1 files changed, 18 insertions, 13 deletions

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