usb/isp1760: Improve urb queueing, get rid of BUG():s in normal code paths

This patch replaces the code that handles qtds. Intead of directly allocating
chip mem and chip slot, enqueue the transfer in a list of queue heads. Use
a centralized function enqueue_qtds() to prioritize and enqueue transfers.

This removes all of the interrupt context BUG() calls when out of chip
mem or transfer slots. It also makes it possible to efficiently use the
dual-port mem on the chip for double-buffered transfers, which improve
transfer times to/from/between usb sticks by about 40 % on my HW.

With this patch it should also be possible to handle qtd scheduling outside
of the interrupt handler, for significantly improved kernel latency. I have
not implemented this since there are some locking issues which I haven't
had time to look at.

Signed-off-by: Arvid Brodin <arvid.brodin@enea.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

2 files changed, 679 insertions, 699 deletions

diff --git a/drivers/usb/host/isp1760-hcd.c b/drivers/usb/host/isp1760-hcd.c
index b38cfe98f226..dd98a966b58b 100644
--- a/drivers/usb/host/isp1760-hcd.c
+++ b/drivers/usb/host/isp1760-hcd.c
@@ -8,6 +8,8 @@
  *
  * (c) 2007 Sebastian Siewior <bigeasy@linutronix.de>
  *
+ * (c) 2011 Arvid Brodin <arvid.brodin@enea.com>
+ *
  */
 #include <linux/module.h>
 #include <linux/kernel.h>
@@ -26,14 +28,16 @@
 
 static struct kmem_cache *qtd_cachep;
 static struct kmem_cache *qh_cachep;
+static struct kmem_cache *urb_listitem_cachep;
 
 struct isp1760_hcd {
 	u32 hcs_params;
 	spinlock_t		lock;
-	struct inter_packet_info atl_ints[32];
-	struct inter_packet_info int_ints[32];
+	struct slotinfo		atl_slots[32];
+	struct slotinfo		int_slots[32];
 	struct memory_chunk memory_pool[BLOCKS];
-	u32 atl_queued;
+	struct list_head	controlqhs, bulkqhs, interruptqhs;
+	int active_ptds;
 
 	/* periodic schedule support */
 #define	DEFAULT_I_TDPS		1024
@@ -85,18 +89,34 @@ struct isp1760_qtd {
 	struct list_head qtd_list;
 	struct urb *urb;
 	size_t length;
-
-	/* isp special*/
+	size_t actual_length;
+
+	/* QTD_ENQUEUED:	waiting for transfer (inactive) */
+	/* QTD_PAYLOAD_ALLOC:	chip mem has been allocated for payload */
+	/* QTD_XFER_STARTED:	valid ptd has been written to isp176x - only
+				interrupt handler may touch this qtd! */
+	/* QTD_XFER_COMPLETE:	payload has been transferred successfully */
+	/* QTD_RETIRE:		transfer error/abort qtd */
+#define QTD_ENQUEUED		0
+#define QTD_PAYLOAD_ALLOC	1
+#define QTD_XFER_STARTED	2
+#define QTD_XFER_COMPLETE	3
+#define QTD_RETIRE		4
 	u32 status;
-#define URB_ENQUEUED		(1 << 1)
 };
 
+/* Queue head, one for each active endpoint */
 struct isp1760_qh {
-	/* first part defined by EHCI spec */
+	struct list_head qh_list;
 	struct list_head qtd_list;
-
 	u32 toggle;
 	u32 ping;
+	int slot;
+};
+
+struct urb_listitem {
+	struct list_head urb_list;
+	struct urb *urb;
 };
 
 /*
@@ -293,19 +313,6 @@ static void alloc_mem(struct usb_hcd *hcd, struct isp1760_qtd *qtd)
 			return;
 		}
 	}
-
-	dev_err(hcd->self.controller,
-				"%s: Cannot allocate %zu bytes of memory\n"
-				"Current memory map:\n",
-				__func__, qtd->length);
-	for (i = 0; i < BLOCKS; i++) {
-		dev_err(hcd->self.controller, "Pool %2d size %4d status: %d\n",
-				i, priv->memory_pool[i].size,
-				priv->memory_pool[i].free);
-	}
-	/* XXX maybe -ENOMEM could be possible */
-	BUG();
-	return;
 }
 
 static void free_mem(struct usb_hcd *hcd, struct isp1760_qtd *qtd)
@@ -327,15 +334,8 @@ static void free_mem(struct usb_hcd *hcd, struct isp1760_qtd *qtd)
 
 	dev_err(hcd->self.controller, "%s: Invalid pointer: %08x\n",
 						__func__, qtd->payload_addr);
-	BUG();
-}
-
-static void isp1760_init_regs(struct usb_hcd *hcd)
-{
-	reg_write32(hcd->regs, HC_BUFFER_STATUS_REG, 0);
-	reg_write32(hcd->regs, HC_ATL_PTD_SKIPMAP_REG, NO_TRANSFER_ACTIVE);
-	reg_write32(hcd->regs, HC_INT_PTD_SKIPMAP_REG, NO_TRANSFER_ACTIVE);
-	reg_write32(hcd->regs, HC_ISO_PTD_SKIPMAP_REG, NO_TRANSFER_ACTIVE);
+	WARN_ON(1);
+	qtd->payload_addr = 0;
 }
 
 static int handshake(struct usb_hcd *hcd, u32 reg,
@@ -373,31 +373,27 @@ static int ehci_reset(struct usb_hcd *hcd)
 	return retval;
 }
 
-static void qh_destroy(struct isp1760_qh *qh)
-{
-	WARN_ON(!list_empty(&qh->qtd_list));
-	kmem_cache_free(qh_cachep, qh);
-}
-
-static struct isp1760_qh *isp1760_qh_alloc(gfp_t flags)
+static struct isp1760_qh *qh_alloc(gfp_t flags)
 {
 	struct isp1760_qh *qh;
 
 	qh = kmem_cache_zalloc(qh_cachep, flags);
 	if (!qh)
-		return qh;
+		return NULL;
 
+	INIT_LIST_HEAD(&qh->qh_list);
 	INIT_LIST_HEAD(&qh->qtd_list);
+	qh->slot = -1;
+
 	return qh;
 }
 
-/* magic numbers that can affect system performance */
-#define	EHCI_TUNE_CERR		3	/* 0-3 qtd retries; 0 == don't stop */
-#define	EHCI_TUNE_RL_HS		4	/* nak throttle; see 4.9 */
-#define	EHCI_TUNE_RL_TT		0
-#define	EHCI_TUNE_MULT_HS	1	/* 1-3 transactions/uframe; 4.10.3 */
-#define	EHCI_TUNE_MULT_TT	1
-#define	EHCI_TUNE_FLS		2	/* (small) 256 frame schedule */
+static void qh_free(struct isp1760_qh *qh)
+{
+	WARN_ON(!list_empty(&qh->qtd_list));
+	WARN_ON(qh->slot > -1);
+	kmem_cache_free(qh_cachep, qh);
+}
 
 /* one-time init, only for memory state */
 static int priv_init(struct usb_hcd *hcd)
@@ -407,6 +403,10 @@ static int priv_init(struct usb_hcd *hcd)
 
 	spin_lock_init(&priv->lock);
 
+	INIT_LIST_HEAD(&priv->interruptqhs);
+	INIT_LIST_HEAD(&priv->controlqhs);
+	INIT_LIST_HEAD(&priv->bulkqhs);
+
 	/*
 	 * hw default: 1K periodic list heads, one per frame.
 	 * periodic_size can shrink by USBCMD update if hcc_params allows.
@@ -464,7 +464,10 @@ static int isp1760_hc_setup(struct usb_hcd *hcd)
 	}
 
 	/* pre reset */
-	isp1760_init_regs(hcd);
+	reg_write32(hcd->regs, HC_BUFFER_STATUS_REG, 0);
+	reg_write32(hcd->regs, HC_ATL_PTD_SKIPMAP_REG, NO_TRANSFER_ACTIVE);
+	reg_write32(hcd->regs, HC_INT_PTD_SKIPMAP_REG, NO_TRANSFER_ACTIVE);
+	reg_write32(hcd->regs, HC_ISO_PTD_SKIPMAP_REG, NO_TRANSFER_ACTIVE);
 
 	/* reset */
 	reg_write32(hcd->regs, HC_RESET_REG, SW_RESET_RESET_ALL);
@@ -484,12 +487,15 @@ static int isp1760_hc_setup(struct usb_hcd *hcd)
 			   16 : 32, (priv->devflags & ISP1760_FLAG_ANALOG_OC) ?
 			   "analog" : "digital");
 
+	/* This is weird: at the first plug-in of a device there seems to be
+	   one packet queued that never gets returned? */
+	priv->active_ptds = -1;
+
 	/* ATL reset */
 	reg_write32(hcd->regs, HC_HW_MODE_CTRL, hwmode | ALL_ATX_RESET);
 	mdelay(10);
 	reg_write32(hcd->regs, HC_HW_MODE_CTRL, hwmode);
 
-	reg_write32(hcd->regs, HC_INTERRUPT_REG, INTERRUPT_ENABLE_MASK);
 	reg_write32(hcd->regs, HC_INTERRUPT_ENABLE, INTERRUPT_ENABLE_MASK);
 
 	/*
@@ -513,6 +519,10 @@ static void isp1760_init_maps(struct usb_hcd *hcd)
 	reg_write32(hcd->regs, HC_INT_PTD_LASTPTD_REG, 0x80000000);
 	reg_write32(hcd->regs, HC_ISO_PTD_LASTPTD_REG, 0x00000001);
 
+	reg_write32(hcd->regs, HC_ATL_PTD_SKIPMAP_REG, 0);
+	reg_write32(hcd->regs, HC_INT_PTD_SKIPMAP_REG, 0);
+	reg_write32(hcd->regs, HC_ISO_PTD_SKIPMAP_REG, 0);
+
 	reg_write32(hcd->regs, HC_BUFFER_STATUS_REG,
 						ATL_BUF_FILL | INT_BUF_FILL);
 }
@@ -547,8 +557,7 @@ static int isp1760_run(struct usb_hcd *hcd)
 	command |= CMD_RUN;
 	reg_write32(hcd->regs, HC_USBCMD, command);
 
-	retval = handshake(hcd, HC_USBCMD, CMD_RUN, CMD_RUN,
-			250 * 1000);
+	retval = handshake(hcd, HC_USBCMD, CMD_RUN, CMD_RUN, 250 * 1000);
 	if (retval)
 		return retval;
 
@@ -597,12 +606,19 @@ static int last_qtd_of_urb(struct isp1760_qtd *qtd, struct isp1760_qh *qh)
 	return (qtd->urb != urb);
 }
 
-static void transform_into_atl(struct isp1760_qh *qh,
+/* magic numbers that can affect system performance */
+#define	EHCI_TUNE_CERR		3	/* 0-3 qtd retries; 0 == don't stop */
+#define	EHCI_TUNE_RL_HS		4	/* nak throttle; see 4.9 */
+#define	EHCI_TUNE_RL_TT		0
+#define	EHCI_TUNE_MULT_HS	1	/* 1-3 transactions/uframe; 4.10.3 */
+#define	EHCI_TUNE_MULT_TT	1
+#define	EHCI_TUNE_FLS		2	/* (small) 256 frame schedule */
+
+static void create_ptd_atl(struct isp1760_qh *qh,
 			struct isp1760_qtd *qtd, struct ptd *ptd)
 {
 	u32 maxpacket;
 	u32 multi;
-	u32 pid_code;
 	u32 rl = RL_COUNTER;
 	u32 nak = NAK_COUNTER;
 
@@ -615,67 +631,62 @@ static void transform_into_atl(struct isp1760_qh *qh,
 	maxpacket &= 0x7ff;
 
 	/* DW0 */
-	ptd->dw0 = PTD_VALID;
-	ptd->dw0 |= PTD_LENGTH(qtd->length);
-	ptd->dw0 |= PTD_MAXPACKET(maxpacket);
-	ptd->dw0 |= PTD_ENDPOINT(usb_pipeendpoint(qtd->urb->pipe));
+	ptd->dw0 = DW0_VALID_BIT;
+	ptd->dw0 |= TO_DW0_LENGTH(qtd->length);
+	ptd->dw0 |= TO_DW0_MAXPACKET(maxpacket);
+	ptd->dw0 |= TO_DW0_ENDPOINT(usb_pipeendpoint(qtd->urb->pipe));
 
 	/* DW1 */
 	ptd->dw1 = usb_pipeendpoint(qtd->urb->pipe) >> 1;
-	ptd->dw1 |= PTD_DEVICE_ADDR(usb_pipedevice(qtd->urb->pipe));
-
-	pid_code = qtd->packet_type;
-	ptd->dw1 |= PTD_PID_TOKEN(pid_code);
+	ptd->dw1 |= TO_DW1_DEVICE_ADDR(usb_pipedevice(qtd->urb->pipe));
+	ptd->dw1 |= TO_DW1_PID_TOKEN(qtd->packet_type);
 
 	if (usb_pipebulk(qtd->urb->pipe))
-		ptd->dw1 |= PTD_TRANS_BULK;
+		ptd->dw1 |= DW1_TRANS_BULK;
 	else if  (usb_pipeint(qtd->urb->pipe))
-		ptd->dw1 |= PTD_TRANS_INT;
+		ptd->dw1 |= DW1_TRANS_INT;
 
 	if (qtd->urb->dev->speed != USB_SPEED_HIGH) {
 		/* split transaction */
 
-		ptd->dw1 |= PTD_TRANS_SPLIT;
+		ptd->dw1 |= DW1_TRANS_SPLIT;
 		if (qtd->urb->dev->speed == USB_SPEED_LOW)
-			ptd->dw1 |= PTD_SE_USB_LOSPEED;
+			ptd->dw1 |= DW1_SE_USB_LOSPEED;
 
-		ptd->dw1 |= PTD_PORT_NUM(qtd->urb->dev->ttport);
-		ptd->dw1 |= PTD_HUB_NUM(qtd->urb->dev->tt->hub->devnum);
+		ptd->dw1 |= TO_DW1_PORT_NUM(qtd->urb->dev->ttport);
+		ptd->dw1 |= TO_DW1_HUB_NUM(qtd->urb->dev->tt->hub->devnum);
 
 		/* SE bit for Split INT transfers */
 		if (usb_pipeint(qtd->urb->pipe) &&
 				(qtd->urb->dev->speed == USB_SPEED_LOW))
 			ptd->dw1 |= 2 << 16;
 
-		ptd->dw3 = 0;
 		rl = 0;
 		nak = 0;
 	} else {
-		ptd->dw0 |= PTD_MULTI(multi);
+		ptd->dw0 |= TO_DW0_MULTI(multi);
 		if (usb_pipecontrol(qtd->urb->pipe) ||
 						usb_pipebulk(qtd->urb->pipe))
-			ptd->dw3 = qh->ping;
-		else
-			ptd->dw3 = 0;
+			ptd->dw3 |= TO_DW3_PING(qh->ping);
 	}
 	/* DW2 */
 	ptd->dw2 = 0;
-	ptd->dw2 |= PTD_DATA_START_ADDR(base_to_chip(qtd->payload_addr));
-	ptd->dw2 |= PTD_RL_CNT(rl);
-	ptd->dw3 |= PTD_NAC_CNT(nak);
+	ptd->dw2 |= TO_DW2_DATA_START_ADDR(base_to_chip(qtd->payload_addr));
+	ptd->dw2 |= TO_DW2_RL(rl);
 
 	/* DW3 */
-	ptd->dw3 |= qh->toggle;
+	ptd->dw3 |= TO_DW3_NAKCOUNT(nak);
+	ptd->dw3 |= TO_DW3_DATA_TOGGLE(qh->toggle);
 	if (usb_pipecontrol(qtd->urb->pipe)) {
 		if (qtd->data_buffer == qtd->urb->setup_packet)
-			ptd->dw3 &= ~PTD_DATA_TOGGLE(1);
+			ptd->dw3 &= ~TO_DW3_DATA_TOGGLE(1);
 		else if (last_qtd_of_urb(qtd, qh))
-			ptd->dw3 |= PTD_DATA_TOGGLE(1);
+			ptd->dw3 |= TO_DW3_DATA_TOGGLE(1);
 	}
 
-	ptd->dw3 |= PTD_ACTIVE;
+	ptd->dw3 |= DW3_ACTIVE_BIT;
 	/* Cerr */
-	ptd->dw3 |= PTD_CERR(ERR_COUNTER);
+	ptd->dw3 |= TO_DW3_CERR(ERR_COUNTER);
 }
 
 static void transform_add_int(struct isp1760_qh *qh,
@@ -730,162 +741,13 @@ static void transform_add_int(struct isp1760_qh *qh,
 	ptd->dw4 = usof;
 }
 
-static void transform_into_int(struct isp1760_qh *qh,
+static void create_ptd_int(struct isp1760_qh *qh,
 			struct isp1760_qtd *qtd, struct ptd *ptd)
 {
-	transform_into_atl(qh, qtd, ptd);
+	create_ptd_atl(qh, qtd, ptd);
 	transform_add_int(qh, qtd, ptd);
 }
 
-static int check_error(struct usb_hcd *hcd, struct ptd *ptd)
-{
-	int error = 0;
-
-	if (ptd->dw3 & DW3_HALT_BIT) {
-		error = -EPIPE;
-
-		if (ptd->dw3 & DW3_ERROR_BIT)
-			pr_err("error bit is set in DW3\n");
-	}
-
-	if (ptd->dw3 & DW3_QTD_ACTIVE) {
-		dev_err(hcd->self.controller, "Transfer active bit is set DW3\n"
-			"nak counter: %d, rl: %d\n",
-			(ptd->dw3 >> 19) & 0xf, (ptd->dw2 >> 25) & 0xf);
-	}
-
-	return error;
-}
-
-static void check_int_err_status(struct usb_hcd *hcd, u32 dw4)
-{
-	u32 i;
-
-	dw4 >>= 8;
-
-	for (i = 0; i < 8; i++) {
-		switch (dw4 & 0x7) {
-		case INT_UNDERRUN:
-			dev_err(hcd->self.controller, "Underrun (%d)\n", i);
-			break;
-
-		case INT_EXACT:
-			dev_err(hcd->self.controller,
-						"Transaction error (%d)\n", i);
-			break;
-
-		case INT_BABBLE:
-			dev_err(hcd->self.controller, "Babble error (%d)\n", i);
-			break;
-		}
-		dw4 >>= 3;
-	}
-}
-
-static void enqueue_one_qtd(struct usb_hcd *hcd, struct isp1760_qtd *qtd)
-{
-	if (qtd->length && (qtd->length <= MAX_PAYLOAD_SIZE)) {
-		switch (qtd->packet_type) {
-		case IN_PID:
-			break;
-		case OUT_PID:
-		case SETUP_PID:
-			mem_writes8(hcd->regs, qtd->payload_addr,
-						qtd->data_buffer, qtd->length);
-		}
-	}
-}
-
-static void enqueue_one_atl_qtd(struct usb_hcd *hcd, struct isp1760_qh *qh,
-					u32 slot, struct isp1760_qtd *qtd)
-{
-	struct isp1760_hcd *priv = hcd_to_priv(hcd);
-	struct ptd ptd;
-
-	alloc_mem(hcd, qtd);
-	transform_into_atl(qh, qtd, &ptd);
-	ptd_write(hcd->regs, ATL_PTD_OFFSET, slot, &ptd);
-	enqueue_one_qtd(hcd, qtd);
-
-	priv->atl_ints[slot].qh = qh;
-	priv->atl_ints[slot].qtd = qtd;
-	qtd->status |= URB_ENQUEUED;
-	qtd->status |= slot << 16;
-}
-
-static void enqueue_one_int_qtd(struct usb_hcd *hcd, struct isp1760_qh *qh,
-					u32 slot, struct isp1760_qtd *qtd)
-{
-	struct isp1760_hcd *priv = hcd_to_priv(hcd);
-	struct ptd ptd;
-
-	alloc_mem(hcd, qtd);
-	transform_into_int(qh, qtd, &ptd);
-	ptd_write(hcd->regs, INT_PTD_OFFSET, slot, &ptd);
-	enqueue_one_qtd(hcd, qtd);
-
-	priv->int_ints[slot].qh = qh;
-	priv->int_ints[slot].qtd = qtd;
-	qtd->status |= URB_ENQUEUED;
-	qtd->status |= slot << 16;
-}
-
-static void enqueue_an_ATL_packet(struct usb_hcd *hcd, struct isp1760_qh *qh,
-				  struct isp1760_qtd *qtd)
-{
-	struct isp1760_hcd *priv = hcd_to_priv(hcd);
-	u32 skip_map;
-	u32 slot;
-
-	/*
-	 * When this function is called from the interrupt handler to enqueue
-	 * a follow-up packet, the SKIP register gets written and read back
-	 * almost immediately. With ISP1761, this register requires a delay of
-	 * 195ns between a write and subsequent read (see section 15.1.1.3).
-	 */
-	mmiowb();
-	ndelay(195);
-	skip_map = reg_read32(hcd->regs, HC_ATL_PTD_SKIPMAP_REG);
-
-	BUG_ON(!skip_map);
-	slot = __ffs(skip_map);
-
-	enqueue_one_atl_qtd(hcd, qh, slot, qtd);
-
-	skip_map &= ~(1 << slot);
-	reg_write32(hcd->regs, HC_ATL_PTD_SKIPMAP_REG, skip_map);
-
-	priv->atl_queued++;
-	if (priv->atl_queued == 2)
-		reg_write32(hcd->regs, HC_INTERRUPT_ENABLE,
-				INTERRUPT_ENABLE_SOT_MASK);
-}
-
-static void enqueue_an_INT_packet(struct usb_hcd *hcd, struct isp1760_qh *qh,
-				  struct isp1760_qtd *qtd)
-{
-	u32 skip_map;
-	u32 slot;
-
-	/*
-	 * When this function is called from the interrupt handler to enqueue
-	 * a follow-up packet, the SKIP register gets written and read back
-	 * almost immediately. With ISP1761, this register requires a delay of
-	 * 195ns between a write and subsequent read (see section 15.1.1.3).
-	 */
-	mmiowb();
-	ndelay(195);
-	skip_map = reg_read32(hcd->regs, HC_INT_PTD_SKIPMAP_REG);
-
-	BUG_ON(!skip_map);
-	slot = __ffs(skip_map);
-
-	enqueue_one_int_qtd(hcd, qh, slot, qtd);
-
-	skip_map &= ~(1 << slot);
-	reg_write32(hcd->regs, HC_INT_PTD_SKIPMAP_REG, skip_map);
-}
-
 static void isp1760_urb_done(struct usb_hcd *hcd, struct urb *urb)
 __releases(priv->lock)
 __acquires(priv->lock)
@@ -924,6 +786,8 @@ static struct isp1760_qtd *qtd_alloc(gfp_t flags, struct urb *urb,
 	INIT_LIST_HEAD(&qtd->qtd_list);
 	qtd->urb = urb;
 	qtd->packet_type = packet_type;
+	qtd->status = QTD_ENQUEUED;
+	qtd->actual_length = 0;
 
 	return qtd;
 }
@@ -934,323 +798,505 @@ static void qtd_free(struct isp1760_qtd *qtd)
 	kmem_cache_free(qtd_cachep, qtd);
 }
 
-static struct isp1760_qtd *clean_this_qtd(struct isp1760_qtd *qtd,
-							struct isp1760_qh *qh)
+static void start_bus_transfer(struct usb_hcd *hcd, u32 ptd_offset, int slot,
+				struct slotinfo *slots, struct isp1760_qtd *qtd,
+				struct isp1760_qh *qh, struct ptd *ptd)
 {
-	struct isp1760_qtd *tmp_qtd;
-
-	if (list_is_last(&qtd->qtd_list, &qh->qtd_list))
-		tmp_qtd = NULL;
-	else
-		tmp_qtd = list_entry(qtd->qtd_list.next, struct isp1760_qtd,
-								qtd_list);
-	list_del(&qtd->qtd_list);
-	qtd_free(qtd);
-	return tmp_qtd;
+	struct isp1760_hcd *priv = hcd_to_priv(hcd);
+	WARN_ON((slot < 0) || (slot > 31));
+	WARN_ON(qtd->length && !qtd->payload_addr);
+	WARN_ON(slots[slot].qtd);
+	WARN_ON(slots[slot].qh);
+	WARN_ON(qtd->status != QTD_PAYLOAD_ALLOC);
+
+	slots[slot].qtd = qtd;
+	slots[slot].qh = qh;
+	qh->slot = slot;
+	qtd->status = QTD_XFER_STARTED; /* Set this before writing ptd, since
+		interrupt routine may preempt and expects this value. */
+	ptd_write(hcd->regs, ptd_offset, slot, ptd);
+	priv->active_ptds++;
 }
 
-/*
- * Remove this QTD from the QH list and free its memory. If this QTD
- * isn't the last one than remove also his successor(s).
- * Returns the QTD which is part of an new URB and should be enqueued.
- */
-static struct isp1760_qtd *clean_up_qtdlist(struct isp1760_qtd *qtd,
-							struct isp1760_qh *qh)
+static int is_short_bulk(struct isp1760_qtd *qtd)
 {
-	struct urb *urb;
-
-	urb = qtd->urb;
-	do {
-		qtd = clean_this_qtd(qtd, qh);
-	} while (qtd && (qtd->urb == urb));
-
-	return qtd;
+	return (usb_pipebulk(qtd->urb->pipe) &&
+					(qtd->actual_length < qtd->length));
 }
 
-static void do_atl_int(struct usb_hcd *hcd)
+static void collect_qtds(struct usb_hcd *hcd, struct isp1760_qh *qh,
+						struct list_head *urb_list)
 {
-	struct isp1760_hcd *priv = hcd_to_priv(hcd);
-	u32 done_map, skip_map;
-	struct ptd ptd;
-	struct urb *urb;
-	u32 slot;
-	u32 length;
-	u32 status = -EINVAL;
-	int error;
-	struct isp1760_qtd *qtd;
-	struct isp1760_qh *qh;
-	u32 rl;
-	u32 nakcount;
+	int last_qtd;
+	struct isp1760_qtd *qtd, *qtd_next;
+	struct urb_listitem *urb_listitem;
 
-	done_map = reg_read32(hcd->regs, HC_ATL_PTD_DONEMAP_REG);
-	skip_map = reg_read32(hcd->regs, HC_ATL_PTD_SKIPMAP_REG);
+	list_for_each_entry_safe(qtd, qtd_next, &qh->qtd_list, qtd_list) {
+		if (qtd->status < QTD_XFER_COMPLETE)
+			break;
 
-	while (done_map) {
-		status = 0;
-		priv->atl_queued--;
+		if (list_is_last(&qtd->qtd_list, &qh->qtd_list))
+			last_qtd = 1;
+		else
+			last_qtd = qtd->urb != qtd_next->urb;
+
+		if ((!last_qtd) && (qtd->status == QTD_RETIRE))
+			qtd_next->status = QTD_RETIRE;
+
+		if (qtd->status == QTD_XFER_COMPLETE) {
+			if (qtd->actual_length) {
+				switch (qtd->packet_type) {
+				case IN_PID:
+					mem_reads8(hcd->regs, qtd->payload_addr,
+							qtd->data_buffer,
+							qtd->actual_length);
+					/* Fall through (?) */
+				case OUT_PID:
+					qtd->urb->actual_length +=
+							qtd->actual_length;
+					/* Fall through ... */
+				case SETUP_PID:
+					break;
+				}
+			}
 
-		slot = __ffs(done_map);
-		done_map &= ~(1 << slot);
-		skip_map |= (1 << slot);
+			if (is_short_bulk(qtd)) {
+				if (qtd->urb->transfer_flags & URB_SHORT_NOT_OK)
+					qtd->urb->status = -EREMOTEIO;
+				if (!last_qtd)
+					qtd_next->status = QTD_RETIRE;
+			}
+		}
 
-		qtd = priv->atl_ints[slot].qtd;
-		qh = priv->atl_ints[slot].qh;
+		if (qtd->payload_addr)
+			free_mem(hcd, qtd);
 
-		/* urb unlinked? */
-		if (!qh)
-			continue;
+		if (last_qtd) {
+			if ((qtd->status == QTD_RETIRE) &&
+					(qtd->urb->status == -EINPROGRESS))
+				qtd->urb->status = -EPIPE;
+			/* Defer calling of urb_done() since it releases lock */
+			urb_listitem = kmem_cache_zalloc(urb_listitem_cachep,
+								GFP_ATOMIC);
+			if (unlikely(!urb_listitem))
+				break;
+			urb_listitem->urb = qtd->urb;
+			list_add_tail(&urb_listitem->urb_list, urb_list);
+		}
 
-		ptd_read(hcd->regs, ATL_PTD_OFFSET, slot, &ptd);
+		list_del(&qtd->qtd_list);
+		qtd_free(qtd);
+	}
+}
 
-		rl = (ptd.dw2 >> 25) & 0x0f;
-		nakcount = (ptd.dw3 >> 19) & 0xf;
+#define ENQUEUE_DEPTH	2
+static void enqueue_qtds(struct usb_hcd *hcd, struct isp1760_qh *qh)
+{
+	struct isp1760_hcd *priv = hcd_to_priv(hcd);
+	int ptd_offset;
+	struct slotinfo *slots;
+	int curr_slot, free_slot;
+	int n;
+	struct ptd ptd;
+	struct isp1760_qtd *qtd;
 
-		/* Transfer Error, *but* active and no HALT -> reload */
-		if ((ptd.dw3 & DW3_ERROR_BIT) && (ptd.dw3 & DW3_QTD_ACTIVE) &&
-				!(ptd.dw3 & DW3_HALT_BIT)) {
-
-			/* according to ppriv code, we have to
-			 * reload this one if trasfered bytes != requested bytes
-			 * else act like everything went smooth..
-			 * XXX This just doesn't feel right and hasn't
-			 * triggered so far.
-			 */
+	if (unlikely(list_empty(&qh->qtd_list))) {
+		WARN_ON(1);
+		return;
+	}
 
-			length = PTD_XFERRED_LENGTH(ptd.dw3);
-			dev_err(hcd->self.controller,
-					"Should reload now... transferred %d "
-					"of %zu\n", length, qtd->length);
-			BUG();
-		}
+	if (usb_pipeint(list_entry(qh->qtd_list.next, struct isp1760_qtd,
+							qtd_list)->urb->pipe)) {
+		ptd_offset = INT_PTD_OFFSET;
+		slots = priv->int_slots;
+	} else {
+		ptd_offset = ATL_PTD_OFFSET;
+		slots = priv->atl_slots;
+	}
 
-		if (!nakcount && (ptd.dw3 & DW3_QTD_ACTIVE)) {
-			/*
-			 * NAKs are handled in HW by the chip. Usually if the
-			 * device is not able to send data fast enough.
-			 * This happens mostly on slower hardware.
-			 */
+	free_slot = -1;
+	for (curr_slot = 0; curr_slot < 32; curr_slot++) {
+		if ((free_slot == -1) && (slots[curr_slot].qtd == NULL))
+			free_slot = curr_slot;
+		if (slots[curr_slot].qh == qh)
+			break;
+	}
 
-			/* RL counter = ERR counter */
-			ptd.dw3 &= ~(0xf << 19);
-			ptd.dw3 |= rl << 19;
-			ptd.dw3 &= ~(3 << (55 - 32));
-			ptd.dw3 |= ERR_COUNTER << (55 - 32);
-
-			/*
-			 * It is not needed to write skip map back because it
-			 * is unchanged. Just make sure that this entry is
-			 * unskipped once it gets written to the HW.
-			 */
-			skip_map &= ~(1 << slot);
+	n = 0;
+	list_for_each_entry(qtd, &qh->qtd_list, qtd_list) {
+		if (qtd->status == QTD_ENQUEUED) {
+			WARN_ON(qtd->payload_addr);
+			alloc_mem(hcd, qtd);
+			if ((qtd->length) && (!qtd->payload_addr))
+				break;
 
-			ptd.dw0 |= PTD_VALID;
-			ptd_write(hcd->regs, ATL_PTD_OFFSET, slot, &ptd);
+			if ((qtd->length) &&
+			    ((qtd->packet_type == SETUP_PID) ||
+			     (qtd->packet_type == OUT_PID))) {
+				mem_writes8(hcd->regs, qtd->payload_addr,
+						qtd->data_buffer, qtd->length);
+			}
 
-			priv->atl_queued++;
-			if (priv->atl_queued == 2)
-				reg_write32(hcd->regs, HC_INTERRUPT_ENABLE,
-						INTERRUPT_ENABLE_SOT_MASK);
-			continue;
+			qtd->status = QTD_PAYLOAD_ALLOC;
 		}
 
-		error = check_error(hcd, &ptd);
-		if (error) {
-			status = error;
-			priv->atl_ints[slot].qh->toggle = 0;
-			priv->atl_ints[slot].qh->ping = 0;
-			qtd->urb->status = -EPIPE;
-
-#if 0
-			printk(KERN_ERR "Error in %s().\n", __func__);
-			printk(KERN_ERR "IN dw0: %08x dw1: %08x dw2: %08x "
-					"dw3: %08x dw4: %08x dw5: %08x dw6: "
-					"%08x dw7: %08x\n",
-					ptd.dw0, ptd.dw1, ptd.dw2, ptd.dw3,
-					ptd.dw4, ptd.dw5, ptd.dw6, ptd.dw7);
-#endif
-		} else {
-			priv->atl_ints[slot].qh->toggle = ptd.dw3 & (1 << 25);
-			priv->atl_ints[slot].qh->ping = ptd.dw3 & (1 << 26);
+		if (qtd->status == QTD_PAYLOAD_ALLOC) {
+/*
+			if ((curr_slot > 31) && (free_slot == -1))
+				dev_dbg(hcd->self.controller, "%s: No slot "
+					"available for transfer\n", __func__);
+*/
+			/* Start xfer for this endpoint if not already done */
+			if ((curr_slot > 31) && (free_slot > -1)) {
+				if (usb_pipeint(qtd->urb->pipe))
+					create_ptd_int(qh, qtd, &ptd);
+				else
+					create_ptd_atl(qh, qtd, &ptd);
+
+				start_bus_transfer(hcd, ptd_offset, free_slot,
+							slots, qtd, qh, &ptd);
+				curr_slot = free_slot;
+			}
+
+			n++;
+			if (n >= ENQUEUE_DEPTH)
+				break;
 		}
+	}
+}
 
-		length = PTD_XFERRED_LENGTH(ptd.dw3);
-		if (length) {
-			switch (DW1_GET_PID(ptd.dw1)) {
-			case IN_PID:
-				mem_reads8(hcd->regs, qtd->payload_addr,
-						qtd->data_buffer, length);
+void schedule_ptds(struct usb_hcd *hcd)
+{
+	struct isp1760_hcd *priv;
+	struct isp1760_qh *qh, *qh_next;
+	struct list_head *ep_queue;
+	struct usb_host_endpoint *ep;
+	LIST_HEAD(urb_list);
+	struct urb_listitem *urb_listitem, *urb_listitem_next;
 
-			case OUT_PID:
+	if (!hcd) {
+		WARN_ON(1);
+		return;
+	}
 
-				qtd->urb->actual_length += length;
+	priv = hcd_to_priv(hcd);
 
-			case SETUP_PID:
-				break;
+	/*
+	 * check finished/retired xfers, transfer payloads, call urb_done()
+	 */
+	ep_queue = &priv->interruptqhs;
+	while (ep_queue) {
+		list_for_each_entry_safe(qh, qh_next, ep_queue, qh_list) {
+			ep = list_entry(qh->qtd_list.next, struct isp1760_qtd,
+							qtd_list)->urb->ep;
+			collect_qtds(hcd, qh, &urb_list);
+			if (list_empty(&qh->qtd_list)) {
+				list_del(&qh->qh_list);
+				if (ep->hcpriv == NULL) {
+					/* Endpoint has been disabled, so we
+					can free the associated queue head. */
+					qh_free(qh);
+				}
 			}
 		}
 
-		priv->atl_ints[slot].qtd = NULL;
-		priv->atl_ints[slot].qh = NULL;
-
-		free_mem(hcd, qtd);
+		if (ep_queue == &priv->interruptqhs)
+			ep_queue = &priv->controlqhs;
+		else if (ep_queue == &priv->controlqhs)
+			ep_queue = &priv->bulkqhs;
+		else
+			ep_queue = NULL;
+	}
 
-		reg_write32(hcd->regs, HC_ATL_PTD_SKIPMAP_REG, skip_map);
+	list_for_each_entry_safe(urb_listitem, urb_listitem_next, &urb_list,
+								urb_list) {
+		isp1760_urb_done(hcd, urb_listitem->urb);
+		kmem_cache_free(urb_listitem_cachep, urb_listitem);
+	}
 
-		if (qtd->urb->status == -EPIPE) {
-			/* HALT was received */
+	/*
+	 * Schedule packets for transfer.
+	 *
+	 * According to USB2.0 specification:
+	 *
+	 * 1st prio: interrupt xfers, up to 80 % of bandwidth
+	 * 2nd prio: control xfers
+	 * 3rd prio: bulk xfers
+	 *
+	 * ... but let's use a simpler scheme here (mostly because ISP1761 doc
+	 * is very unclear on how to prioritize traffic):
+	 *
+	 * 1) Enqueue any queued control transfers, as long as payload chip mem
+	 *    and PTD ATL slots are available.
+	 * 2) Enqueue any queued INT transfers, as long as payload chip mem
+	 *    and PTD INT slots are available.
+	 * 3) Enqueue any queued bulk transfers, as long as payload chip mem
+	 *    and PTD ATL slots are available.
+	 *
+	 * Use double buffering (ENQUEUE_DEPTH==2) as a compromise between
+	 * conservation of chip mem and performance.
+	 *
+	 * I'm sure this scheme could be improved upon!
+	 */
+	ep_queue = &priv->controlqhs;
+	while (ep_queue) {
+		list_for_each_entry_safe(qh, qh_next, ep_queue, qh_list)
+			enqueue_qtds(hcd, qh);
+
+		if (ep_queue == &priv->controlqhs)
+			ep_queue = &priv->interruptqhs;
+		else if (ep_queue == &priv->interruptqhs)
+			ep_queue = &priv->bulkqhs;
+		else
+			ep_queue = NULL;
+	}
+}
 
-			urb = qtd->urb;
-			qtd = clean_up_qtdlist(qtd, qh);
-			isp1760_urb_done(hcd, urb);
+#define PTD_STATE_QTD_DONE	1
+#define PTD_STATE_QTD_RELOAD	2
+#define PTD_STATE_URB_RETIRE	3
 
-		} else if (usb_pipebulk(qtd->urb->pipe) &&
-						(length < qtd->length)) {
-			/* short BULK received */
+static int check_int_transfer(struct usb_hcd *hcd, struct ptd *ptd,
+								struct urb *urb)
+{
+	__dw dw4;
+	int i;
 
-			if (qtd->urb->transfer_flags & URB_SHORT_NOT_OK) {
-				qtd->urb->status = -EREMOTEIO;
-				dev_dbg(hcd->self.controller,
-						"short bulk, %d instead %zu "
-						"with URB_SHORT_NOT_OK flag.\n",
-						length, qtd->length);
-			}
+	dw4 = ptd->dw4;
+	dw4 >>= 8;
 
-			if (qtd->urb->status == -EINPROGRESS)
-				qtd->urb->status = 0;
+	/* FIXME: ISP1761 datasheet does not say what to do with these. Do we
+	   need to handle these errors? Is it done in hardware? */
 
-			urb = qtd->urb;
-			qtd = clean_up_qtdlist(qtd, qh);
-			isp1760_urb_done(hcd, urb);
+	if (ptd->dw3 & DW3_HALT_BIT) {
 
-		} else if (last_qtd_of_urb(qtd, qh)) {
-			/* that was the last qtd of that URB */
+		urb->status = -EPROTO; /* Default unknown error */
 
-			if (qtd->urb->status == -EINPROGRESS)
-				qtd->urb->status = 0;
+		for (i = 0; i < 8; i++) {
+			switch (dw4 & 0x7) {
+			case INT_UNDERRUN:
+				dev_dbg(hcd->self.controller, "%s: underrun "
+						"during uFrame %d\n",
+						__func__, i);
+				urb->status = -ECOMM; /* Could not write data */
+				break;
+			case INT_EXACT:
+				dev_dbg(hcd->self.controller, "%s: transaction "
+						"error during uFrame %d\n",
+						__func__, i);
+				urb->status = -EPROTO; /* timeout, bad CRC, PID
+							  error etc. */
+				break;
+			case INT_BABBLE:
+				dev_dbg(hcd->self.controller, "%s: babble "
+						"error during uFrame %d\n",
+						__func__, i);
+				urb->status = -EOVERFLOW;
+				break;
+			}
+			dw4 >>= 3;
+		}
 
-			urb = qtd->urb;
-			qtd = clean_up_qtdlist(qtd, qh);
-			isp1760_urb_done(hcd, urb);
+		return PTD_STATE_URB_RETIRE;
+	}
 
-		} else {
-			/* next QTD of this URB */
+	return PTD_STATE_QTD_DONE;
+}
 
-			qtd = clean_this_qtd(qtd, qh);
-			BUG_ON(!qtd);
-		}
+static int check_atl_transfer(struct usb_hcd *hcd, struct ptd *ptd,
+								struct urb *urb)
+{
+	WARN_ON(!ptd);
+	if (ptd->dw3 & DW3_HALT_BIT) {
+		if (ptd->dw3 & DW3_BABBLE_BIT)
+			urb->status = -EOVERFLOW;
+		else if (FROM_DW3_CERR(ptd->dw3))
+			urb->status = -EPIPE;  /* Stall */
+		else if (ptd->dw3 & DW3_ERROR_BIT)
+			urb->status = -EPROTO; /* XactErr */
+		else
+			urb->status = -EPROTO; /* Unknown */
+/*
+		dev_dbg(hcd->self.controller, "%s: ptd error:\n"
+			"        dw0: %08x dw1: %08x dw2: %08x dw3: %08x\n"
+			"        dw4: %08x dw5: %08x dw6: %08x dw7: %08x\n",
+			__func__,
+			ptd->dw0, ptd->dw1, ptd->dw2, ptd->dw3,
+			ptd->dw4, ptd->dw5, ptd->dw6, ptd->dw7);
+*/
+		return PTD_STATE_URB_RETIRE;
+	}
 
-		if (qtd)
-			enqueue_an_ATL_packet(hcd, qh, qtd);
+	if ((ptd->dw3 & DW3_ERROR_BIT) && (ptd->dw3 & DW3_ACTIVE_BIT)) {
+		/* Transfer Error, *but* active and no HALT -> reload */
+		dev_dbg(hcd->self.controller, "PID error; reloading ptd\n");
+		return PTD_STATE_QTD_RELOAD;
+	}
 
-		skip_map = reg_read32(hcd->regs, HC_ATL_PTD_SKIPMAP_REG);
+	if (!FROM_DW3_NAKCOUNT(ptd->dw3) && (ptd->dw3 & DW3_ACTIVE_BIT)) {
+		/*
+		 * NAKs are handled in HW by the chip. Usually if the
+		 * device is not able to send data fast enough.
+		 * This happens mostly on slower hardware.
+		 */
+		return PTD_STATE_QTD_RELOAD;
 	}
-	if (priv->atl_queued <= 1)
-		reg_write32(hcd->regs, HC_INTERRUPT_ENABLE,
-							INTERRUPT_ENABLE_MASK);
+
+	return PTD_STATE_QTD_DONE;
 }
 
-static void do_intl_int(struct usb_hcd *hcd)
+static irqreturn_t isp1760_irq(struct usb_hcd *hcd)
 {
 	struct isp1760_hcd *priv = hcd_to_priv(hcd);
-	u32 done_map, skip_map;
+	u32 imask;
+	irqreturn_t irqret = IRQ_NONE;
 	struct ptd ptd;
-	struct urb *urb;
-	u32 length;
-	int error;
-	u32 slot;
-	struct isp1760_qtd *qtd;
 	struct isp1760_qh *qh;
+	int int_done_map, atl_done_map;
+	int slot;
+	int state;
+	struct slotinfo *slots;
+	u32 ptd_offset;
+	struct isp1760_qtd *qtd;
+	int modified;
+	static int last_active_ptds;
 
-	done_map = reg_read32(hcd->regs, HC_INT_PTD_DONEMAP_REG);
-	skip_map = reg_read32(hcd->regs, HC_INT_PTD_SKIPMAP_REG);
-
-	while (done_map) {
-		slot = __ffs(done_map);
-		done_map &= ~(1 << slot);
-		skip_map |= (1 << slot);
-
-		qtd = priv->int_ints[slot].qtd;
-		qh = priv->int_ints[slot].qh;
-
-		/* urb unlinked? */
-		if (!qh)
-			continue;
+	spin_lock(&priv->lock);
 
-		ptd_read(hcd->regs, INT_PTD_OFFSET, slot, &ptd);
-		check_int_err_status(hcd, ptd.dw4);
-
-		error = check_error(hcd, &ptd);
-		if (error) {
-#if 0
-			printk(KERN_ERR "Error in %s().\n", __func__);
-			printk(KERN_ERR "IN dw0: %08x dw1: %08x dw2: %08x "
-					"dw3: %08x dw4: %08x dw5: %08x dw6: "
-					"%08x dw7: %08x\n",
-					ptd.dw0, ptd.dw1, ptd.dw2, ptd.dw3,
-					ptd.dw4, ptd.dw5, ptd.dw6, ptd.dw7);
-#endif
-			qtd->urb->status = -EPIPE;
-			priv->int_ints[slot].qh->toggle = 0;
-			priv->int_ints[slot].qh->ping = 0;
+	if (!(hcd->state & HC_STATE_RUNNING))
+		goto leave;
 
+	imask = reg_read32(hcd->regs, HC_INTERRUPT_REG);
+	if (unlikely(!imask))
+		goto leave;
+	reg_write32(hcd->regs, HC_INTERRUPT_REG, imask); /* Clear */
+
+	int_done_map = reg_read32(hcd->regs, HC_INT_PTD_DONEMAP_REG);
+	atl_done_map = reg_read32(hcd->regs, HC_ATL_PTD_DONEMAP_REG);
+	modified = int_done_map | atl_done_map;
+
+	while (int_done_map || atl_done_map) {
+		if (int_done_map) {
+			/* INT ptd */
+			slot = __ffs(int_done_map);
+			int_done_map &= ~(1 << slot);
+			slots = priv->int_slots;
+			if (!slots[slot].qh)
+				continue;
+			ptd_offset = INT_PTD_OFFSET;
+			ptd_read(hcd->regs, INT_PTD_OFFSET, slot, &ptd);
+			state = check_int_transfer(hcd, &ptd,
+							slots[slot].qtd->urb);
 		} else {
-			priv->int_ints[slot].qh->toggle = ptd.dw3 & (1 << 25);
-			priv->int_ints[slot].qh->ping = ptd.dw3 & (1 << 26);
+			/* ATL ptd */
+			slot = __ffs(atl_done_map);
+			atl_done_map &= ~(1 << slot);
+			slots = priv->atl_slots;
+			if (!slots[slot].qh)
+				continue;
+			ptd_offset = ATL_PTD_OFFSET;
+			ptd_read(hcd->regs, ATL_PTD_OFFSET, slot, &ptd);
+			state = check_atl_transfer(hcd, &ptd,
+							slots[slot].qtd->urb);
 		}
 
-		if (qtd->urb->dev->speed != USB_SPEED_HIGH)
-			length = PTD_XFERRED_LENGTH_LO(ptd.dw3);
-		else
-			length = PTD_XFERRED_LENGTH(ptd.dw3);
-
-		if (length) {
-			switch (DW1_GET_PID(ptd.dw1)) {
-			case IN_PID:
-				mem_reads8(hcd->regs, qtd->payload_addr,
-						qtd->data_buffer, length);
-			case OUT_PID:
-
-				qtd->urb->actual_length += length;
+		qtd = slots[slot].qtd;
+		slots[slot].qtd = NULL;
+		qh = slots[slot].qh;
+		slots[slot].qh = NULL;
+		priv->active_ptds--;
+		qh->slot = -1;
+
+		WARN_ON(qtd->status != QTD_XFER_STARTED);
+
+		switch (state) {
+		case PTD_STATE_QTD_DONE:
+			if ((usb_pipeint(qtd->urb->pipe)) &&
+				       (qtd->urb->dev->speed != USB_SPEED_HIGH))
+				qtd->actual_length =
+				       FROM_DW3_SCS_NRBYTESTRANSFERRED(ptd.dw3);
+			else
+				qtd->actual_length =
+					FROM_DW3_NRBYTESTRANSFERRED(ptd.dw3);
 
-			case SETUP_PID:
-				break;
-			}
-		}
+			qtd->status = QTD_XFER_COMPLETE;
+			if (list_is_last(&qtd->qtd_list, &qh->qtd_list) ||
+							is_short_bulk(qtd))
+				qtd = NULL;
+			else
+				qtd = list_entry(qtd->qtd_list.next,
+							typeof(*qtd), qtd_list);
 
-		priv->int_ints[slot].qtd = NULL;
-		priv->int_ints[slot].qh = NULL;
+			qh->toggle = FROM_DW3_DATA_TOGGLE(ptd.dw3);
+			qh->ping = FROM_DW3_PING(ptd.dw3);
+			break;
 
-		reg_write32(hcd->regs, HC_INT_PTD_SKIPMAP_REG, skip_map);
-		free_mem(hcd, qtd);
+		case PTD_STATE_QTD_RELOAD: /* QTD_RETRY, for atls only */
+			qtd->status = QTD_PAYLOAD_ALLOC;
+			ptd.dw0 |= DW0_VALID_BIT;
+			/* RL counter = ERR counter */
+			ptd.dw3 &= ~TO_DW3_NAKCOUNT(0xf);
+			ptd.dw3 |= TO_DW3_NAKCOUNT(FROM_DW2_RL(ptd.dw2));
+			ptd.dw3 &= ~TO_DW3_CERR(3);
+			ptd.dw3 |= TO_DW3_CERR(ERR_COUNTER);
+			qh->toggle = FROM_DW3_DATA_TOGGLE(ptd.dw3);
+			qh->ping = FROM_DW3_PING(ptd.dw3);
+			break;
 
-		if (qtd->urb->status == -EPIPE) {
-			/* HALT received */
+		case PTD_STATE_URB_RETIRE:
+			qtd->status = QTD_RETIRE;
+			qtd = NULL;
+			qh->toggle = 0;
+			qh->ping = 0;
+			break;
 
-			urb = qtd->urb;
-			qtd = clean_up_qtdlist(qtd, qh);
-			isp1760_urb_done(hcd, urb);
+		default:
+			WARN_ON(1);
+			continue;
+		}
 
-		} else if (last_qtd_of_urb(qtd, qh)) {
+		if (qtd && (qtd->status == QTD_PAYLOAD_ALLOC)) {
+			if (slots == priv->int_slots) {
+				if (state == PTD_STATE_QTD_RELOAD)
+					dev_err(hcd->self.controller,
+						"%s: PTD_STATE_QTD_RELOAD on "
+						"interrupt packet\n", __func__);
+				if (state != PTD_STATE_QTD_RELOAD)
+					create_ptd_int(qh, qtd, &ptd);
+			} else {
+				if (state != PTD_STATE_QTD_RELOAD)
+					create_ptd_atl(qh, qtd, &ptd);
+			}
 
-			if (qtd->urb->status == -EINPROGRESS)
-				qtd->urb->status = 0;
+			start_bus_transfer(hcd, ptd_offset, slot, slots, qtd,
+				qh, &ptd);
+		}
+	}
 
-			urb = qtd->urb;
-			qtd = clean_up_qtdlist(qtd, qh);
-			isp1760_urb_done(hcd, urb);
+	if (modified)
+		schedule_ptds(hcd);
 
-		} else {
-			/* next QTD of this URB */
+	/* ISP1760 Errata 2 explains that interrupts may be missed (or not
+	   happen?) if two USB devices are running simultaneously. Perhaps
+	   this happens when a PTD is finished during interrupt handling;
+	   enable SOF interrupts if PTDs are still scheduled when exiting this
+	   interrupt handler, just to be safe. */
 
-			qtd = clean_this_qtd(qtd, qh);
-			BUG_ON(!qtd);
-		}
+	if (priv->active_ptds != last_active_ptds) {
+		if (priv->active_ptds > 0)
+			reg_write32(hcd->regs, HC_INTERRUPT_ENABLE,
+						INTERRUPT_ENABLE_SOT_MASK);
+		else
+			reg_write32(hcd->regs, HC_INTERRUPT_ENABLE,
+						INTERRUPT_ENABLE_MASK);
+		last_active_ptds = priv->active_ptds;
+	}
 
-		if (qtd)
-			enqueue_an_INT_packet(hcd, qh, qtd);
+	irqret = IRQ_HANDLED;
+leave:
+	spin_unlock(&priv->lock);
 
-		skip_map = reg_read32(hcd->regs, HC_INT_PTD_SKIPMAP_REG);
-	}
+	return irqret;
 }
 
 static int qtd_fill(struct isp1760_qtd *qtd, void *databuffer, size_t len)
@@ -1380,197 +1426,136 @@ cleanup:
 	qtd_list_free(head);
 }
 
-static int enqueue_qtdlist(struct usb_hcd *hcd, struct urb *urb,
-		struct list_head *qtd_list, gfp_t mem_flags, packet_enqueue *p)
-{
-	struct isp1760_hcd *priv = hcd_to_priv(hcd);
-	struct isp1760_qtd *qtd;
-	struct isp1760_qh *qh = NULL;
-	unsigned long flags;
-	int qh_empty;
-	int rc;
-
-	spin_lock_irqsave(&priv->lock, flags);
-	if (!HCD_HW_ACCESSIBLE(hcd)) {
-		rc = -ESHUTDOWN;
-		goto done;
-	}
-	rc = usb_hcd_link_urb_to_ep(hcd, urb);
-	if (rc)
-		goto done;
-
-	qh = urb->ep->hcpriv;
-	if (!qh) {
-		qh = isp1760_qh_alloc(GFP_ATOMIC);
-		if (!qh) {
-			usb_hcd_unlink_urb_from_ep(hcd, urb);
-			rc = -ENOMEM;
-			goto done;
-		}
-		if (!usb_pipecontrol(urb->pipe))
-			usb_settoggle(urb->dev, usb_pipeendpoint(urb->pipe),
-						!usb_pipein(urb->pipe), 1);
-		urb->ep->hcpriv = qh;
-	}
-
-	qh_empty = list_empty(&qh->qtd_list);
-	list_splice_tail(qtd_list, &qh->qtd_list);
-	if (qh_empty) {
-		qtd = list_entry(qtd_list->next, struct isp1760_qtd, qtd_list);
-		p(hcd, qh, qtd);
-	}
-
-done:
-	spin_unlock_irqrestore(&priv->lock, flags);
-	if (!qh)
-		qtd_list_free(qtd_list);
-	return rc;
-}
-
 static int isp1760_urb_enqueue(struct usb_hcd *hcd, struct urb *urb,
 		gfp_t mem_flags)
 {
-	struct list_head qtd_list;
-	packet_enqueue *pe;
-
-	INIT_LIST_HEAD(&qtd_list);
+	struct isp1760_hcd *priv = hcd_to_priv(hcd);
+	struct list_head *ep_queue;
+	struct isp1760_qh *qh, *qhit;
+	unsigned long spinflags;
+	LIST_HEAD(new_qtds);
+	int retval;
+	int qh_in_queue;
 
 	switch (usb_pipetype(urb->pipe)) {
 	case PIPE_CONTROL:
+		ep_queue = &priv->controlqhs;
+		break;
 	case PIPE_BULK:
-		pe = enqueue_an_ATL_packet;
+		ep_queue = &priv->bulkqhs;
 		break;
-
 	case PIPE_INTERRUPT:
-		pe = enqueue_an_INT_packet;
+		if (urb->interval < 0)
+			return -EINVAL;
+		/* FIXME: Check bandwidth  */
+		ep_queue = &priv->interruptqhs;
 		break;
-
 	case PIPE_ISOCHRONOUS:
-		dev_err(hcd->self.controller, "PIPE_ISOCHRONOUS ain't supported\n");
+		dev_err(hcd->self.controller, "%s: isochronous USB packets "
+							"not yet supported\n",
+							__func__);
+		return -EPIPE;
 	default:
+		dev_err(hcd->self.controller, "%s: unknown pipe type\n",
+							__func__);
 		return -EPIPE;
 	}
 
-	packetize_urb(hcd, urb, &qtd_list, mem_flags);
-	if (list_empty(&qtd_list))
-		return -ENOMEM;
-
-	return enqueue_qtdlist(hcd, urb, &qtd_list, mem_flags, pe);
-}
-
-static int isp1760_urb_dequeue(struct usb_hcd *hcd, struct urb *urb, int status)
-{
-	struct isp1760_hcd *priv = hcd_to_priv(hcd);
-	struct inter_packet_info *ints;
-	u32 i;
-	u32 reg_base, skip_reg;
-	unsigned long flags;
-	struct ptd ptd;
-	packet_enqueue *pe;
+	if (usb_pipein(urb->pipe))
+		urb->actual_length = 0;
 
-	switch (usb_pipetype(urb->pipe)) {
-	case PIPE_ISOCHRONOUS:
-		return -EPIPE;
-		break;
+	packetize_urb(hcd, urb, &new_qtds, mem_flags);
+	if (list_empty(&new_qtds))
+		return -ENOMEM;
+	urb->hcpriv = NULL; /* Used to signal unlink to interrupt handler */
 
-	case PIPE_INTERRUPT:
-		ints = priv->int_ints;
-		reg_base = INT_PTD_OFFSET;
-		skip_reg = HC_INT_PTD_SKIPMAP_REG;
-		pe = enqueue_an_INT_packet;
-		break;
+	retval = 0;
+	spin_lock_irqsave(&priv->lock, spinflags);
 
-	default:
-		ints = priv->atl_ints;
-		reg_base = ATL_PTD_OFFSET;
-		skip_reg = HC_ATL_PTD_SKIPMAP_REG;
-		pe =  enqueue_an_ATL_packet;
-		break;
+	if (!test_bit(HCD_FLAG_HW_ACCESSIBLE, &hcd->flags)) {
+		retval = -ESHUTDOWN;
+		goto out;
 	}
+	retval = usb_hcd_link_urb_to_ep(hcd, urb);
+	if (retval)
+		goto out;
 
-	memset(&ptd, 0, sizeof(ptd));
-	spin_lock_irqsave(&priv->lock, flags);
-
-	for (i = 0; i < 32; i++) {
-		if (!ints[i].qh)
-			continue;
-		WARN_ON(!ints[i].qtd);
-
-		if (ints[i].qtd->urb == urb) {
-			u32 skip_map;
-			struct isp1760_qtd *qtd;
-			struct isp1760_qh *qh;
-
-			skip_map = reg_read32(hcd->regs, skip_reg);
-			skip_map |= 1 << i;
-			reg_write32(hcd->regs, skip_reg, skip_map);
-
-			ptd_write(hcd->regs, reg_base, i, &ptd);
-
-			qtd = ints[i].qtd;
-			qh = ints[i].qh;
-
-			free_mem(hcd, qtd);
-			qtd = clean_up_qtdlist(qtd, qh);
-
-			ints[i].qh = NULL;
-			ints[i].qtd = NULL;
-
-			urb->status = status;
-			isp1760_urb_done(hcd, urb);
-			if (qtd)
-				pe(hcd, qh, qtd);
-			break;
-
-		} else {
-			struct isp1760_qtd *qtd;
-
-			list_for_each_entry(qtd, &ints[i].qtd->qtd_list,
-								qtd_list) {
-				if (qtd->urb == urb) {
-					clean_up_qtdlist(qtd, ints[i].qh);
-					isp1760_urb_done(hcd, urb);
-					qtd = NULL;
-					break;
-				}
-			}
-
-			/* We found the urb before the last slot */
-			if (!qtd)
+	qh = urb->ep->hcpriv;
+	if (qh) {
+		qh_in_queue = 0;
+		list_for_each_entry(qhit, ep_queue, qh_list) {
+			if (qhit == qh) {
+				qh_in_queue = 1;
 				break;
+			}
+		}
+		if (!qh_in_queue)
+			list_add_tail(&qh->qh_list, ep_queue);
+	} else {
+		qh = qh_alloc(GFP_ATOMIC);
+		if (!qh) {
+			retval = -ENOMEM;
+			goto out;
 		}
+		list_add_tail(&qh->qh_list, ep_queue);
+		urb->ep->hcpriv = qh;
 	}
 
-	spin_unlock_irqrestore(&priv->lock, flags);
-	return 0;
+	list_splice_tail(&new_qtds, &qh->qtd_list);
+	schedule_ptds(hcd);
+
+out:
+	spin_unlock_irqrestore(&priv->lock, spinflags);
+	return retval;
 }
 
-static irqreturn_t isp1760_irq(struct usb_hcd *hcd)
+static int isp1760_urb_dequeue(struct usb_hcd *hcd, struct urb *urb,
+		int status)
 {
 	struct isp1760_hcd *priv = hcd_to_priv(hcd);
-	u32 imask;
-	irqreturn_t irqret = IRQ_NONE;
+	struct isp1760_qh *qh;
+	struct isp1760_qtd *qtd;
+	struct ptd ptd;
+	unsigned long spinflags;
+	int retval = 0;
 
-	spin_lock(&priv->lock);
+	spin_lock_irqsave(&priv->lock, spinflags);
 
-	if (!(hcd->state & HC_STATE_RUNNING))
-		goto leave;
+	qh = urb->ep->hcpriv;
+	if (!qh) {
+		retval = -EINVAL;
+		goto out;
+	}
 
-	imask = reg_read32(hcd->regs, HC_INTERRUPT_REG);
-	if (unlikely(!imask))
-		goto leave;
+	/* We need to forcefully reclaim the slot since some transfers never
+	   return, e.g. interrupt transfers and NAKed bulk transfers. */
+	if (qh->slot > -1) {
+		memset(&ptd, 0, sizeof(ptd));
+		if (usb_pipebulk(urb->pipe)) {
+			priv->atl_slots[qh->slot].qh = NULL;
+			priv->atl_slots[qh->slot].qtd = NULL;
+			ptd_write(hcd->regs, ATL_PTD_OFFSET, qh->slot, &ptd);
+		} else {
+			priv->int_slots[qh->slot].qh = NULL;
+			priv->int_slots[qh->slot].qtd = NULL;
+			ptd_write(hcd->regs, INT_PTD_OFFSET, qh->slot, &ptd);
+		}
+		priv->active_ptds--;
+		qh->slot = -1;
+	}
 
-	reg_write32(hcd->regs, HC_INTERRUPT_REG, imask);
-	if (imask & (HC_ATL_INT | HC_SOT_INT))
-		do_atl_int(hcd);
+	list_for_each_entry(qtd, &qh->qtd_list, qtd_list) {
+		if (qtd->urb == urb)
+			qtd->status = QTD_RETIRE;
+	}
 
-	if (imask & HC_INTL_INT)
-		do_intl_int(hcd);
+	urb->status = status;
+	schedule_ptds(hcd);
 
-	irqret = IRQ_HANDLED;
-leave:
-	spin_unlock(&priv->lock);
-	return irqret;
+out:
+	spin_unlock_irqrestore(&priv->lock, spinflags);
+
+	return retval;
 }
 
 static int isp1760_hub_status_data(struct usb_hcd *hcd, char *buf)
@@ -1661,7 +1646,7 @@ static int check_reset_complete(struct usb_hcd *hcd, int index,
 	/* if reset finished and it's still not enabled -- handoff */
 	if (!(port_status & PORT_PE)) {
 
-		dev_err(hcd->self.controller,
+		dev_info(hcd->self.controller,
 					"port %d full speed --> companion\n",
 					index + 1);
 
@@ -1670,7 +1655,7 @@ static int check_reset_complete(struct usb_hcd *hcd, int index,
 		reg_write32(hcd->regs, HC_PORTSC1, port_status);
 
 	} else
-		dev_err(hcd->self.controller, "port %d high speed\n",
+		dev_info(hcd->self.controller, "port %d high speed\n",
 								index + 1);
 
 	return port_status;
@@ -1948,43 +1933,32 @@ static void isp1760_endpoint_disable(struct usb_hcd *hcd,
 	struct isp1760_hcd *priv = hcd_to_priv(hcd);
 	struct isp1760_qh *qh;
 	struct isp1760_qtd *qtd;
-	unsigned long flags;
+	unsigned long spinflags;
+	int do_iter;
 
-	spin_lock_irqsave(&priv->lock, flags);
+	spin_lock_irqsave(&priv->lock, spinflags);
 	qh = ep->hcpriv;
 	if (!qh)
 		goto out;
 
-	ep->hcpriv = NULL;
-	do {
-		/* more than entry might get removed */
-		if (list_empty(&qh->qtd_list))
-			break;
-
-		qtd = list_first_entry(&qh->qtd_list, struct isp1760_qtd,
-				qtd_list);
-
-		if (qtd->status & URB_ENQUEUED) {
-			spin_unlock_irqrestore(&priv->lock, flags);
-			isp1760_urb_dequeue(hcd, qtd->urb, -ECONNRESET);
-			spin_lock_irqsave(&priv->lock, flags);
-		} else {
-			struct urb *urb;
-
-			urb = qtd->urb;
-			clean_up_qtdlist(qtd, qh);
-			urb->status = -ECONNRESET;
-			isp1760_urb_done(hcd, urb);
+	do_iter = !list_empty(&qh->qtd_list);
+	while (do_iter) {
+		do_iter = 0;
+		list_for_each_entry(qtd, &qh->qtd_list, qtd_list) {
+			if (qtd->urb->ep == ep) {
+				spin_unlock_irqrestore(&priv->lock, spinflags);
+				isp1760_urb_dequeue(hcd, qtd->urb, -ECONNRESET);
+				spin_lock_irqsave(&priv->lock, spinflags);
+				do_iter = 1;
+				break; /* Restart iteration */
+			}
 		}
-	} while (1);
+	}
+	ep->hcpriv = NULL;
+	/* Cannot free qh here since it will be parsed by schedule_ptds() */
 
-	qh_destroy(qh);
-	/* remove requests and leak them.
-	 * ATL are pretty fast done, INT could take a while...
-	 * The latter shoule be removed
-	 */
 out:
-	spin_unlock_irqrestore(&priv->lock, flags);
+	spin_unlock_irqrestore(&priv->lock, spinflags);
 }
 
 static int isp1760_get_frame(struct usb_hcd *hcd)
@@ -2048,6 +2022,13 @@ static const struct hc_driver isp1760_hc_driver = {
 
 int __init init_kmem_once(void)
 {
+	urb_listitem_cachep = kmem_cache_create("isp1760 urb_listitem",
+			sizeof(struct urb_listitem), 0, SLAB_TEMPORARY |
+			SLAB_MEM_SPREAD, NULL);
+
+	if (!urb_listitem_cachep)
+		return -ENOMEM;
+
 	qtd_cachep = kmem_cache_create("isp1760_qtd",
 			sizeof(struct isp1760_qtd), 0, SLAB_TEMPORARY |
 			SLAB_MEM_SPREAD, NULL);
@@ -2070,6 +2051,7 @@ void deinit_kmem_cache(void)
 {
 	kmem_cache_destroy(qtd_cachep);
 	kmem_cache_destroy(qh_cachep);
+	kmem_cache_destroy(urb_listitem_cachep);
 }
 
 struct usb_hcd *isp1760_register(phys_addr_t res_start, resource_size_t res_len,
diff --git a/drivers/usb/host/isp1760-hcd.h b/drivers/usb/host/isp1760-hcd.h
index 056e046b0d42..014a7dfadf91 100644
--- a/drivers/usb/host/isp1760-hcd.h
+++ b/drivers/usb/host/isp1760-hcd.h
@@ -104,7 +104,7 @@ struct ptd {
 #define ATL_PTD_OFFSET		0x0c00
 #define PAYLOAD_OFFSET		0x1000
 
-struct inter_packet_info {
+struct slotinfo {
 	struct isp1760_qh *qh;
 	struct isp1760_qtd *qtd;
 };
@@ -154,54 +154,52 @@ struct memory_chunk {
 
 /* ATL */
 /* DW0 */
-#define PTD_VALID			1
-#define PTD_LENGTH(x)			(((u32) x) << 3)
-#define PTD_MAXPACKET(x)		(((u32) x) << 18)
-#define PTD_MULTI(x)			(((u32) x) << 29)
-#define PTD_ENDPOINT(x)			(((u32)	x) << 31)
+#define DW0_VALID_BIT			1
+#define FROM_DW0_VALID(x)		((x) & 0x01)
+#define TO_DW0_LENGTH(x)		(((u32) x) << 3)
+#define TO_DW0_MAXPACKET(x)		(((u32) x) << 18)
+#define TO_DW0_MULTI(x)			(((u32) x) << 29)
+#define TO_DW0_ENDPOINT(x)		(((u32)	x) << 31)
 /* DW1 */
-#define PTD_DEVICE_ADDR(x)		(((u32) x) << 3)
-#define PTD_PID_TOKEN(x)		(((u32) x) << 10)
-#define PTD_TRANS_BULK			((u32) 2 << 12)
-#define PTD_TRANS_INT			((u32) 3 << 12)
-#define PTD_TRANS_SPLIT			((u32) 1 << 14)
-#define PTD_SE_USB_LOSPEED		((u32) 2 << 16)
-#define PTD_PORT_NUM(x)			(((u32) x) << 18)
-#define PTD_HUB_NUM(x)			(((u32) x) << 25)
-#define PTD_PING(x)			(((u32) x) << 26)
+#define TO_DW1_DEVICE_ADDR(x)		(((u32) x) << 3)
+#define TO_DW1_PID_TOKEN(x)		(((u32) x) << 10)
+#define DW1_TRANS_BULK			((u32) 2 << 12)
+#define DW1_TRANS_INT			((u32) 3 << 12)
+#define DW1_TRANS_SPLIT			((u32) 1 << 14)
+#define DW1_SE_USB_LOSPEED		((u32) 2 << 16)
+#define TO_DW1_PORT_NUM(x)		(((u32) x) << 18)
+#define TO_DW1_HUB_NUM(x)		(((u32) x) << 25)
 /* DW2 */
-#define PTD_RL_CNT(x)			(((u32) x) << 25)
-#define PTD_DATA_START_ADDR(x)		(((u32) x) << 8)
-#define BASE_ADDR			0x1000
+#define TO_DW2_DATA_START_ADDR(x)	(((u32) x) << 8)
+#define TO_DW2_RL(x)			((x) << 25)
+#define FROM_DW2_RL(x)			(((x) >> 25) & 0xf)
 /* DW3 */
-#define PTD_CERR(x)			(((u32) x) << 23)
-#define PTD_NAC_CNT(x)			(((u32) x) << 19)
-#define PTD_ACTIVE			((u32) 1 << 31)
-#define PTD_DATA_TOGGLE(x)		(((u32) x) << 25)
-
-#define DW3_HALT_BIT			(1 << 30)
+#define FROM_DW3_NRBYTESTRANSFERRED(x)		((x) & 0x7fff)
+#define FROM_DW3_SCS_NRBYTESTRANSFERRED(x)	((x) & 0x07ff)
+#define TO_DW3_NAKCOUNT(x)		((x) << 19)
+#define FROM_DW3_NAKCOUNT(x)		(((x) >> 19) & 0xf)
+#define TO_DW3_CERR(x)			((x) << 23)
+#define FROM_DW3_CERR(x)		(((x) >> 23) & 0x3)
+#define TO_DW3_DATA_TOGGLE(x)		((x) << 25)
+#define FROM_DW3_DATA_TOGGLE(x)		(((x) >> 25) & 0x1)
+#define TO_DW3_PING(x)			((x) << 26)
+#define FROM_DW3_PING(x)		(((x) >> 26) & 0x1)
 #define DW3_ERROR_BIT			(1 << 28)
-#define DW3_QTD_ACTIVE			(1 << 31)
+#define DW3_BABBLE_BIT			(1 << 29)
+#define DW3_HALT_BIT			(1 << 30)
+#define DW3_ACTIVE_BIT			(1 << 31)
 
 #define INT_UNDERRUN			(1 << 2)
 #define INT_BABBLE			(1 << 1)
 #define INT_EXACT			(1 << 0)
 
-#define DW1_GET_PID(x)			(((x) >> 10) & 0x3)
-#define PTD_XFERRED_LENGTH(x)		((x) & 0x7fff)
-#define PTD_XFERRED_LENGTH_LO(x)	((x) & 0x7ff)
-
 #define SETUP_PID	(2)
 #define IN_PID		(1)
 #define OUT_PID		(0)
-#define GET_QTD_TOKEN_TYPE(x)	((x) & 0x3)
-
-#define DATA_TOGGLE		(1 << 31)
-#define GET_DATA_TOGGLE(x)	((x) >> 31)
 
 /* Errata 1 */
 #define RL_COUNTER	(0)
 #define NAK_COUNTER	(0)
 #define ERR_COUNTER	(2)
 
-#endif
+#endif /* _ISP1760_HCD_H_ */