20ea6adbf1
Build system: x86_64 Build-tested: bcm2708, bcm2709, bcm2710, bcm2711 Run-tested: bcm2708/RPiB+, bcm2709/RPi3B, bcm2710/RPi3B, bcm2711/RPi4B Signed-off-by: Marty Jones <mj8263788@gmail.com> Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
52 lines
2.3 KiB
Diff
52 lines
2.3 KiB
Diff
From 1ef126fb69d37c6958a0b945365e532b500d43bd Mon Sep 17 00:00:00 2001
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From: Hans Verkuil <hverkuil-cisco@xs4all.nl>
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Date: Wed, 14 Apr 2021 15:01:16 +0200
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Subject: [PATCH] videodev2.h: add V4L2_CTRL_FLAG_DYNAMIC_ARRAY
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Add a new flag that indicates that this control is a dynamically sized
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array. Also document this flag.
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Currently dynamically sized arrays are limited to one dimensional arrays,
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but that might change in the future if there is a need for it.
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The initial use-case of dynamic arrays are stateless codecs. A frame
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can be divided in many slices, so you want to provide an array containing
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slice information for each slice. Typically the number of slices is small,
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but the standard allow for hundreds or thousands of slices. Dynamic arrays
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are a good solution since sizing the array for the worst case would waste
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substantial amounts of memory.
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Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
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(cherry picked from commit c095ad310b223b9de38d491c9f66533d05586b45)
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---
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.../userspace-api/media/v4l/vidioc-queryctrl.rst | 8 ++++++++
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include/uapi/linux/videodev2.h | 1 +
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2 files changed, 9 insertions(+)
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--- a/Documentation/userspace-api/media/v4l/vidioc-queryctrl.rst
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+++ b/Documentation/userspace-api/media/v4l/vidioc-queryctrl.rst
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@@ -607,6 +607,14 @@ See also the examples in :ref:`control`.
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``V4L2_CTRL_FLAG_GRABBED`` flag when buffers are allocated or
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streaming is in progress since most drivers do not support changing
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the format in that case.
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+ * - ``V4L2_CTRL_FLAG_DYNAMIC_ARRAY``
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+ - 0x0800
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+ - This control is a dynamically sized 1-dimensional array. It
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+ behaves the same as a regular array, except that the number
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+ of elements as reported by the ``elems`` field is between 1 and
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+ ``dims[0]``. So setting the control with a differently sized
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+ array will change the ``elems`` field when the control is
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+ queried afterwards.
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Return Value
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============
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--- a/include/uapi/linux/videodev2.h
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+++ b/include/uapi/linux/videodev2.h
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@@ -1882,6 +1882,7 @@ struct v4l2_querymenu {
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#define V4L2_CTRL_FLAG_HAS_PAYLOAD 0x0100
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#define V4L2_CTRL_FLAG_EXECUTE_ON_WRITE 0x0200
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#define V4L2_CTRL_FLAG_MODIFY_LAYOUT 0x0400
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+#define V4L2_CTRL_FLAG_DYNAMIC_ARRAY 0x0800
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/* Query flags, to be ORed with the control ID */
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#define V4L2_CTRL_FLAG_NEXT_CTRL 0x80000000
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