V4L/DVB: v4l: Add a v4l2_subdev host private data field

[mv-sheeva.git] / Documentation / video4linux / v4l2-framework.txt

diff --git a/Documentation/video4linux/v4l2-framework.txt b/Documentation/video4linux/v4l2-framework.txt
index e831aaca66f84ae25fcfdda50a94847251edc644..f5fdb395287f734857a1c117bcd0c4a4edac527e 100644 (file)
--- a/Documentation/video4linux/v4l2-framework.txt
+++ b/Documentation/video4linux/v4l2-framework.txt
@@ -192,6 +192,11 @@ You also need a way to go from the low-level struct to v4l2_subdev. For the
 common i2c_client struct the i2c_set_clientdata() call is used to store a
 v4l2_subdev pointer, for other busses you may have to use other methods.
 
+Bridges might also need to store per-subdev private data, such as a pointer to
+bridge-specific per-subdev private data. The v4l2_subdev structure provides
+host private data for that purpose that can be accessed with
+v4l2_get_subdev_hostdata() and v4l2_set_subdev_hostdata().
+
 From the bridge driver perspective you load the sub-device module and somehow
 obtain the v4l2_subdev pointer. For i2c devices this is easy: you call
 i2c_get_clientdata(). For other busses something similar needs to be done.