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authorSakari Ailus <sakari.ailus@iki.fi>2011-10-11 00:01:25 +0400
committerMauro Carvalho Chehab <mchehab@redhat.com>2012-05-14 15:45:31 +0400
commit8227c92b69688403dee2adf5f399a49539ae5049 (patch)
treeb9f4775e4f9ed99c41aca6cf6334aaef6f861d69 /Documentation
parent48398f932b4ddcc8fa9a890595645cc14f6889a8 (diff)
downloadlinux-8227c92b69688403dee2adf5f399a49539ae5049.tar.xz
[media] v4l: Implement v4l2_subdev_link_validate()
v4l2_subdev_link_validate() is the default op for validating a link. In V4L2 subdev context, it is used to call a pad op which performs the proper link check without much extra work. Signed-off-by: Sakari Ailus <sakari.ailus@iki.fi> Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/video4linux/v4l2-framework.txt12
1 files changed, 12 insertions, 0 deletions
diff --git a/Documentation/video4linux/v4l2-framework.txt b/Documentation/video4linux/v4l2-framework.txt
index 493ffd1b1cf5..fe53177f0d3c 100644
--- a/Documentation/video4linux/v4l2-framework.txt
+++ b/Documentation/video4linux/v4l2-framework.txt
@@ -316,6 +316,18 @@ If the subdev driver intends to process video and integrate with the media
framework, it must implement format related functionality using
v4l2_subdev_pad_ops instead of v4l2_subdev_video_ops.
+In that case, the subdev driver may set the link_validate field to provide
+its own link validation function. The link validation function is called for
+every link in the pipeline where both of the ends of the links are V4L2
+sub-devices. The driver is still responsible for validating the correctness
+of the format configuration between sub-devices and video nodes.
+
+If link_validate op is not set, the default function
+v4l2_subdev_link_validate_default() is used instead. This function ensures
+that width, height and the media bus pixel code are equal on both source and
+sink of the link. Subdev drivers are also free to use this function to
+perform the checks mentioned above in addition to their own checks.
+
A device (bridge) driver needs to register the v4l2_subdev with the
v4l2_device: