Index: usb-devel/drivers/media/usb/usbvision/usbvision-video.c
===================================================================
--- usb-devel.orig/drivers/media/usb/usbvision/usbvision-video.c
+++ usb-devel/drivers/media/usb/usbvision/usbvision-video.c
@@ -131,6 +131,25 @@ MODULE_LICENSE("GPL");
 MODULE_VERSION(USBVISION_VERSION_STRING);
 MODULE_ALIAS(DRIVER_ALIAS);
 
+#include <linux/kernfs.h>
+#include <linux/kobject.h>
+
+static void usbvision_check(struct usb_usbvision *usbvision, char *msg)
+{
+	struct kernfs_node *kn;
+
+	if (!video_is_registered(&usbvision->rdev)) {
+		dev_info(&usbvision->rdev.dev, "Not registered: %s\n", msg);
+	} else {
+		kn = kernfs_find_and_get(usbvision->rdev.dev.kobj.sd, "power");
+		if (kn) {
+			kernfs_put(kn);
+			dev_info(&usbvision->rdev.dev, "Power ok: %s\n", msg);
+		} else {
+			dev_err(&usbvision->rdev.dev, "Power gone: %s\n", msg);
+		}
+	}
+}
 
 /*****************************************************************************/
 /* SYSFS Code - Copied from the stv680.c usb module.			     */
@@ -314,6 +333,11 @@ static int usbvision_v4l2_open(struct fi
 	if (mutex_lock_interruptible(&usbvision->v4l2_lock))
 		return -ERESTARTSYS;
 
+	usbvision_check(usbvision, "v4l2 open");
+	if (usbvision->remove_pending) {
+		err_code = -ENODEV;
+		goto unlock;
+	}
 	if (usbvision->user) {
 		err_code = -EBUSY;
 	} else {
@@ -363,6 +387,7 @@ unlock:
 	mutex_unlock(&usbvision->v4l2_lock);
 
 	PDEBUG(DBG_IO, "success");
+	pr_info("v4l2 open -> %d\n", err_code);
 	return err_code;
 }
 
@@ -377,10 +402,13 @@ unlock:
 static int usbvision_v4l2_close(struct file *file)
 {
 	struct usb_usbvision *usbvision = video_drvdata(file);
+	int r;
 
 	PDEBUG(DBG_IO, "close");
 
+	usbvision_check(usbvision, "v4l2 close 1");
 	mutex_lock(&usbvision->v4l2_lock);
+	usbvision_check(usbvision, "v4l2 close 2");
 	usbvision_audio_off(usbvision);
 	usbvision_restart_isoc(usbvision);
 	usbvision_stop_isoc(usbvision);
@@ -389,11 +417,13 @@ static int usbvision_v4l2_close(struct f
 	usbvision_frames_free(usbvision);
 	usbvision_empty_framequeues(usbvision);
 	usbvision_scratch_free(usbvision);
+	usbvision_check(usbvision, "v4l2 close 3");
 
 	usbvision->user--;
+	r = usbvision->remove_pending;
 	mutex_unlock(&usbvision->v4l2_lock);
 
-	if (usbvision->remove_pending) {
+	if (r) {
 		printk(KERN_INFO "%s: Final disconnect\n", __func__);
 		usbvision_release(usbvision);
 		return 0;
@@ -453,6 +483,9 @@ static int vidioc_querycap(struct file *
 {
 	struct usb_usbvision *usbvision = video_drvdata(file);
 
+	if (!usbvision->dev)
+		return -ENODEV;
+
 	strscpy(vc->driver, "USBVision", sizeof(vc->driver));
 	strscpy(vc->card,
 		usbvision_device_data[usbvision->dev_model].model_string,
@@ -1073,6 +1106,12 @@ static int usbvision_radio_open(struct f
 
 	if (mutex_lock_interruptible(&usbvision->v4l2_lock))
 		return -ERESTARTSYS;
+
+	usbvision_check(usbvision, "radio open");
+	if (usbvision->remove_pending) {
+		err_code = -ENODEV;
+		goto out;
+	}
 	err_code = v4l2_fh_open(file);
 	if (err_code)
 		goto out;
@@ -1098,6 +1137,7 @@ static int usbvision_radio_open(struct f
 	}
 out:
 	mutex_unlock(&usbvision->v4l2_lock);
+	pr_info("radio open -> %d\n", err_code);
 	return err_code;
 }
 
@@ -1105,21 +1145,27 @@ out:
 static int usbvision_radio_close(struct file *file)
 {
 	struct usb_usbvision *usbvision = video_drvdata(file);
+	int r;
 
 	PDEBUG(DBG_IO, "");
 
+	usbvision_check(usbvision, "radio close 1");
 	mutex_lock(&usbvision->v4l2_lock);
+	usbvision_check(usbvision, "radio close 2");
 	/* Set packet size to 0 */
 	usbvision->iface_alt = 0;
-	usb_set_interface(usbvision->dev, usbvision->iface,
+	if (usbvision->dev)
+		usb_set_interface(usbvision->dev, usbvision->iface,
 				    usbvision->iface_alt);
 
 	usbvision_audio_off(usbvision);
 	usbvision->radio = 0;
+	usbvision_check(usbvision, "radio close 3");
 	usbvision->user--;
+	r = usbvision->remove_pending;
 	mutex_unlock(&usbvision->v4l2_lock);
 
-	if (usbvision->remove_pending) {
+	if (r) {
 		printk(KERN_INFO "%s: Final disconnect\n", __func__);
 		v4l2_fh_release(file);
 		usbvision_release(usbvision);
@@ -1233,10 +1279,13 @@ static void usbvision_vdev_init(struct u
 static void usbvision_unregister_video(struct usb_usbvision *usbvision)
 {
 	/* Radio Device: */
+	usbvision_check(usbvision, "unregister video");
 	if (video_is_registered(&usbvision->rdev)) {
 		PDEBUG(DBG_PROBE, "unregister %s [v4l2]",
 		       video_device_node_name(&usbvision->rdev));
+		dev_info(&usbvision->rdev.dev, "Unregister\n");
 		video_unregister_device(&usbvision->rdev);
+		printk(KERN_INFO "Unregister done\n");
 	}
 
 	/* Video Device: */
@@ -1283,6 +1332,7 @@ static int usbvision_register_video(stru
 		       usbvision->nr, video_device_node_name(&usbvision->rdev));
 	}
 	/* all done */
+	usbvision_check(usbvision, "register video");
 	return 0;
 
  err_exit:
@@ -1346,6 +1396,7 @@ static void usbvision_release(struct usb
 {
 	PDEBUG(DBG_PROBE, "");
 
+	usbvision_check(usbvision, "release");
 	usbvision->initialized = 0;
 
 	usbvision_remove_sysfs(&usbvision->vdev);
@@ -1551,6 +1602,7 @@ err_usb:
 static void usbvision_disconnect(struct usb_interface *intf)
 {
 	struct usb_usbvision *usbvision = to_usbvision(usb_get_intfdata(intf));
+	int u;
 
 	PDEBUG(DBG_PROBE, "");
 
@@ -1560,6 +1612,7 @@ static void usbvision_disconnect(struct
 	}
 
 	mutex_lock(&usbvision->v4l2_lock);
+	usbvision_check(usbvision, "disconnect 1");
 
 	/* At this time we ask to cancel outstanding URBs */
 	usbvision_stop_isoc(usbvision);
@@ -1567,13 +1620,15 @@ static void usbvision_disconnect(struct
 	v4l2_device_disconnect(&usbvision->v4l2_dev);
 	usbvision_i2c_unregister(usbvision);
 	usbvision->remove_pending = 1;	/* Now all ISO data will be ignored */
+	u = usbvision->user;
 
 	usb_put_dev(usbvision->dev);
 	usbvision->dev = NULL;	/* USB device is no more */
 
+	usbvision_check(usbvision, "disconnect 2");
 	mutex_unlock(&usbvision->v4l2_lock);
 
-	if (usbvision->user) {
+	if (u) {
 		printk(KERN_INFO "%s: In use, disconnect pending\n",
 		       __func__);
 		wake_up_interruptible(&usbvision->wait_frame);