Adding upstream version 6.1.76.upstream/6.1.76upstream

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

1 files changed, 186 insertions, 0 deletions

diff --git a/Documentation/userspace-api/media/v4l/vidioc-enum-frameintervals.rst b/Documentation/userspace-api/media/v4l/vidioc-enum-frameintervals.rst
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+.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
+.. c:namespace:: V4L
+
+.. _VIDIOC_ENUM_FRAMEINTERVALS:
+
+********************************
+ioctl VIDIOC_ENUM_FRAMEINTERVALS
+********************************
+
+Name
+====
+
+VIDIOC_ENUM_FRAMEINTERVALS - Enumerate frame intervals
+
+Synopsis
+========
+
+.. c:macro:: VIDIOC_ENUM_FRAMEINTERVALS
+
+``int ioctl(int fd, VIDIOC_ENUM_FRAMEINTERVALS, struct v4l2_frmivalenum *argp)``
+
+Arguments
+=========
+
+``fd``
+    File descriptor returned by :c:func:`open()`.
+
+``argp``
+    Pointer to struct :c:type:`v4l2_frmivalenum`
+    that contains a pixel format and size and receives a frame interval.
+
+Description
+===========
+
+This ioctl allows applications to enumerate all frame intervals that the
+device supports for the given pixel format and frame size.
+
+The supported pixel formats and frame sizes can be obtained by using the
+:ref:`VIDIOC_ENUM_FMT` and
+:ref:`VIDIOC_ENUM_FRAMESIZES` functions.
+
+The return value and the content of the ``v4l2_frmivalenum.type`` field
+depend on the type of frame intervals the device supports. Here are the
+semantics of the function for the different cases:
+
+-  **Discrete:** The function returns success if the given index value
+   (zero-based) is valid. The application should increase the index by
+   one for each call until ``EINVAL`` is returned. The
+   `v4l2_frmivalenum.type` field is set to
+   `V4L2_FRMIVAL_TYPE_DISCRETE` by the driver. Of the union only
+   the `discrete` member is valid.
+
+-  **Step-wise:** The function returns success if the given index value
+   is zero and ``EINVAL`` for any other index value. The
+   ``v4l2_frmivalenum.type`` field is set to
+   ``V4L2_FRMIVAL_TYPE_STEPWISE`` by the driver. Of the union only the
+   ``stepwise`` member is valid.
+
+-  **Continuous:** This is a special case of the step-wise type above.
+   The function returns success if the given index value is zero and
+   ``EINVAL`` for any other index value. The ``v4l2_frmivalenum.type``
+   field is set to ``V4L2_FRMIVAL_TYPE_CONTINUOUS`` by the driver. Of
+   the union only the ``stepwise`` member is valid and the ``step``
+   value is set to 1.
+
+When the application calls the function with index zero, it must check
+the ``type`` field to determine the type of frame interval enumeration
+the device supports. Only for the ``V4L2_FRMIVAL_TYPE_DISCRETE`` type
+does it make sense to increase the index value to receive more frame
+intervals.
+
+.. note::
+
+   The order in which the frame intervals are returned has no
+   special meaning. In particular does it not say anything about potential
+   default frame intervals.
+
+Applications can assume that the enumeration data does not change
+without any interaction from the application itself. This means that the
+enumeration data is consistent if the application does not perform any
+other ioctl calls while it runs the frame interval enumeration.
+
+.. note::
+
+   **Frame intervals and frame rates:** The V4L2 API uses frame
+   intervals instead of frame rates. Given the frame interval the frame
+   rate can be computed as follows:
+
+   ::
+
+       frame_rate = 1 / frame_interval
+
+Structs
+=======
+
+In the structs below, *IN* denotes a value that has to be filled in by
+the application, *OUT* denotes values that the driver fills in. The
+application should zero out all members except for the *IN* fields.
+
+.. c:type:: v4l2_frmival_stepwise
+
+.. flat-table:: struct v4l2_frmival_stepwise
+    :header-rows:  0
+    :stub-columns: 0
+    :widths:       1 1 2
+
+    * - struct :c:type:`v4l2_fract`
+      - ``min``
+      - Minimum frame interval [s].
+    * - struct :c:type:`v4l2_fract`
+      - ``max``
+      - Maximum frame interval [s].
+    * - struct :c:type:`v4l2_fract`
+      - ``step``
+      - Frame interval step size [s].
+
+
+.. c:type:: v4l2_frmivalenum
+
+.. tabularcolumns:: |p{4.9cm}|p{3.3cm}|p{9.1cm}|
+
+.. flat-table:: struct v4l2_frmivalenum
+    :header-rows:  0
+    :stub-columns: 0
+
+    * - __u32
+      - ``index``
+      - IN: Index of the given frame interval in the enumeration.
+    * - __u32
+      - ``pixel_format``
+      - IN: Pixel format for which the frame intervals are enumerated.
+    * - __u32
+      - ``width``
+      - IN: Frame width for which the frame intervals are enumerated.
+    * - __u32
+      - ``height``
+      - IN: Frame height for which the frame intervals are enumerated.
+    * - __u32
+      - ``type``
+      - OUT: Frame interval type the device supports.
+    * - union {
+      - (anonymous)
+      - OUT: Frame interval with the given index.
+    * - struct :c:type:`v4l2_fract`
+      - ``discrete``
+      - Frame interval [s].
+    * - struct :c:type:`v4l2_frmival_stepwise`
+      - ``stepwise``
+      -
+    * - }
+      -
+      -
+    * - __u32
+      - ``reserved[2]``
+      - Reserved space for future use. Must be zeroed by drivers and
+	applications.
+
+
+Enums
+=====
+
+.. c:type:: v4l2_frmivaltypes
+
+.. tabularcolumns:: |p{6.6cm}|p{2.2cm}|p{8.5cm}|
+
+.. flat-table:: enum v4l2_frmivaltypes
+    :header-rows:  0
+    :stub-columns: 0
+    :widths:       3 1 4
+
+    * - ``V4L2_FRMIVAL_TYPE_DISCRETE``
+      - 1
+      - Discrete frame interval.
+    * - ``V4L2_FRMIVAL_TYPE_CONTINUOUS``
+      - 2
+      - Continuous frame interval.
+    * - ``V4L2_FRMIVAL_TYPE_STEPWISE``
+      - 3
+      - Step-wise defined frame interval.
+
+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.