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| author | Hans Verkuil <hverkuil-cisco@xs4all.nl> | 2022-07-08 17:21:40 +0100 |
|---|---|---|
| committer | Mauro Carvalho Chehab <mchehab@kernel.org> | 2022-07-15 16:17:31 +0100 |
| commit | 64fe675e999c2c7d753ecaaa1349693c59ce6c11 (patch) | |
| tree | dd3e899b19fef36aae1029dcf6a150bee5c1c068 | |
| parent | b228cf38f0b72d797fab60386da7ee935e033aac (diff) | |
| download | lwn-64fe675e999c2c7d753ecaaa1349693c59ce6c11.tar.gz lwn-64fe675e999c2c7d753ecaaa1349693c59ce6c11.zip | |
media: videodev2.h: add V4L2_CTRL_FLAG_DYNAMIC_ARRAY
Add a new flag that indicates that this control is a dynamically sized
array. Also document this flag.
Currently dynamically sized arrays are limited to one dimensional arrays,
but that might change in the future if there is a need for it.
The initial use-case of dynamic arrays are stateless codecs. A frame
can be divided in many slices, so you want to provide an array containing
slice information for each slice. Typically the number of slices is small,
but the standard allow for hundreds or thousands of slices. Dynamic arrays
are a good solution since sizing the array for the worst case would waste
substantial amounts of memory.
Acked-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Tested-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
Tested-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
| -rw-r--r-- | Documentation/userspace-api/media/v4l/vidioc-queryctrl.rst | 8 | ||||
| -rw-r--r-- | Documentation/userspace-api/media/videodev2.h.rst.exceptions | 1 | ||||
| -rw-r--r-- | include/uapi/linux/videodev2.h | 1 |
3 files changed, 10 insertions, 0 deletions
diff --git a/Documentation/userspace-api/media/v4l/vidioc-queryctrl.rst b/Documentation/userspace-api/media/v4l/vidioc-queryctrl.rst index 88f630252d98..a20dfa2a933b 100644 --- a/Documentation/userspace-api/media/v4l/vidioc-queryctrl.rst +++ b/Documentation/userspace-api/media/v4l/vidioc-queryctrl.rst @@ -625,6 +625,14 @@ See also the examples in :ref:`control`. ``V4L2_CTRL_FLAG_GRABBED`` flag when buffers are allocated or streaming is in progress since most drivers do not support changing the format in that case. + * - ``V4L2_CTRL_FLAG_DYNAMIC_ARRAY`` + - 0x0800 + - This control is a dynamically sized 1-dimensional array. It + behaves the same as a regular array, except that the number + of elements as reported by the ``elems`` field is between 1 and + ``dims[0]``. So setting the control with a differently sized + array will change the ``elems`` field when the control is + queried afterwards. Return Value ============ diff --git a/Documentation/userspace-api/media/videodev2.h.rst.exceptions b/Documentation/userspace-api/media/videodev2.h.rst.exceptions index 9cbb7a0c354a..0b91200776f8 100644 --- a/Documentation/userspace-api/media/videodev2.h.rst.exceptions +++ b/Documentation/userspace-api/media/videodev2.h.rst.exceptions @@ -379,6 +379,7 @@ replace define V4L2_CTRL_FLAG_VOLATILE control-flags replace define V4L2_CTRL_FLAG_HAS_PAYLOAD control-flags replace define V4L2_CTRL_FLAG_EXECUTE_ON_WRITE control-flags replace define V4L2_CTRL_FLAG_MODIFY_LAYOUT control-flags +replace define V4L2_CTRL_FLAG_DYNAMIC_ARRAY control-flags replace define V4L2_CTRL_FLAG_NEXT_CTRL control replace define V4L2_CTRL_FLAG_NEXT_COMPOUND control diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h index e32b9e25258d..87ebc6baafb6 100644 --- a/include/uapi/linux/videodev2.h +++ b/include/uapi/linux/videodev2.h @@ -1914,6 +1914,7 @@ struct v4l2_querymenu { #define V4L2_CTRL_FLAG_HAS_PAYLOAD 0x0100 #define V4L2_CTRL_FLAG_EXECUTE_ON_WRITE 0x0200 #define V4L2_CTRL_FLAG_MODIFY_LAYOUT 0x0400 +#define V4L2_CTRL_FLAG_DYNAMIC_ARRAY 0x0800 /* Query flags, to be ORed with the control ID */ #define V4L2_CTRL_FLAG_NEXT_CTRL 0x80000000 |