3 files changed, 48 insertions, 30 deletions

diff --git a/Documentation/video4linux/v4l2-framework.txt b/Documentation/video4linux/v4l2-framework.txt
index 48cdf86248cb..e1620e2a38ff 100644
--- a/Documentation/video4linux/v4l2-framework.txt
+++ b/Documentation/video4linux/v4l2-framework.txt
@@ -84,12 +84,14 @@ You must register the device instance:
         v4l2_device_register(struct device *dev, struct v4l2_device *v4l2_dev);
 
 Registration will initialize the v4l2_device struct and link dev->driver_data
-to v4l2_dev. Registration will also set v4l2_dev->name to a value derived from
-dev (driver name followed by the bus_id, to be precise). You may change the
-name after registration if you want.
+to v4l2_dev. If v4l2_dev->name is empty then it will be set to a value derived
+from dev (driver name followed by the bus_id, to be precise). If you set it
+up before calling v4l2_device_register then it will be untouched. If dev is
+NULL, then you *must* setup v4l2_dev->name before calling v4l2_device_register.
 
 The first 'dev' argument is normally the struct device pointer of a pci_dev,
-usb_device or platform_device.
+usb_device or platform_device. It is rare for dev to be NULL, but it happens
+with ISA devices, for example.
 
 You unregister with:
 
diff --git a/drivers/media/video/v4l2-device.c b/drivers/media/video/v4l2-device.c
index 8a4b74f3129f..3330ffb7d010 100644
--- a/drivers/media/video/v4l2-device.c
+++ b/drivers/media/video/v4l2-device.c
@@ -26,15 +26,24 @@
 
 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;
 }
@@ -44,10 +53,11 @@ 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 */
+        if (v4l2_dev->dev)
+                dev_set_drvdata(v4l2_dev->dev, NULL);
+        /* Unregister subdevs */
         list_for_each_entry_safe(sd, next, &v4l2_dev->subdevs, list)
                 v4l2_device_unregister_subdev(sd);
 
@@ -55,19 +65,20 @@ void v4l2_device_unregister(struct v4l2_device *v4l2_dev)
 }
 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);
         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->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);
diff --git a/include/media/v4l2-device.h b/include/media/v4l2-device.h
index 55e41afd95ef..5d7146dc2913 100644
--- a/include/media/v4l2-device.h
+++ b/include/media/v4l2-device.h
@@ -33,7 +33,9 @@
 #define V4L2_DEVICE_NAME_SIZE (BUS_ID_SIZE + 16)
 
 struct v4l2_device {
-        /* dev->driver_data points to this struct */
+        /* dev->driver_data points to this struct.
+           Note: dev might be NULL if there is no parent device
+           as is the case with e.g. ISA devices. */
         struct device *dev;
         /* used to keep track of the registered subdevs */
         struct list_head subdevs;
@@ -44,7 +46,9 @@ struct v4l2_device {
         char name[V4L2_DEVICE_NAME_SIZE];
 };
 
-/* Initialize v4l2_dev and make dev->driver_data point to v4l2_dev */
+/* Initialize v4l2_dev and make dev->driver_data point to v4l2_dev.
+   dev may be NULL in rare cases (ISA devices). In that case you
+   must fill in the v4l2_dev->name field before calling this function. */
 int __must_check v4l2_device_register(struct device *dev, struct v4l2_device *v4l2_dev);
 /* Set v4l2_dev->dev->driver_data to NULL and unregister all sub-devices */
 void v4l2_device_unregister(struct v4l2_device *v4l2_dev);
@@ -52,23 +56,24 @@ void v4l2_device_unregister(struct v4l2_device *v4l2_dev);
 /* Register a subdev with a v4l2 device. While registered the subdev module
    is marked as in-use. An error is returned if the module is no longer
    loaded when you attempt to register it. */
-int __must_check v4l2_device_register_subdev(struct v4l2_device *dev, struct v4l2_subdev *sd);
+int __must_check v4l2_device_register_subdev(struct v4l2_device *v4l2_dev,
+                                                struct v4l2_subdev *sd);
 /* Unregister a subdev with a v4l2 device. Can also be called if the subdev
    wasn't registered. In that case it will do nothing. */
 void v4l2_device_unregister_subdev(struct v4l2_subdev *sd);
 
 /* Iterate over all subdevs. */
-#define v4l2_device_for_each_subdev(sd, dev)                            \
-        list_for_each_entry(sd, &(dev)->subdevs, list)
+#define v4l2_device_for_each_subdev(sd, v4l2_dev)                       \
+        list_for_each_entry(sd, &(v4l2_dev)->subdevs, list)
 
 /* Call the specified callback for all subdevs matching the condition.
    Ignore any errors. Note that you cannot add or delete a subdev
    while walking the subdevs list. */
-#define __v4l2_device_call_subdevs(dev, cond, o, f, args...)            \
+#define __v4l2_device_call_subdevs(v4l2_dev, cond, o, f, args...)       \
         do {                                                            \
                 struct v4l2_subdev *sd;                                 \
                                                                         \
-                list_for_each_entry(sd, &(dev)->subdevs, list)          \
+                list_for_each_entry(sd, &(v4l2_dev)->subdevs, list)     \
                         if ((cond) && sd->ops->o && sd->ops->o->f)      \
                                 sd->ops->o->f(sd , ##args);             \
         } while (0)
@@ -77,12 +82,12 @@ void v4l2_device_unregister_subdev(struct v4l2_subdev *sd);
    If the callback returns an error other than 0 or -ENOIOCTLCMD, then
    return with that error code. Note that you cannot add or delete a
    subdev while walking the subdevs list. */
-#define __v4l2_device_call_subdevs_until_err(dev, cond, o, f, args...)  \
+#define __v4l2_device_call_subdevs_until_err(v4l2_dev, cond, o, f, args...) \
 ({                                                                      \
         struct v4l2_subdev *sd;                                         \
         long err = 0;                                                   \
                                                                         \
-        list_for_each_entry(sd, &(dev)->subdevs, list) {                \
+        list_for_each_entry(sd, &(v4l2_dev)->subdevs, list) {           \
                 if ((cond) && sd->ops->o && sd->ops->o->f)              \
                         err = sd->ops->o->f(sd , ##args);               \
                 if (err && err != -ENOIOCTLCMD)                         \
@@ -94,16 +99,16 @@ void v4l2_device_unregister_subdev(struct v4l2_subdev *sd);
 /* Call the specified callback for all subdevs matching grp_id (if 0, then
    match them all). Ignore any errors. Note that you cannot add or delete
    a subdev while walking the subdevs list. */
-#define v4l2_device_call_all(dev, grpid, o, f, args...)                 \
-        __v4l2_device_call_subdevs(dev,                                 \
+#define v4l2_device_call_all(v4l2_dev, grpid, o, f, args...)            \
+        __v4l2_device_call_subdevs(v4l2_dev,                            \
                         !(grpid) || sd->grp_id == (grpid), o, f , ##args)
 
 /* Call the specified callback for all subdevs matching grp_id (if 0, then
    match them all). If the callback returns an error other than 0 or
    -ENOIOCTLCMD, then return with that error code. Note that you cannot
    add or delete a subdev while walking the subdevs list. */
-#define v4l2_device_call_until_err(dev, grpid, o, f, args...)           \
-        __v4l2_device_call_subdevs_until_err(dev,                       \
+#define v4l2_device_call_until_err(v4l2_dev, grpid, o, f, args...)      \
+        __v4l2_device_call_subdevs_until_err(v4l2_dev,                  \
                        !(grpid) || sd->grp_id == (grpid), o, f , ##args)
 
 #endif