1 files changed, 38 insertions, 20 deletions

diff --git a/drivers/media/video/v4l2-device.c b/drivers/media/video/v4l2-device.c
index 8a4b74f3129f..94aa485ade52 100644
--- a/drivers/media/video/v4l2-device.c
+++ b/drivers/media/video/v4l2-device.c
@@ -26,48 +26,66 @@
 
 int v4l2_device_register(struct device *dev, struct v4l2_device *v4l2_dev)
 {
-        if (dev == NULL || v4l2_dev == NULL)
+        if (v4l2_dev == NULL)
                 return -EINVAL;
-        /* Warn if we apparently re-register a device */
-        WARN_ON(dev_get_drvdata(dev) != NULL);
+
         INIT_LIST_HEAD(&v4l2_dev->subdevs);
         spin_lock_init(&v4l2_dev->lock);
         v4l2_dev->dev = dev;
-        snprintf(v4l2_dev->name, sizeof(v4l2_dev->name), "%s %s",
+        if (dev == NULL) {
+                /* If dev == NULL, then name must be filled in by the caller */
+                WARN_ON(!v4l2_dev->name[0]);
+                return 0;
+        }
+
+        /* Set name to driver name + device name if it is empty. */
+        if (!v4l2_dev->name[0])
+                snprintf(v4l2_dev->name, sizeof(v4l2_dev->name), "%s %s",
                         dev->driver->name, dev_name(dev));
+        if (dev_get_drvdata(dev))
+                v4l2_warn(v4l2_dev, "Non-NULL drvdata on register\n");
         dev_set_drvdata(dev, v4l2_dev);
         return 0;
 }
 EXPORT_SYMBOL_GPL(v4l2_device_register);
 
+void v4l2_device_disconnect(struct v4l2_device *v4l2_dev)
+{
+        if (v4l2_dev->dev) {
+                dev_set_drvdata(v4l2_dev->dev, NULL);
+                v4l2_dev->dev = NULL;
+        }
+}
+EXPORT_SYMBOL_GPL(v4l2_device_disconnect);
+
 void v4l2_device_unregister(struct v4l2_device *v4l2_dev)
 {
         struct v4l2_subdev *sd, *next;
 
-        if (v4l2_dev == NULL || v4l2_dev->dev == NULL)
+        if (v4l2_dev == NULL)
                 return;
-        dev_set_drvdata(v4l2_dev->dev, NULL);
-        /* unregister subdevs */
+        v4l2_device_disconnect(v4l2_dev);
+
+        /* Unregister subdevs */
         list_for_each_entry_safe(sd, next, &v4l2_dev->subdevs, list)
                 v4l2_device_unregister_subdev(sd);
-
-        v4l2_dev->dev = NULL;
 }
 EXPORT_SYMBOL_GPL(v4l2_device_unregister);
 
-int v4l2_device_register_subdev(struct v4l2_device *dev, struct v4l2_subdev *sd)
+int v4l2_device_register_subdev(struct v4l2_device *v4l2_dev,
+                                                struct v4l2_subdev *sd)
 {
         /* Check for valid input */
-        if (dev == NULL || sd == NULL || !sd->name[0])
+        if (v4l2_dev == NULL || sd == NULL || !sd->name[0])
                 return -EINVAL;
         /* Warn if we apparently re-register a subdev */
-        WARN_ON(sd->dev != NULL);
+        WARN_ON(sd->v4l2_dev != NULL);
         if (!try_module_get(sd->owner))
                 return -ENODEV;
-        sd->dev = dev;
-        spin_lock(&dev->lock);
-        list_add_tail(&sd->list, &dev->subdevs);
-        spin_unlock(&dev->lock);
+        sd->v4l2_dev = v4l2_dev;
+        spin_lock(&v4l2_dev->lock);
+        list_add_tail(&sd->list, &v4l2_dev->subdevs);
+        spin_unlock(&v4l2_dev->lock);
         return 0;
 }
 EXPORT_SYMBOL_GPL(v4l2_device_register_subdev);
@@ -75,12 +93,12 @@ EXPORT_SYMBOL_GPL(v4l2_device_register_subdev);
 void v4l2_device_unregister_subdev(struct v4l2_subdev *sd)
 {
         /* return if it isn't registered */
-        if (sd == NULL || sd->dev == NULL)
+        if (sd == NULL || sd->v4l2_dev == NULL)
                 return;
-        spin_lock(&sd->dev->lock);
+        spin_lock(&sd->v4l2_dev->lock);
         list_del(&sd->list);
-        spin_unlock(&sd->dev->lock);
-        sd->dev = NULL;
+        spin_unlock(&sd->v4l2_dev->lock);
+        sd->v4l2_dev = NULL;
         module_put(sd->owner);
 }
 EXPORT_SYMBOL_GPL(v4l2_device_unregister_subdev);