Adding upstream version 5.10.209.upstream/5.10.209upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 190 insertions, 0 deletions

diff --git a/Documentation/userspace-api/media/v4l/vidioc-g-selection.rst b/Documentation/userspace-api/media/v4l/vidioc-g-selection.rst
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+.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
+.. c:namespace:: V4L
+
+.. _VIDIOC_G_SELECTION:
+
+********************************************
+ioctl VIDIOC_G_SELECTION, VIDIOC_S_SELECTION
+********************************************
+
+Name
+====
+
+VIDIOC_G_SELECTION - VIDIOC_S_SELECTION - Get or set one of the selection rectangles
+
+Synopsis
+========
+
+.. c:macro:: VIDIOC_G_SELECTION
+
+``int ioctl(int fd, VIDIOC_G_SELECTION, struct v4l2_selection *argp)``
+
+.. c:macro:: VIDIOC_S_SELECTION
+
+``int ioctl(int fd, VIDIOC_S_SELECTION, struct v4l2_selection *argp)``
+
+Arguments
+=========
+
+``fd``
+    File descriptor returned by :c:func:`open()`.
+
+``argp``
+    Pointer to struct :c:type:`v4l2_selection`.
+
+Description
+===========
+
+The ioctls are used to query and configure selection rectangles.
+
+To query the cropping (composing) rectangle set struct
+:c:type:`v4l2_selection` ``type`` field to the
+respective buffer type. The next step is setting the
+value of struct :c:type:`v4l2_selection` ``target``
+field to ``V4L2_SEL_TGT_CROP`` (``V4L2_SEL_TGT_COMPOSE``). Please refer
+to table :ref:`v4l2-selections-common` or :ref:`selection-api` for
+additional targets. The ``flags`` and ``reserved`` fields of struct
+:c:type:`v4l2_selection` are ignored and they must be
+filled with zeros. The driver fills the rest of the structure or returns
+EINVAL error code if incorrect buffer type or target was used. If
+cropping (composing) is not supported then the active rectangle is not
+mutable and it is always equal to the bounds rectangle. Finally, the
+struct :c:type:`v4l2_rect` ``r`` rectangle is filled with
+the current cropping (composing) coordinates. The coordinates are
+expressed in driver-dependent units. The only exception are rectangles
+for images in raw formats, whose coordinates are always expressed in
+pixels.
+
+To change the cropping (composing) rectangle set the struct
+:c:type:`v4l2_selection` ``type`` field to the
+respective buffer type. The next step is setting the
+value of struct :c:type:`v4l2_selection` ``target`` to
+``V4L2_SEL_TGT_CROP`` (``V4L2_SEL_TGT_COMPOSE``). Please refer to table
+:ref:`v4l2-selections-common` or :ref:`selection-api` for additional
+targets. The struct :c:type:`v4l2_rect` ``r`` rectangle need
+to be set to the desired active area. Field struct
+:c:type:`v4l2_selection` ``reserved`` is ignored and
+must be filled with zeros. The driver may adjust coordinates of the
+requested rectangle. An application may introduce constraints to control
+rounding behaviour. The struct :c:type:`v4l2_selection`
+``flags`` field must be set to one of the following:
+
+-  ``0`` - The driver can adjust the rectangle size freely and shall
+   choose a crop/compose rectangle as close as possible to the requested
+   one.
+
+-  ``V4L2_SEL_FLAG_GE`` - The driver is not allowed to shrink the
+   rectangle. The original rectangle must lay inside the adjusted one.
+
+-  ``V4L2_SEL_FLAG_LE`` - The driver is not allowed to enlarge the
+   rectangle. The adjusted rectangle must lay inside the original one.
+
+-  ``V4L2_SEL_FLAG_GE | V4L2_SEL_FLAG_LE`` - The driver must choose the
+   size exactly the same as in the requested rectangle.
+
+Please refer to :ref:`sel-const-adjust`.
+
+The driver may have to adjusts the requested dimensions against hardware
+limits and other parts as the pipeline, i.e. the bounds given by the
+capture/output window or TV display. The closest possible values of
+horizontal and vertical offset and sizes are chosen according to
+following priority:
+
+1. Satisfy constraints from struct
+   :c:type:`v4l2_selection` ``flags``.
+
+2. Adjust width, height, left, and top to hardware limits and
+   alignments.
+
+3. Keep center of adjusted rectangle as close as possible to the
+   original one.
+
+4. Keep width and height as close as possible to original ones.
+
+5. Keep horizontal and vertical offset as close as possible to original
+   ones.
+
+On success the struct :c:type:`v4l2_rect` ``r`` field
+contains the adjusted rectangle. When the parameters are unsuitable the
+application may modify the cropping (composing) or image parameters and
+repeat the cycle until satisfactory parameters have been negotiated. If
+constraints flags have to be violated at then ``ERANGE`` is returned. The
+error indicates that *there exist no rectangle* that satisfies the
+constraints.
+
+Selection targets and flags are documented in
+:ref:`v4l2-selections-common`.
+
+.. _sel-const-adjust:
+
+.. kernel-figure::  constraints.svg
+    :alt:    constraints.svg
+    :align:  center
+
+    Size adjustments with constraint flags.
+
+    Behaviour of rectangle adjustment for different constraint flags.
+
+
+
+.. c:type:: v4l2_selection
+
+.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}|
+
+.. flat-table:: struct v4l2_selection
+    :header-rows:  0
+    :stub-columns: 0
+    :widths:       1 1 2
+
+    * - __u32
+      - ``type``
+      - Type of the buffer (from enum
+	:c:type:`v4l2_buf_type`).
+    * - __u32
+      - ``target``
+      - Used to select between
+	:ref:`cropping and composing rectangles <v4l2-selections-common>`.
+    * - __u32
+      - ``flags``
+      - Flags controlling the selection rectangle adjustments, refer to
+	:ref:`selection flags <v4l2-selection-flags>`.
+    * - struct :c:type:`v4l2_rect`
+      - ``r``
+      - The selection rectangle.
+    * - __u32
+      - ``reserved[9]``
+      - Reserved fields for future use. Drivers and applications must zero
+	this array.
+
+.. note::
+   Unfortunately in the case of multiplanar buffer types
+   (``V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE`` and ``V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE``)
+   this API was messed up with regards to how the :c:type:`v4l2_selection` ``type`` field
+   should be filled in. Some drivers only accepted the ``_MPLANE`` buffer type while
+   other drivers only accepted a non-multiplanar buffer type (i.e. without the
+   ``_MPLANE`` at the end).
+
+   Starting with kernel 4.13 both variations are allowed.
+
+Return Value
+============
+
+On success 0 is returned, on error -1 and the ``errno`` variable is set
+appropriately. The generic error codes are described at the
+:ref:`Generic Error Codes <gen-errors>` chapter.
+
+EINVAL
+    Given buffer type ``type`` or the selection target ``target`` is not
+    supported, or the ``flags`` argument is not valid.
+
+ERANGE
+    It is not possible to adjust struct :c:type:`v4l2_rect`
+    ``r`` rectangle to satisfy all constraints given in the ``flags``
+    argument.
+
+ENODATA
+    Selection is not supported for this input or output.
+
+EBUSY
+    It is not possible to apply change of the selection rectangle at the
+    moment. Usually because streaming is in progress.