {
+			int		done = 0;
+			struct ehci_tt	*tt = find_tt(stream->ps.udev);
+
+			if (IS_ERR(tt)) {
+				status = PTR_ERR(tt);
+				goto fail;
+			}
+			compute_tt_budget(ehci->tt_budget, tt);
+
+			start = ((-(++ehci->random_frame)) << 3) & (period - 1);
+
+			/* find a uframe slot with enough bandwidth.
+			 * Early uframes are more precious because full-speed
+			 * iso IN transfers can't use late uframes,
+			 * and therefore they should be allocated last.
+			 */
+			next = start;
+			start += period;
+			do {
+				start--;
+				/* check schedule: enough space? */
+				if (stream->highspeed) {
+					if (itd_slot_ok(ehci, stream, start))
+						done = 1;
+				} else {
+					if ((start % 8) >= 6)
+						continue;
+					if (sitd_slot_ok(ehci, stream, start,
+							sched, tt))
+						done = 1;
+				}
+			} while (start > next && !done);
+
+			/* no room in the schedule */
+			if (!done) {
+				ehci_dbg(ehci, "iso sched full %p", urb);
+				status = -ENOSPC;
+				goto fail;
+			}
+			stream->ps.phase = (start >> 3) &
+					(stream->ps.period - 1);
+			stream->ps.bw_phase = stream->ps.phase &
+					(stream->ps.bw_period - 1);
+			stream->ps.phase_uf = start & 7;
+			reserve_release_iso_bandwidth(ehci, stream, 1);
+		}
+
+		/* New stream is already scheduled; use the upcoming slot */
+		else {
+			start = (stream->ps.phase << 3) + stream->ps.phase_uf;
+		}
+
+		stream->next_uframe = start;
+		new_stream = true;
+	}
+
+	now = ehci_read_frame_index(ehci) & (mod - 1);
+
+	/* Take the isochronous scheduling threshold into account */
+	if (ehci->i_thresh)
+		next = now + ehci->i_thresh;	/* uframe cache */
+	else
+		next = (now + 2 + 7) & ~0x07;	/* full frame cache */
+
+	/* If needed, initialize last_iso_frame so that this URB will be seen */
+	if (ehci->isoc_count == 0)
+		ehci->last_iso_frame = now >> 3;
+
+	/*
+	 * Use ehci->last_iso_frame as the base.  There can't be any
+	 * TDs scheduled for earlier than that.
+	 */
+	base = ehci->last_iso_frame << 3;
+	next = (next - base) & (mod - 1);
+	start = (stream->next_uframe - base) & (mod - 1);
+
+	if (unlikely(new_stream))
+		goto do_ASAP;
+
+	/*
+	 * Typical case: reuse current schedule, stream may still be active.
+	 * Hopefully there are no gaps from the host falling behind
+	 * (irq delays etc).  If there are, the behavior depends on
+	 * whether URB_ISO_ASAP is set.
+	 */
+	now2 = (now - base) & (mod - 1);
+
+	/* Is the schedule about to wrap around? */
+	if (unlikely(!empty && start < period)) {
+		ehci_dbg(ehci, "request %p would overflow (%u-%u < %u mod %u)\n",
+				urb, stream->next_uframe, base, period, mod);
+		status = -EFBIG;
+		goto fail;
+	}
+
+	/* Is the next packet scheduled after the base time? */
+	if (likely(!empty || start <= now2 + period)) {
+
+		/* URB_ISO_ASAP: make sure that start >= next */
+		if (unlikely(start < next &&
+				(urb->transfer_flags & URB_ISO_ASAP)))
+			goto do_ASAP;
+
+		/* Otherwise use start, if it's not in the past */
+		if (likely(start >= now2))
+			goto use_start;
+
+	/* Otherwise we got an underrun while the queue was empty */
+	} else {
+		if (urb->transfer_flags & URB_ISO_ASAP)
+			goto do_ASAP;
+		wrap = mod;
+		now2 += mod;
+	}
+
+	/* How many uframes and packets do we need to skip? */
+	skip = (now2 - start + period - 1) & -period;
+	if (skip >= span) {		/* Entirely in the past? */
+		ehci_dbg(ehci, "iso underrun %p (%u+%u < %u) [%u]\n",
+				urb, start + base, span - period, now2 + base,
+				base);
+
+		/* Try to keep the last TD intact for scanning later */
+		skip = span - period;
+
+		/* Will it come before the current scan position? */
+		if (empty) {
+			skip = span;	/* Skip the entire URB */
+			status = 1;	/* and give it back immediately */
+			iso_sched_free(stream, sched);
+			sched = NULL;
+		}
+	}
+	urb->error_count = skip / period;
+	if (sched)
+		sched->first_packet = urb->error_count;
+	goto use_start;
+
+ do_ASAP:
+	/* Use the first slot after "next" */
+	start = next + ((start - next) & (period - 1));
+
+ use_start:
+	/* Tried to schedule too far into the future? */
+	if (unlikely(start + span - period >= mod + wrap)) {
+		ehci_dbg(ehci, "request %p would overflow (%u+%u >= %u)\n",
+				urb, start, span - period, mod + wrap);
+		status = -EFBIG;
+		goto fail;
+	}
+
+	start += base;
+	stream->next_uframe = (start + skip) & (mod - 1);
+
+	/* report high speed start in uframes; full speed, in frames */
+	urb->start_frame = start & (mod - 1);
+	if (!stream->highspeed)
+		urb->start_frame >>= 3;
+	return status;
+
+ fail:
+	iso_sched_free(stream, sched);
+	urb->hcpriv = NULL;
+	return status;
+}
+
+/*-------------------------------------------------------------------------*/
+
+static inline void
+itd_init(struct ehci_hcd *ehci, struct ehci_iso_stream *stream,
+		struct ehci_itd *itd)
+{
+	int i;
+
+	/* it's been recently zeroed */
+	itd->hw_next = EHCI_LIST_END(ehci);
+	itd->hw_bufp[0] = stream->buf0;
+	itd->hw_bufp[1] = stream->buf1;
+	itd->hw_bufp[2] = stream->buf2;
+
+	for (i = 0; i < 8; i++)
+		itd->index[i] = -1;
+
+	/* All other fields are filled when scheduling */
+}
+
+static inline void
+itd_patch(
+	struct ehci_hcd		*ehci,
+	struct ehci_itd		*itd,
+	struct ehci_iso_sched	*iso_sched,
+	unsigned		index,
+	u16			uframe
+)
+{
+	struct ehci_iso_packet	*uf = &iso_sched->packet[index];
+	unsigned		pg = itd->pg;
+
+	/* BUG_ON(pg == 6 && uf->cross); */
+
+	uframe &= 0x07;
+	itd->index[uframe] = index;
+
+	itd->hw_transaction[uframe] = uf->transaction;
+	itd->hw_transaction[uframe] |= cpu_to_hc32(ehci, pg << 12);
+	itd->hw_bufp[pg] |= cpu_to_hc32(ehci, uf->bufp & ~(u32)0);
+	itd->hw_bufp_hi[pg] |= cpu_to_hc32(ehci, (u32)(uf->bufp >> 32));
+
+	/* iso_frame_desc[].offset must be strictly increasing */
+	if (unlikely(uf->cross)) {
+		u64	bufp = uf->bufp + 4096;
+
+		itd->pg = ++pg;
+		itd->hw_bufp[pg] |= cpu_to_hc32(ehci, bufp & ~(u32)0);
+		itd->hw_bufp_hi[pg] |= cpu_to_hc32(ehci, (u32)(bufp >> 32));
+	}
+}
+
+static inline void
+itd_link(struct ehci_hcd *ehci, unsigned frame, struct ehci_itd *itd)
+{
+	union ehci_shadow	*prev = &ehci->pshadow[frame];
+	__hc32			*hw_p = &ehci->periodic[frame];
+	union ehci_shadow	here = *prev;
+	__hc32			type = 0;
+
+	/* skip any iso nodes which might belong to previous microframes */
+	while (here.ptr) {
+		type = Q_NEXT_TYPE(ehci, *hw_p);
+		if (type == cpu_to_hc32(ehci, Q_TYPE_QH))
+			break;
+		prev = periodic_next_shadow(ehci, prev, type);
+		hw_p = shadow_next_periodic(ehci, &here, type);
+		here = *prev;
+	}
+
+	itd->itd_next = here;
+	itd->hw_next = *hw_p;
+	prev->itd = itd;
+	itd->frame = frame;
+	wmb();
+	*hw_p = cpu_to_hc32(ehci, itd->itd_dma | Q_TYPE_ITD);
+}
+
+/* fit urb's itds into the selected schedule slot; activate as needed */
+static void itd_link_urb(
+	struct ehci_hcd		*ehci,
+	struct urb		*urb,
+	unsigned		mod,
+	struct ehci_iso_stream	*stream
+)
+{
+	int			packet;
+	unsigned		next_uframe, uframe, frame;
+	struct ehci_iso_sched	*iso_sched = urb->hcpriv;
+	struct ehci_itd		*itd;
+
+	next_uframe = stream->next_uframe & (mod - 1);
+
+	if (unlikely(list_empty(&stream->td_list)))
+		ehci_to_hcd(ehci)->self.bandwidth_allocated
+				+= stream->bandwidth;
+
+	if (ehci_to_hcd(ehci)->self.bandwidth_isoc_reqs == 0) {
+		if (ehci->amd_pll_fix == 1)
+			usb_amd_quirk_pll_disable();
+	}
+
+	ehci_to_hcd(ehci)->self.bandwidth_isoc_reqs++;
+
+	/* fill iTDs uframe by uframe */
+	for (packet = iso_sched->first_packet, itd = NULL;
+			packet < urb->number_of_packets;) {
+		if (itd == NULL) {
+			/* ASSERT:  we have all necessary itds */
+			/* BUG_ON(list_empty(&iso_sched->td_list)); */
+
+			/* ASSERT:  no itds for this endpoint in this uframe */
+
+			itd = list_entry(iso_sched->td_list.next,
+					struct ehci_itd, itd_list);
+			list_move_tail(&itd->itd_list, &stream->td_list);
+			itd->stream = stream;
+			itd->urb = urb;
+			itd_init(ehci, stream, itd);
+		}
+
+		uframe = next_uframe & 0x07;
+		frame = next_uframe >> 3;
+
+		itd_patch(ehci, itd, iso_sched, packet, uframe);
+
+		next_uframe += stream->uperiod;
+		next_uframe &= mod - 1;
+		packet++;
+
+		/* link completed itds into the schedule */
+		if (((next_uframe >> 3) != frame)
+				|| packet == urb->number_of_packets) {
+			itd_link(ehci, frame & (ehci->periodic_size - 1), itd);
+			itd = NULL;
+		}
+	}
+	stream->next_uframe = next_uframe;
+
+	/* don't need that schedule data any more */
+	iso_sched_free(stream, iso_sched);
+	urb->hcpriv = stream;
+
+	++ehci->isoc_count;
+	enable_periodic(ehci);
+}
+
+#define	ISO_ERRS (EHCI_ISOC_BUF_ERR | EHCI_ISOC_BABBLE | EHCI_ISOC_XACTERR)
+
+/* Process and recycle a completed ITD.  Return true iff its urb completed,
+ * and hence its completion callback probably added things to the hardware
+ * schedule.
+ *
+ * Note that we carefully avoid recycling this descriptor until after any
+ * completion callback runs, so that it won't be reused quickly.  That is,
+ * assuming (a) no more than two urbs per frame on this endpoint, and also
+ * (b) only this endpoint's completions submit URBs.  It seems some silicon
+ * corrupts things if you reuse completed descriptors very quickly...
+ */
+static bool itd_complete(struct ehci_hcd *ehci, struct ehci_itd *itd)
+{
+	struct urb				*urb = itd->urb;
+	struct usb_iso_packet_descriptor	*desc;
+	u32					t;
+	unsigned				uframe;
+	int					urb_index = -1;
+	struct ehci_iso_stream			*stream = itd->stream;
+	bool					retval = false;
+
+	/* for each uframe with a packet */
+	for (uframe = 0; uframe < 8; uframe++) {
+		if (likely(itd->index[uframe] == -1))
+			continue;
+		urb_index = itd->index[uframe];
+		desc = &urb->iso_frame_desc[urb_index];
+
+		t = hc32_to_cpup(ehci, &itd->hw_transaction[uframe]);
+		itd->hw_transaction[uframe] = 0;
+
+		/* report transfer status */
+		if (unlikely(t & ISO_ERRS)) {
+			urb->error_count++;
+			if (t & EHCI_ISOC_BUF_ERR)
+				desc->status = usb_pipein(urb->pipe)
+					? -ENOSR  /* hc couldn't read */
+					: -ECOMM; /* hc couldn't write */
+			else if (t & EHCI_ISOC_BABBLE)
+				desc->status = -EOVERFLOW;
+			else /* (t & EHCI_ISOC_XACTERR) */
+				desc->status = -EPROTO;
+
+			/* HC need not update length with this error */
+			if (!(t & EHCI_ISOC_BABBLE)) {
+				desc->actual_length = EHCI_ITD_LENGTH(t);
+				urb->actual_length += desc->actual_length;
+			}
+		} else if (likely((t & EHCI_ISOC_ACTIVE) == 0)) {
+			desc->status = 0;
+			desc->actual_length = EHCI_ITD_LENGTH(t);
+			urb->actual_length += desc->actual_length;
+		} else {
+			/* URB was too late */
+			urb->error_count++;
+		}
+	}
+
+	/* handle completion now? */
+	if (likely((urb_index + 1) != urb->number_of_packets))
+		goto done;
+
+	/*
+	 * ASSERT: it's really the last itd for this urb
+	 * list_for_each_entry (itd, &stream->td_list, itd_list)
+	 *	 BUG_ON(itd->urb == urb);
+	 */
+
+	/* give urb back to the driver; completion often (re)submits */
+	ehci_urb_done(ehci, urb, 0);
+	retval = true;
+	urb = NULL;
+
+	--ehci->isoc_count;
+	disable_periodic(ehci);
+
+	ehci_to_hcd(ehci)->self.bandwidth_isoc_reqs--;
+	if (ehci_to_hcd(ehci)->self.bandwidth_isoc_reqs == 0) {
+		if (ehci->amd_pll_fix == 1)
+			usb_amd_quirk_pll_enable();
+	}
+
+	if (unlikely(list_is_singular(&stream->td_list)))
+		ehci_to_hcd(ehci)->self.bandwidth_allocated
+				-= stream->bandwidth;
+
+done:
+	itd->urb = NULL;
+
+	/* Add to the end of the free list for later reuse */
+	list_move_tail(&itd->itd_list, &stream->free_list);
+
+	/* Recycle the iTDs when the pipeline is empty (ep no longer in use) */
+	if (list_empty(&stream->td_list)) {
+		list_splice_tail_init(&stream->free_list,
+				&ehci->cached_itd_list);
+		start_free_itds(ehci);
+	}
+
+	return retval;
+}
+
+/*-------------------------------------------------------------------------*/
+
+static int itd_submit(struct ehci_hcd *ehci, struct urb *urb,
+	gfp_t mem_flags)
+{
+	int			status = -EINVAL;
+	unsigned long		flags;
+	struct ehci_iso_stream	*stream;
+
+	/* Get iso_stream head */
+	stream = iso_stream_find(ehci, urb);
+	if (unlikely(stream == NULL)) {
+		ehci_dbg(ehci, "can't get iso stream\n");
+		return -ENOMEM;
+	}
+	if (unlikely(urb->interval != stream->uperiod)) {
+		ehci_dbg(ehci, "can't change iso interval %d --> %d\n",
+			stream->uperiod, urb->interval);
+		goto done;
+	}
+
+#ifdef EHCI_URB_TRACE
+	ehci_dbg(ehci,
+		"%s %s urb %p ep%d%s len %d, %d pkts %d uframes [%p]\n",
+		__func__, urb->dev->devpath, urb,
+		usb_pipeendpoint(urb->pipe),
+		usb_pipein(urb->pipe) ? "in" : "out",
+		urb->transfer_buffer_length,
+		urb->number_of_packets, urb->interval,
+		stream);
+#endif
+
+	/* allocate ITDs w/o locking anything */
+	status = itd_urb_transaction(stream, ehci, urb, mem_flags);
+	if (unlikely(status < 0)) {
+		ehci_dbg(ehci, "can't init itds\n");
+		goto done;
+	}
+
+	/* schedule ... need to lock */
+	spin_lock_irqsave(&ehci->lock, flags);
+	if (unlikely(!HCD_HW_ACCESSIBLE(ehci_to_hcd(ehci)))) {
+		status = -ESHUTDOWN;
+		goto done_not_linked;
+	}
+	status = usb_hcd_link_urb_to_ep(ehci_to_hcd(ehci), urb);
+	if (unlikely(status))
+		goto done_not_linked;
+	status = iso_stream_schedule(ehci, urb, stream);
+	if (likely(status == 0)) {
+		itd_link_urb(ehci, urb, ehci->periodic_size << 3, stream);
+	} else if (status > 0) {
+		status = 0;
+		ehci_urb_done(ehci, urb, 0);
+	} else {
+		usb_hcd_unlink_urb_from_ep(ehci_to_hcd(ehci), urb);
+	}
+ done_not_linked:
+	spin_unlock_irqrestore(&ehci->lock, flags);
+ done:
+	return status;
+}
+
+/*-------------------------------------------------------------------------*/
+
+/*
+ * "Split ISO TDs" ... used for USB 1.1 devices going through the
+ * TTs in USB 2.0 hubs.  These need microframe scheduling.
+ */
+
+static inline void
+sitd_sched_init(
+	struct ehci_hcd		*ehci,
+	struct ehci_iso_sched	*iso_sched,
+	struct ehci_iso_stream	*stream,
+	struct urb		*urb
+)
+{
+	unsigned	i;
+	dma_addr_t	dma = urb->transfer_dma;
+
+	/* how many frames are needed for these transfers */
+	iso_sched->span = urb->number_of_packets * stream->ps.period;
+
+	/* figure out per-frame sitd fields that we'll need later
+	 * when we fit new sitds into the schedule.
+	 */
+	for (i = 0; i < urb->number_of_packets; i++) {
+		struct ehci_iso_packet	*packet = &iso_sched->packet[i];
+		unsigned		length;
+		dma_addr_t		buf;
+		u32			trans;
+
+		length = urb->iso_frame_desc[i].length & 0x03ff;
+		buf = dma + urb->iso_frame_desc[i].offset;
+
+		trans = SITD_STS_ACTIVE;
+		if (((i + 1) == urb->number_of_packets)
+				&& !(urb->transfer_flags & URB_NO_INTERRUPT))
+			trans |= SITD_IOC;
+		trans |= length << 16;
+		packet->transaction = cpu_to_hc32(ehci, trans);
+
+		/* might need to cross a buffer page within a td */
+		packet->bufp = buf;
+		packet->buf1 = (buf + length) & ~0x0fff;
+		if (packet->buf1 != (buf & ~(u64)0x0fff))
+			packet->cross = 1;
+
+		/* OUT uses multiple start-splits */
+		if (stream->bEndpointAddress & USB_DIR_IN)
+			continue;
+		length = (length + 187) / 188;
+		if (length > 1) /* BEGIN vs ALL */
+			length |= 1 << 3;
+		packet->buf1 |= length;
+	}
+}
+
+static int
+sitd_urb_transaction(
+	struct ehci_iso_stream	*stream,
+	struct ehci_hcd		*ehci,
+	struct urb		*urb,
+	gfp_t			mem_flags
+)
+{
+	struct ehci_sitd	*sitd;
+	dma_addr_t		sitd_dma;
+	int			i;
+	struct ehci_iso_sched	*iso_sched;
+	unsigned long		flags;
+
+	iso_sched = iso_sched_alloc(urb->number_of_packets, mem_flags);
+	if (iso_sched == NULL)
+		return -ENOMEM;
+
+	sitd_sched_init(ehci, iso_sched, stream, urb);
+
+	/* allocate/init sITDs */
+	spin_lock_irqsave(&ehci->lock, flags);
+	for (i = 0; i < urb->number_of_packets; i++) {
+
+		/* NOTE:  for now, we don't try to handle wraparound cases
+		 * for IN (using sitd->hw_backpointer, like a FSTN), which
+		 * means we never need two sitds for full speed packets.
+		 */
+
+		/*
+		 * Use siTDs from the free list, but not siTDs that may
+		 * still be in use by the hardware.
+		 */
+		if (likely(!list_empty(&stream->free_list))) {
+			sitd = list_first_entry(&stream->free_list,
+					 struct ehci_sitd, sitd_list);
+			if (sitd->frame == ehci->now_frame)
+				goto alloc_sitd;
+			list_del(&sitd->sitd_list);
+			sitd_dma = sitd->sitd_dma;
+		} else {
+ alloc_sitd:
+			spin_unlock_irqrestore(&ehci->lock, flags);
+			sitd = dma_pool_alloc(ehci->sitd_pool, mem_flags,
+					&sitd_dma);
+			spin_lock_irqsave(&ehci->lock, flags);
+			if (!sitd) {
+				iso_sched_free(stream, iso_sched);
+				spin_unlock_irqrestore(&ehci->lock, flags);
+				return -ENOMEM;
+			}
+		}
+
+		memset(sitd, 0, sizeof(*sitd));
+		sitd->sitd_dma = sitd_dma;
+		sitd->frame = NO_FRAME;
+		list_add(&sitd->sitd_list, &iso_sched->td_list);
+	}
+
+	/* temporarily store schedule info in hcpriv */
+	urb->hcpriv = iso_sched;
+	urb->error_count = 0;
+
+	spin_unlock_irqrestore(&ehci->lock, flags);
+	return 0;
+}
+
+/*-------------------------------------------------------------------------*/
+
+static inline void
+sitd_patch(
+	struct ehci_hcd		*ehci,
+	struct ehci_iso_stream	*stream,
+	struct ehci_sitd	*sitd,
+	struct ehci_iso_sched	*iso_sched,
+	unsigned		index
+)
+{
+	struct ehci_iso_packet	*uf = &iso_sched->packet[index];
+	u64			bufp;
+
+	sitd->hw_next = EHCI_LIST_END(ehci);
+	sitd->hw_fullspeed_ep = stream->address;
+	sitd->hw_uframe = stream->splits;
+	sitd->hw_results = uf->transaction;
+	sitd->hw_backpointer = EHCI_LIST_END(ehci);
+
+	bufp = uf->bufp;
+	sitd->hw_buf[0] = cpu_to_hc32(ehci, bufp);
+	sitd->hw_buf_hi[0] = cpu_to_hc32(ehci, bufp >> 32);
+
+	sitd->hw_buf[1] = cpu_to_hc32(ehci, uf->buf1);
+	if (uf->cross)
+		bufp += 4096;
+	sitd->hw_buf_hi[1] = cpu_to_hc32(ehci, bufp >> 32);
+	sitd->index = index;
+}
+
+static inline void
+sitd_link(struct ehci_hcd *ehci, unsigned frame, struct ehci_sitd *sitd)
+{
+	/* note: sitd ordering could matter (CSPLIT then SSPLIT) */
+	sitd->sitd_next = ehci->pshadow[frame];
+	sitd->hw_next = ehci->periodic[frame];
+	ehci->pshadow[frame].sitd = sitd;
+	sitd->frame = frame;
+	wmb();
+	ehci->periodic[frame] = cpu_to_hc32(ehci, sitd->sitd_dma | Q_TYPE_SITD);
+}
+
+/* fit urb's sitds into the selected schedule slot; activate as needed */
+static void sitd_link_urb(
+	struct ehci_hcd		*ehci,
+	struct urb		*urb,
+	unsigned		mod,
+	struct ehci_iso_stream	*stream
+)
+{
+	int			packet;
+	unsigned		next_uframe;
+	struct ehci_iso_sched	*sched = urb->hcpriv;
+	struct ehci_sitd	*sitd;
+
+	next_uframe = stream->next_uframe;
+
+	if (list_empty(&stream->td_list))
+		/* usbfs ignores TT bandwidth */
+		ehci_to_hcd(ehci)->self.bandwidth_allocated
+				+= stream->bandwidth;
+
+	if (ehci_to_hcd(ehci)->self.bandwidth_isoc_reqs == 0) {
+		if (ehci->amd_pll_fix == 1)
+			usb_amd_quirk_pll_disable();
+	}
+
+	ehci_to_hcd(ehci)->self.bandwidth_isoc_reqs++;
+
+	/* fill sITDs frame by frame */
+	for (packet = sched->first_packet, sitd = NULL;
+			packet < urb->number_of_packets;
+			packet++) {
+
+		/* ASSERT:  we have all necessary sitds */
+		BUG_ON(list_empty(&sched->td_list));
+
+		/* ASSERT:  no itds for this endpoint in this frame */
+
+		sitd = list_entry(sched->td_list.next,
+				struct ehci_sitd, sitd_list);
+		list_move_tail(&sitd->sitd_list, &stream->td_list);
+		sitd->stream = stream;
+		sitd->urb = urb;
+
+		sitd_patch(ehci, stream, sitd, sched, packet);
+		sitd_link(ehci, (next_uframe >> 3) & (ehci->periodic_size - 1),
+				sitd);
+
+		next_uframe += stream->uperiod;
+	}
+	stream->next_uframe = next_uframe & (mod - 1);
+
+	/* don't need that schedule data any more */
+	iso_sched_free(stream, sched);
+	urb->hcpriv = stream;
+
+	++ehci->isoc_count;
+	enable_periodic(ehci);
+}
+
+/*-------------------------------------------------------------------------*/
+
+#define	SITD_ERRS (SITD_STS_ERR | SITD_STS_DBE | SITD_STS_BABBLE \
+				| SITD_STS_XACT | SITD_STS_MMF)
+
+/* Process and recycle a completed SITD.  Return true iff its urb completed,
+ * and hence its completion callback probably added things to the hardware
+ * schedule.
+ *
+ * Note that we carefully avoid recycling this descriptor until after any
+ * completion callback runs, so that it won't be reused quickly.  That is,
+ * assuming (a) no more than two urbs per frame on this endpoint, and also
+ * (b) only this endpoint's completions submit URBs.  It seems some silicon
+ * corrupts things if you reuse completed descriptors very quickly...
+ */
+static bool sitd_complete(struct ehci_hcd *ehci, struct ehci_sitd *sitd)
+{
+	struct urb				*urb = sitd->urb;
+	struct usb_iso_packet_descriptor	*desc;
+	u32					t;
+	int					urb_index;
+	struct ehci_iso_stream			*stream = sitd->stream;
+	bool					retval = false;
+
+	urb_index = sitd->index;
+	desc = &urb->iso_frame_desc[urb_index];
+	t = hc32_to_cpup(ehci, &sitd->hw_results);
+
+	/* report transfer status */
+	if (unlikely(t & SITD_ERRS)) {
+		urb->error_count++;
+		if (t & SITD_STS_DBE)
+			desc->status = usb_pipein(urb->pipe)
+				? -ENOSR  /* hc couldn't read */
+				: -ECOMM; /* hc couldn't write */
+		else if (t & SITD_STS_BABBLE)
+			desc->status = -EOVERFLOW;
+		else /* XACT, MMF, etc */
+			desc->status = -EPROTO;
+	} else if (unlikely(t & SITD_STS_ACTIVE)) {
+		/* URB was too late */
+		urb->error_count++;
+	} else {
+		desc->status = 0;
+		desc->actual_length = desc->length - SITD_LENGTH(t);
+		urb->actual_length += desc->actual_length;
+	}
+
+	/* handle completion now? */
+	if ((urb_index + 1) != urb->number_of_packets)
+		goto done;
+
+	/*
+	 * ASSERT: it's really the last sitd for this urb
+	 * list_for_each_entry (sitd, &stream->td_list, sitd_list)
+	 *	 BUG_ON(sitd->urb == urb);
+	 */
+
+	/* give urb back to the driver; completion often (re)submits */
+	ehci_urb_done(ehci, urb, 0);
+	retval = true;
+	urb = NULL;
+
+	--ehci->isoc_count;
+	disable_periodic(ehci);
+
+	ehci_to_hcd(ehci)->self.bandwidth_isoc_reqs--;
+	if (ehci_to_hcd(ehci)->self.bandwidth_isoc_reqs == 0) {
+		if (ehci->amd_pll_fix == 1)
+			usb_amd_quirk_pll_enable();
+	}
+
+	if (list_is_singular(&stream->td_list))
+		ehci_to_hcd(ehci)->self.bandwidth_allocated
+				-= stream->bandwidth;
+
+done:
+	sitd->urb = NULL;
+
+	/* Add to the end of the free list for later reuse */
+	list_move_tail(&sitd->sitd_list, &stream->free_list);
+
+	/* Recycle the siTDs when the pipeline is empty (ep no longer in use) */
+	if (list_empty(&stream->td_list)) {
+		list_splice_tail_init(&stream->free_list,
+				&ehci->cached_sitd_list);
+		start_free_itds(ehci);
+	}
+
+	return retval;
+}
+
+
+static int sitd_submit(struct ehci_hcd *ehci, struct urb *urb,
+	gfp_t mem_flags)
+{
+	int			status = -EINVAL;
+	unsigned long		flags;
+	struct ehci_iso_stream	*stream;
+
+	/* Get iso_stream head */
+	stream = iso_stream_find(ehci, urb);
+	if (stream == NULL) {
+		ehci_dbg(ehci, "can't get iso stream\n");
+		return -ENOMEM;
+	}
+	if (urb->interval != stream->ps.period) {
+		ehci_dbg(ehci, "can't change iso interval %d --> %d\n",
+			stream->ps.period, urb->interval);
+		goto done;
+	}
+
+#ifdef EHCI_URB_TRACE
+	ehci_dbg(ehci,
+		"submit %p dev%s ep%d%s-iso len %d\n",
+		urb, urb->dev->devpath,
+		usb_pipeendpoint(urb->pipe),
+		usb_pipein(urb->pipe) ? "in" : "out",
+		urb->transfer_buffer_length);
+#endif
+
+	/* allocate SITDs */
+	status = sitd_urb_transaction(stream, ehci, urb, mem_flags);
+	if (status < 0) {
+		ehci_dbg(ehci, "can't init sitds\n");
+		goto done;
+	}
+
+	/* schedule ... need to lock */
+	spin_lock_irqsave(&ehci->lock, flags);
+	if (unlikely(!HCD_HW_ACCESSIBLE(ehci_to_hcd(ehci)))) {
+		status = -ESHUTDOWN;
+		goto done_not_linked;
+	}
+	status = usb_hcd_link_urb_to_ep(ehci_to_hcd(ehci), urb);
+	if (unlikely(status))
+		goto done_not_linked;
+	status = iso_stream_schedule(ehci, urb, stream);
+	if (likely(status == 0)) {
+		sitd_link_urb(ehci, urb, ehci->periodic_size << 3, stream);
+	} else if (status > 0) {
+		status = 0;
+		ehci_urb_done(ehci, urb, 0);
+	} else {
+		usb_hcd_unlink_urb_from_ep(ehci_to_hcd(ehci), urb);
+	}
+ done_not_linked:
+	spin_unlock_irqrestore(&ehci->lock, flags);
+ done:
+	return status;
+}
+
+/*-------------------------------------------------------------------------*/
+
+static void scan_isoc(struct ehci_hcd *ehci)
+{
+	unsigned		uf, now_frame, frame;
+	unsigned		fmask = ehci->periodic_size - 1;
+	bool			modified, live;
+	union ehci_shadow	q, *q_p;
+	__hc32			type, *hw_p;
+
+	/*
+	 * When running, scan from last scan point up to "now"
+	 * else clean up by scanning everything that's left.
+	 * Touches as few pages as possible:  cache-friendly.
+	 */
+	if (ehci->rh_state >= EHCI_RH_RUNNING) {
+		uf = ehci_read_frame_index(ehci);
+		now_frame = (uf >> 3) & fmask;
+		live = true;
+	} else  {
+		now_frame = (ehci->last_iso_frame - 1) & fmask;
+		live = false;
+	}
+	ehci->now_frame = now_frame;
+
+	frame = ehci->last_iso_frame;
+
+restart:
+	/* Scan each element in frame's queue for completions */
+	q_p = &ehci->pshadow[frame];
+	hw_p = &ehci->periodic[frame];
+	q.ptr = q_p->ptr;
+	type = Q_NEXT_TYPE(ehci, *hw_p);
+	modified = false;
+
+	while (q.ptr != NULL) {
+		switch (hc32_to_cpu(ehci, type)) {
+		case Q_TYPE_ITD:
+			/*
+			 * If this ITD is still active, leave it for
+			 * later processing ... check the next entry.
+			 * No need to check for activity unless the
+			 * frame is current.
+			 */
+			if (frame == now_frame && live) {
+				rmb();
+				for (uf = 0; uf < 8; uf++) {
+					if (q.itd->hw_transaction[uf] &
+							ITD_ACTIVE(ehci))
+						break;
+				}
+				if (uf < 8) {
+					q_p = &q.itd->itd_next;
+					hw_p = &q.itd->hw_next;
+					type = Q_NEXT_TYPE(ehci,
+							q.itd->hw_next);
+					q = *q_p;
+					break;
+				}
+			}
+
+			/*
+			 * Take finished ITDs out of the schedule
+			 * and process them:  recycle, maybe report
+			 * URB completion.  HC won't cache the
+			 * pointer for much longer, if at all.
+			 */
+			*q_p = q.itd->itd_next;
+			if (!ehci->use_dummy_qh ||
+					q.itd->hw_next != EHCI_LIST_END(ehci))
+				*hw_p = q.itd->hw_next;
+			else
+				*hw_p = cpu_to_hc32(ehci, ehci->dummy->qh_dma);
+			type = Q_NEXT_TYPE(ehci, q.itd->hw_next);
+			wmb();
+			modified = itd_complete(ehci, q.itd);
+			q = *q_p;
+			break;
+		case Q_TYPE_SITD:
+			/*
+			 * If this SITD is still active, leave it for
+			 * later processing ... check the next entry.
+			 * No need to check for activity unless the
+			 * frame is current.
+			 */
+			if (((frame == now_frame) ||
+					(((frame + 1) & fmask) == now_frame))
+				&& live
+				&& (q.sitd->hw_results & SITD_ACTIVE(ehci))) {
+
+				q_p = &q.sitd->sitd_next;
+				hw_p = &q.sitd->hw_next;
+				type = Q_NEXT_TYPE(ehci, q.sitd->hw_next);
+				q = *q_p;
+				break;
+			}
+
+			/*
+			 * Take finished SITDs out of the schedule
+			 * and process them:  recycle, maybe report
+			 * URB completion.
+			 */
+			*q_p = q.sitd->sitd_next;
+			if (!ehci->use_dummy_qh ||
+					q.sitd->hw_next != EHCI_LIST_END(ehci))
+				*hw_p = q.sitd->hw_next;
+			else
+				*hw_p = cpu_to_hc32(ehci, ehci->dummy->qh_dma);
+			type = Q_NEXT_TYPE(ehci, q.sitd->hw_next);
+			wmb();
+			modified = sitd_complete(ehci, q.sitd);
+			q = *q_p;
+			break;
+		default:
+			ehci_dbg(ehci, "corrupt type %d frame %d shadow %p\n",
+					type, frame, q.ptr);
+			/* BUG(); */
+			fallthrough;
+		case Q_TYPE_QH:
+		case Q_TYPE_FSTN:
+			/* End of the iTDs and siTDs */
+			q.ptr = NULL;
+			break;
+		}
+
+		/* Assume completion callbacks modify the queue */
+		if (unlikely(modified && ehci->isoc_count > 0))
+			goto restart;
+	}
+
+	/* Stop when we have reached the current frame */
+	if (frame == now_frame)
+		return;
+
+	/* The last frame may still have active siTDs */
+	ehci->last_iso_frame = frame;
+	frame = (frame + 1) & fmask;
+
+	goto restart;
+}