Subject: usb: fix uss720 schedule with interrupts off

From: Thomas Sailer <[email-masked]>
Date: Fri, 09 Sep 2005 10:43:50 +0200

This patch fixes the long standing schedule with interrupts off problem
of the uss720 driver. The problem is caused by the parport layer calling
the save and restore methods within a write_lock_irqsave guarded region.
The fix is to issue the control transaction requests required by save
and restore asynchronously.

Signed-off-by: Thomas Sailer, <[email-masked]>
Signed-off-by: Greg Kroah-Hartman <[email-masked]>

---
 drivers/usb/misc/uss720.c |  393 +++++++++++++++++++++++++++++++---------------
 1 file changed, 270 insertions(+), 123 deletions(-)

--- gregkh-2.6.orig/drivers/usb/misc/uss720.c	2005-09-12 11:10:10.000000000 -0700
+++ gregkh-2.6/drivers/usb/misc/uss720.c	2005-09-12 11:11:43.000000000 -0700
@@ -3,8 +3,8 @@
 /*
  *	uss720.c  --  USS720 USB Parport Cable.
  *
- *	Copyright (C) 1999
- *	    Thomas Sailer ([email-masked])
+ *	Copyright (C) 1999, 2005
+ *	    Thomas Sailer ([email-masked])
  *
  *	This program is free software; you can redistribute it and/or modify
  *	it under the terms of the GNU General Public License as published by
@@ -23,103 +23,240 @@
  *  Based on parport_pc.c
  *
  *  History:
- *   0.1  04.08.99  Created
- *   0.2  07.08.99  Some fixes mainly suggested by Tim Waugh
- *		    Interrupt handling currently disabled because
- *		    usb_request_irq crashes somewhere within ohci.c
- *		    for no apparent reason (that is for me, anyway)
- *		    ECP currently untested
- *   0.3  10.08.99  fixing merge errors
- *   0.4  13.08.99  Added Vendor/Product ID of Brad Hard's cable
- *   0.5  20.09.99  usb_control_msg wrapper used
- *        Nov01.00  usb_device_table support by Adam J. Richter
- *        08.04.01  Identify version on module load.  gb
+ *   0.1  04.08.1999  Created
+ *   0.2  07.08.1999  Some fixes mainly suggested by Tim Waugh
+ *		      Interrupt handling currently disabled because
+ *		      usb_request_irq crashes somewhere within ohci.c
+ *		      for no apparent reason (that is for me, anyway)
+ *		      ECP currently untested
+ *   0.3  10.08.1999  fixing merge errors
+ *   0.4  13.08.1999  Added Vendor/Product ID of Brad Hard's cable
+ *   0.5  20.09.1999  usb_control_msg wrapper used
+ *        Nov01.2000  usb_device_table support by Adam J. Richter
+ *        08.04.2001  Identify version on module load.  gb
+ *   0.6  02.09.2005  Fix "scheduling in interrupt" problem by making save/restore
+ *                    context asynchronous
  *
  */
 
 /*****************************************************************************/
 
+#define DEBUG
+
 #include <linux/module.h>
 #include <linux/socket.h>
 #include <linux/parport.h>
 #include <linux/init.h>
 #include <linux/usb.h>
 #include <linux/delay.h>
+#include <linux/completion.h>
+#include <linux/kref.h>
 
 /*
  * Version Information
  */
-#define DRIVER_VERSION "v0.5"
-#define DRIVER_AUTHOR "Thomas M. Sailer, [email-masked]"
+#define DRIVER_VERSION "v0.6"
+#define DRIVER_AUTHOR "Thomas M. Sailer, [email-masked]"
 #define DRIVER_DESC "USB Parport Cable driver for Cables using the Lucent Technologies USS720 Chip"
 
 /* --------------------------------------------------------------------- */
 
 struct parport_uss720_private {
 	struct usb_device *usbdev;
-	void *irqhandle;
-	unsigned int irqpipe;
-	unsigned char reg[7];  /* USB registers */
+	struct parport *pp;
+	struct kref ref_count;
+	__u8 reg[7];  /* USB registers */
+	struct list_head asynclist;
+	spinlock_t asynclock;
+};
+
+struct uss720_async_request {
+	struct parport_uss720_private *priv;
+	struct kref ref_count;
+	struct list_head asynclist;
+	struct completion compl;
+	struct urb *urb;
+	struct usb_ctrlrequest dr;
+	__u8 reg[7];
 };
 
 /* --------------------------------------------------------------------- */
 
-static int get_1284_register(struct parport *pp, unsigned char reg, unsigned char *val)
+static void destroy_priv(struct kref *kref)
 {
-	struct parport_uss720_private *priv = pp->private_data;
-	struct usb_device *usbdev = priv->usbdev;
-	static const unsigned char regindex[9] = {
-		4, 0, 1, 5, 5, 0, 2, 3, 6
-	};
-	int ret;
+	struct parport_uss720_private *priv = container_of(kref, struct parport_uss720_private, ref_count);
 
-	if (!usbdev)
-		return -1;
-	ret = usb_control_msg(usbdev, usb_rcvctrlpipe(usbdev,0), 3, 0xc0, ((unsigned int)reg) << 8, 0, priv->reg, 7, 1000);
-	if (ret != 7) {
-		printk(KERN_DEBUG "uss720: get_1284_register(%d) failed, status 0x%x expected 7\n",
-		       (unsigned int)reg, ret);
-		ret = -1;
-	} else {
+	usb_put_dev(priv->usbdev);
+	kfree(priv);
+	dbg("destroying priv datastructure");
+}
+
+static void destroy_async(struct kref *kref)
+{
+	struct uss720_async_request *rq = container_of(kref, struct uss720_async_request, ref_count);
+	struct parport_uss720_private *priv = rq->priv;
+	unsigned long flags;
+
+	if (likely(rq->urb))
+		usb_free_urb(rq->urb);
+	spin_lock_irqsave(&priv->asynclock, flags);
+	list_del_init(&rq->asynclist);
+	spin_unlock_irqrestore(&priv->asynclock, flags);
+	kfree(rq);
+	kref_put(&priv->ref_count, destroy_priv);
+}
+
+/* --------------------------------------------------------------------- */
+
+static void async_complete(struct urb *urb, struct pt_regs *ptregs)
+{
+	struct uss720_async_request *rq;
+	struct parport *pp;
+	struct parport_uss720_private *priv;
+
+	rq = urb->context;
+	priv = rq->priv;
+	pp = priv->pp;
+	if (urb->status) {
+		err("async_complete: urb error %d", urb->status);
+	} else if (rq->dr.bRequest == 3) {
+		memcpy(priv->reg, rq->reg, sizeof(priv->reg));
 #if 0
-		printk(KERN_DEBUG "uss720: get_1284_register(%d) return %02x %02x %02x %02x %02x %02x %02x\n",
-		       (unsigned int)reg, (unsigned int)priv->reg[0], (unsigned int)priv->reg[1],
-		       (unsigned int)priv->reg[2], (unsigned int)priv->reg[3], (unsigned int)priv->reg[4],
-		       (unsigned int)priv->reg[5], (unsigned int)priv->reg[6]);
+		dbg("async_complete regs %02x %02x %02x %02x %02x %02x %02x",
+		    (unsigned int)priv->reg[0], (unsigned int)priv->reg[1], (unsigned int)priv->reg[2],
+		    (unsigned int)priv->reg[3], (unsigned int)priv->reg[4], (unsigned int)priv->reg[5],
+		    (unsigned int)priv->reg[6]);
 #endif
 		/* if nAck interrupts are enabled and we have an interrupt, call the interrupt procedure */
-		if (priv->reg[2] & priv->reg[1] & 0x10)
+		if (rq->reg[2] & rq->reg[1] & 0x10 && pp)
 			parport_generic_irq(0, pp, NULL);
-		ret = 0;
 	}
-	if (val)
-		*val = priv->reg[(reg >= 9) ? 0 : regindex[reg]];
-	return ret;
+	complete(&rq->compl);
+	kref_put(&rq->ref_count, destroy_async);
 }
 
-static int set_1284_register(struct parport *pp, unsigned char reg, unsigned char val)
+static struct uss720_async_request *submit_async_request(struct parport_uss720_private *priv,
+							 __u8 request, __u8 requesttype, __u16 value, __u16 index,
+							 unsigned int mem_flags)
 {
-	struct parport_uss720_private *priv = pp->private_data;
-	struct usb_device *usbdev = priv->usbdev;
+	struct usb_device *usbdev;
+	struct uss720_async_request *rq;
+	unsigned long flags;
 	int ret;
 
+	if (!priv)
+		return NULL;
+	usbdev = priv->usbdev;
 	if (!usbdev)
-		return -1;
-	ret = usb_control_msg(usbdev, usb_sndctrlpipe(usbdev,0), 4, 0x40, (((unsigned int)reg) << 8) | val, 0, NULL, 0, 1000);
-	if (ret) {
-		printk(KERN_DEBUG "uss720: set_1284_register(%u,0x%02x) failed, status 0x%x\n", 
-		       (unsigned int)reg, (unsigned int)val, ret);
-	} else {
-#if 0
-		printk(KERN_DEBUG "uss720: set_1284_register(%u,0x%02x)\n", 
-		       (unsigned int)reg, (unsigned int)val);
-#endif
+		return NULL;
+	rq = kmalloc(sizeof(struct uss720_async_request), mem_flags);
+	if (!rq) {
+		err("submit_async_request out of memory");
+		return NULL;
+	}
+	kref_init(&rq->ref_count);
+	INIT_LIST_HEAD(&rq->asynclist);
+	init_completion(&rq->compl);
+	kref_get(&priv->ref_count);
+	rq->priv = priv;
+	rq->urb = usb_alloc_urb(0, mem_flags);
+	if (!rq->urb) {
+		kref_put(&rq->ref_count, destroy_async);
+		err("submit_async_request out of memory");
+		return NULL;
+	}
+	rq->dr.bRequestType = requesttype;
+	rq->dr.bRequest = request;
+	rq->dr.wValue = cpu_to_le16(value);
+	rq->dr.wIndex = cpu_to_le16(index);
+	rq->dr.wLength = cpu_to_le16((request == 3) ? sizeof(rq->reg) : 0);
+	usb_fill_control_urb(rq->urb, usbdev, (requesttype & 0x80) ? usb_rcvctrlpipe(usbdev, 0) : usb_sndctrlpipe(usbdev, 0),
+			     (unsigned char *)&rq->dr,
+			     (request == 3) ? rq->reg : NULL, (request == 3) ? sizeof(rq->reg) : 0, async_complete, rq);
+	/* rq->urb->transfer_flags |= URB_ASYNC_UNLINK; */
+	spin_lock_irqsave(&priv->asynclock, flags);
+	list_add_tail(&rq->asynclist, &priv->asynclist);
+	spin_unlock_irqrestore(&priv->asynclock, flags);
+	ret = usb_submit_urb(rq->urb, mem_flags);
+	if (!ret) {
+		kref_get(&rq->ref_count);
+		return rq;
+	}
+	kref_put(&rq->ref_count, destroy_async);
+	err("submit_async_request submit_urb failed with %d", ret);
+	return NULL;
+}
+
+static unsigned int kill_all_async_requests_priv(struct parport_uss720_private *priv)
+{
+	struct uss720_async_request *rq;
+	unsigned long flags;
+	unsigned int ret = 0;
+
+	spin_lock_irqsave(&priv->asynclock, flags);
+	list_for_each_entry(rq, &priv->asynclist, asynclist) {
+		usb_unlink_urb(rq->urb);
+		ret++;
 	}
+	spin_unlock_irqrestore(&priv->asynclock, flags);
 	return ret;
 }
 
 /* --------------------------------------------------------------------- */
 
+static int get_1284_register(struct parport *pp, unsigned char reg, unsigned char *val, unsigned int mem_flags)
+{
+	struct parport_uss720_private *priv;
+	struct uss720_async_request *rq;
+	static const unsigned char regindex[9] = {
+		4, 0, 1, 5, 5, 0, 2, 3, 6
+	};
+	int ret;
+
+	if (!pp)
+		return -EIO;
+	priv = pp->private_data;
+	rq = submit_async_request(priv, 3, 0xc0, ((unsigned int)reg) << 8, 0, mem_flags);
+	if (!rq) {
+		err("get_1284_register(%u) failed", (unsigned int)reg);
+		return -EIO;
+	}
+	if (!val) {
+		kref_put(&rq->ref_count, destroy_async);
+		return 0;
+	}
+	if (wait_for_completion_timeout(&rq->compl, HZ)) {
+		ret = rq->urb->status;
+		*val = priv->reg[(reg >= 9) ? 0 : regindex[reg]];
+		if (ret)
+			warn("get_1284_register: usb error %d", ret);
+		kref_put(&rq->ref_count, destroy_async);
+		return ret;
+	}
+	warn("get_1284_register timeout");
+	kill_all_async_requests_priv(priv);
+	return -EIO;
+}
+
+static int set_1284_register(struct parport *pp, unsigned char reg, unsigned char val, unsigned int mem_flags)
+{
+	struct parport_uss720_private *priv;
+	struct uss720_async_request *rq;
+
+	if (!pp)
+		return -EIO;
+	priv = pp->private_data;
+	rq = submit_async_request(priv, 4, 0x40, (((unsigned int)reg) << 8) | val, 0, mem_flags);
+	if (!rq) {
+		err("set_1284_register(%u,%u) failed", (unsigned int)reg, (unsigned int)val);
+		return -EIO;
+	}
+	kref_put(&rq->ref_count, destroy_async);
+	return 0;
+}
+
+/* --------------------------------------------------------------------- */
+
 /* ECR modes */
 #define ECR_SPP 00
 #define ECR_PS2 01
@@ -132,8 +269,9 @@ static int change_mode(struct parport *p
 {
 	struct parport_uss720_private *priv = pp->private_data;
 	int mode;
+	__u8 reg;
 
-	if (get_1284_register(pp, 6, NULL))
+	if (get_1284_register(pp, 6, &reg, GFP_KERNEL))
 		return -EIO;
 	/* Bits <7:5> contain the mode. */
 	mode = (priv->reg[2] >> 5) & 0x7;
@@ -153,7 +291,7 @@ static int change_mode(struct parport *p
 		case ECR_ECP: /* ECP Parallel Port mode */
 			/* Poll slowly. */
 			for (;;) {
-				if (get_1284_register(pp, 6, NULL))
+				if (get_1284_register(pp, 6, &reg, GFP_KERNEL))
 					return -EIO;
 				if (priv->reg[2] & 0x01)
 					break;
@@ -167,7 +305,9 @@ static int change_mode(struct parport *p
 		}
 	}
 	/* Set the mode. */
-	if (set_1284_register(pp, 6, m << 5))
+	if (set_1284_register(pp, 6, m << 5, GFP_KERNEL))
+		return -EIO;
+	if (get_1284_register(pp, 6, &reg, GFP_KERNEL))
 		return -EIO;
 	return 0;
 }
@@ -179,7 +319,7 @@ static int clear_epp_timeout(struct parp
 {
 	unsigned char stat;
 
-	if (get_1284_register(pp, 1, &stat))
+	if (get_1284_register(pp, 1, &stat, GFP_KERNEL))
 		return 1;
 	return stat & 1;
 }
@@ -205,14 +345,14 @@ static int uss720_irq(int usbstatus, voi
 
 static void parport_uss720_write_data(struct parport *pp, unsigned char d)
 {
-	set_1284_register(pp, 0, d);
+	set_1284_register(pp, 0, d, GFP_KERNEL);
 }
 
 static unsigned char parport_uss720_read_data(struct parport *pp)
 {
 	unsigned char ret;
 
-	if (get_1284_register(pp, 0, &ret))
+	if (get_1284_register(pp, 0, &ret, GFP_KERNEL))
 		return 0;
 	return ret;
 }
@@ -222,7 +362,7 @@ static void parport_uss720_write_control
 	struct parport_uss720_private *priv = pp->private_data;	
 
 	d = (d & 0xf) | (priv->reg[1] & 0xf0);
-	if (set_1284_register(pp, 2, d))
+	if (set_1284_register(pp, 2, d, GFP_KERNEL))
 		return;
 	priv->reg[1] = d;
 }
@@ -241,7 +381,7 @@ static unsigned char parport_uss720_frob
 	mask &= 0x0f;
 	val &= 0x0f;
 	d = (priv->reg[1] & (~mask)) ^ val;
-	if (set_1284_register(pp, 2, d))
+	if (set_1284_register(pp, 2, d, GFP_KERNEL))
 		return 0;
 	priv->reg[1] = d;
 	return d & 0xf;
@@ -251,7 +391,7 @@ static unsigned char parport_uss720_read
 {
 	unsigned char ret;
 
-	if (get_1284_register(pp, 1, &ret))
+	if (get_1284_register(pp, 1, &ret, GFP_KERNEL))
 		return 0;
 	return ret & 0xf8;
 }
@@ -262,7 +402,7 @@ static void parport_uss720_disable_irq(s
 	unsigned char d;
 
 	d = priv->reg[1] & ~0x10;
-	if (set_1284_register(pp, 2, d))
+	if (set_1284_register(pp, 2, d, GFP_KERNEL))
 		return;
 	priv->reg[1] = d;
 }
@@ -273,7 +413,7 @@ static void parport_uss720_enable_irq(st
 	unsigned char d;
 
 	d = priv->reg[1] | 0x10;
-	if (set_1284_register(pp, 2, d))
+	if (set_1284_register(pp, 2, d, GFP_KERNEL))
 		return;
 	priv->reg[1] = d;
 }
@@ -284,7 +424,7 @@ static void parport_uss720_data_forward 
 	unsigned char d;
 
 	d = priv->reg[1] & ~0x20;
-	if (set_1284_register(pp, 2, d))
+	if (set_1284_register(pp, 2, d, GFP_KERNEL))
 		return;
 	priv->reg[1] = d;
 }
@@ -295,7 +435,7 @@ static void parport_uss720_data_reverse 
 	unsigned char d;
 
 	d = priv->reg[1] | 0x20;
-	if (set_1284_register(pp, 2, d))
+	if (set_1284_register(pp, 2, d, GFP_KERNEL))
 		return;
 	priv->reg[1] = d;
 }
@@ -310,17 +450,23 @@ static void parport_uss720_save_state(st
 {
 	struct parport_uss720_private *priv = pp->private_data;	
 
-	if (get_1284_register(pp, 2, NULL))
+#if 0
+	if (get_1284_register(pp, 2, NULL, GFP_ATOMIC))
 		return;
+#endif
 	s->u.pc.ctr = priv->reg[1];
 	s->u.pc.ecr = priv->reg[2];
 }
 
 static void parport_uss720_restore_state(struct parport *pp, struct parport_state *s)
 {
-	set_1284_register(pp, 2, s->u.pc.ctr);
-	set_1284_register(pp, 6, s->u.pc.ecr);
-	get_1284_register(pp, 2, NULL);
+	struct parport_uss720_private *priv = pp->private_data;
+
+	set_1284_register(pp, 2, s->u.pc.ctr, GFP_ATOMIC);
+	set_1284_register(pp, 6, s->u.pc.ecr, GFP_ATOMIC);
+	get_1284_register(pp, 2, NULL, GFP_ATOMIC);
+	priv->reg[1] = s->u.pc.ctr;
+	priv->reg[2] = s->u.pc.ecr;
 }
 
 static size_t parport_uss720_epp_read_data(struct parport *pp, void *buf, size_t length, int flags)
@@ -331,7 +477,7 @@ static size_t parport_uss720_epp_read_da
 	if (change_mode(pp, ECR_EPP))
 		return 0;
 	for (; got < length; got++) {
-		if (get_1284_register(pp, 4, (char *)buf))
+		if (get_1284_register(pp, 4, (char *)buf, GFP_KERNEL))
 			break;
 		buf++;
 		if (priv->reg[0] & 0x01) {
@@ -352,10 +498,10 @@ static size_t parport_uss720_epp_write_d
 	if (change_mode(pp, ECR_EPP))
 		return 0;
 	for (; written < length; written++) {
-		if (set_1284_register(pp, 4, (char *)buf))
+		if (set_1284_register(pp, 4, (char *)buf, GFP_KERNEL))
 			break;
 		((char*)buf)++;
-		if (get_1284_register(pp, 1, NULL))
+		if (get_1284_register(pp, 1, NULL, GFP_KERNEL))
 			break;
 		if (priv->reg[0] & 0x01) {
 			clear_epp_timeout(pp);
@@ -390,7 +536,7 @@ static size_t parport_uss720_epp_read_ad
 	if (change_mode(pp, ECR_EPP))
 		return 0;
 	for (; got < length; got++) {
-		if (get_1284_register(pp, 3, (char *)buf))
+		if (get_1284_register(pp, 3, (char *)buf, GFP_KERNEL))
 			break;
 		buf++;
 		if (priv->reg[0] & 0x01) {
@@ -410,10 +556,10 @@ static size_t parport_uss720_epp_write_a
 	if (change_mode(pp, ECR_EPP))
 		return 0;
 	for (; written < length; written++) {
-		if (set_1284_register(pp, 3, *(char *)buf))
+		if (set_1284_register(pp, 3, *(char *)buf, GFP_KERNEL))
 			break;
 		buf++;
-		if (get_1284_register(pp, 1, NULL))
+		if (get_1284_register(pp, 1, NULL, GFP_KERNEL))
 			break;
 		if (priv->reg[0] & 0x01) {
 			clear_epp_timeout(pp);
@@ -467,7 +613,7 @@ static size_t parport_uss720_ecp_write_a
 	if (change_mode(pp, ECR_ECP))
 		return 0;
 	for (; written < len; written++) {
-		if (set_1284_register(pp, 5, *(char *)buffer))
+		if (set_1284_register(pp, 5, *(char *)buffer, GFP_KERNEL))
 			break;
 		buffer++;
 	}
@@ -536,93 +682,91 @@ static struct parport_operations parport
 static int uss720_probe(struct usb_interface *intf,
 			const struct usb_device_id *id)
 {
-	struct usb_device *usbdev = interface_to_usbdev(intf);
+	struct usb_device *usbdev = usb_get_dev(interface_to_usbdev(intf));
 	struct usb_host_interface *interface;
 	struct usb_host_endpoint *endpoint;
 	struct parport_uss720_private *priv;
 	struct parport *pp;
+	unsigned char reg;
 	int i;
 
-	printk(KERN_DEBUG "uss720: probe: vendor id 0x%x, device id 0x%x\n",
-	       le16_to_cpu(usbdev->descriptor.idVendor),
-	       le16_to_cpu(usbdev->descriptor.idProduct));
+	dbg("probe: vendor id 0x%x, device id 0x%x\n",
+	    le16_to_cpu(usbdev->descriptor.idVendor),
+	    le16_to_cpu(usbdev->descriptor.idProduct));
 
 	/* our known interfaces have 3 alternate settings */
-	if (intf->num_altsetting != 3)
+	if (intf->num_altsetting != 3) {
+		usb_put_dev(usbdev);
 		return -ENODEV;
-
+	}
 	i = usb_set_interface(usbdev, intf->altsetting->desc.bInterfaceNumber, 2);
-	printk(KERN_DEBUG "uss720: set inteface result %d\n", i);
+	dbg("set inteface result %d", i);
 
 	interface = intf->cur_altsetting;
 
 	/*
 	 * Allocate parport interface 
 	 */
-	printk(KERN_INFO "uss720: (C) 1999 by Thomas Sailer, <[email-masked]>\n");
-
-	if (!(priv = kmalloc(sizeof(struct parport_uss720_private), GFP_KERNEL)))
+	if (!(priv = kcalloc(sizeof(struct parport_uss720_private), 1, GFP_KERNEL))) {
+		usb_put_dev(usbdev);
 		return -ENOMEM;
+	}
+	priv->pp = NULL;
+	priv->usbdev = usbdev;
+	kref_init(&priv->ref_count);
+	spin_lock_init(&priv->asynclock);
+	INIT_LIST_HEAD(&priv->asynclist);
 	if (!(pp = parport_register_port(0, PARPORT_IRQ_NONE, PARPORT_DMA_NONE, &parport_uss720_ops))) {
-		printk(KERN_WARNING "usb-uss720: could not register parport\n");
+		warn("could not register parport");
 		goto probe_abort;
 	}
 
+	priv->pp = pp;
 	pp->private_data = priv;
-	priv->usbdev = usbdev;
 	pp->modes = PARPORT_MODE_PCSPP | PARPORT_MODE_TRISTATE | PARPORT_MODE_EPP | PARPORT_MODE_ECP | PARPORT_MODE_COMPAT;
 
 	/* set the USS720 control register to manual mode, no ECP compression, enable all ints */
-	set_1284_register(pp, 7, 0x00);
-	set_1284_register(pp, 6, 0x30);  /* PS/2 mode */
-	set_1284_register(pp, 2, 0x0c);
+	set_1284_register(pp, 7, 0x00, GFP_KERNEL);
+	set_1284_register(pp, 6, 0x30, GFP_KERNEL);  /* PS/2 mode */
+	set_1284_register(pp, 2, 0x0c, GFP_KERNEL);
 	/* debugging */
-	get_1284_register(pp, 0, NULL);
-	printk("uss720: reg: %02x %02x %02x %02x %02x %02x %02x\n",
-	       priv->reg[0], priv->reg[1], priv->reg[2], priv->reg[3], priv->reg[4], priv->reg[5], priv->reg[6]);
+	get_1284_register(pp, 0, &reg, GFP_KERNEL);
+	dbg("reg: %02x %02x %02x %02x %02x %02x %02x",
+	    priv->reg[0], priv->reg[1], priv->reg[2], priv->reg[3], priv->reg[4], priv->reg[5], priv->reg[6]);
 
 	endpoint = &interface->endpoint[2];
-	printk(KERN_DEBUG "uss720: epaddr %d interval %d\n", endpoint->desc.bEndpointAddress, endpoint->desc.bInterval);
-#if 0
-	priv->irqpipe = usb_rcvctrlpipe(usbdev, endpoint->bEndpointAddress);
-	i = usb_request_irq(usbdev, priv->irqpipe,
-				  uss720_irq, endpoint->bInterval,
-				  pp, &priv->irqhandle);
-	if (i) {
-		printk (KERN_WARNING "usb-uss720: usb_request_irq failed (0x%x)\n", i);
-		goto probe_abort_port;
-	}
-#endif
+	dbg("epaddr %d interval %d", endpoint->desc.bEndpointAddress, endpoint->desc.bInterval);
 	parport_announce_port(pp);
 
-	usb_set_intfdata (intf, pp);
+	usb_set_intfdata(intf, pp);
 	return 0;
 
-#if 0
-probe_abort_port:
-	parport_put_port(pp);
-#endif
 probe_abort:
-	kfree(priv);
+	kill_all_async_requests_priv(priv);
+	kref_put(&priv->ref_count, destroy_priv);
 	return -ENODEV;
 }
 
 static void uss720_disconnect(struct usb_interface *intf)
 {
-	struct parport *pp = usb_get_intfdata (intf);
+	struct parport *pp = usb_get_intfdata(intf);
 	struct parport_uss720_private *priv;
+	struct usb_device *usbdev;
 
-	usb_set_intfdata (intf, NULL);
+	dbg("disconnect");
+	usb_set_intfdata(intf, NULL);
 	if (pp) {
 		priv = pp->private_data;
-		parport_remove_port(pp);
-#if 0
-		usb_release_irq(usbdev, priv->irqhandle, priv->irqpipe);
-#endif
+		usbdev = priv->usbdev;
 		priv->usbdev = NULL;
+		priv->pp = NULL;
+		dbg("parport_remove_port");
+		parport_remove_port(pp);
 		parport_put_port(pp);
-		kfree(priv);
+		kill_all_async_requests_priv(priv);
+		kref_put(&priv->ref_count, destroy_priv);
 	}
+	dbg("disconnect done");
 }
 
 /* table of cables that work through this driver */
@@ -647,8 +791,8 @@ static struct usb_driver uss720_driver =
 
 /* --------------------------------------------------------------------- */
 
-MODULE_AUTHOR( DRIVER_AUTHOR );
-MODULE_DESCRIPTION( DRIVER_DESC );
+MODULE_AUTHOR(DRIVER_AUTHOR);
+MODULE_DESCRIPTION(DRIVER_DESC);
 MODULE_LICENSE("GPL");
 
 static int __init uss720_init(void)
@@ -659,6 +803,9 @@ static int __init uss720_init(void)
 		goto out;
 
 	info(DRIVER_VERSION ":" DRIVER_DESC);
+	info("NOTE: this is a special purpose driver to allow nonstandard");
+	info("protocols (eg. bitbang) over USS720 usb to parallel cables");
+	info("If you just want to connect to a printer, use usblp instead");
 out:
 	return retval;
 }