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.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
.. c:namespace:: V4L
.. _VIDIOC_SUBDEV_ENUM_FRAME_SIZE:
***********************************
ioctl VIDIOC_SUBDEV_ENUM_FRAME_SIZE
***********************************
Name
====
VIDIOC_SUBDEV_ENUM_FRAME_SIZE - Enumerate media bus frame sizes
Synopsis
========
.. c:macro:: VIDIOC_SUBDEV_ENUM_FRAME_SIZE
``int ioctl(int fd, VIDIOC_SUBDEV_ENUM_FRAME_SIZE, struct v4l2_subdev_frame_size_enum * argp)``
Arguments
=========
``fd``
File descriptor returned by :c:func:`open()`.
``argp``
Pointer to struct :c:type:`v4l2_subdev_frame_size_enum`.
Description
===========
This ioctl allows applications to access the enumeration of frame sizes
supported by a sub-device on the specified pad
for the specified media bus format.
Supported formats can be retrieved with the
:ref:`VIDIOC_SUBDEV_ENUM_MBUS_CODE`
ioctl.
The enumerations are defined by the driver, and indexed using the ``index`` field
of the struct :c:type:`v4l2_subdev_frame_size_enum`.
Each pair of ``pad`` and ``code`` correspond to a separate enumeration.
Each enumeration starts with the ``index`` of 0, and
the lowest invalid index marks the end of the enumeration.
Therefore, to enumerate frame sizes allowed on the specified pad
and using the specified mbus format, initialize the
``pad``, ``which``, and ``code`` fields to desired values,
and set ``index`` to 0.
Then call the :ref:`VIDIOC_SUBDEV_ENUM_FRAME_SIZE` ioctl with a pointer to the
structure.
A successful call will return with minimum and maximum frame sizes filled in.
Repeat with increasing ``index`` until ``EINVAL`` is received.
``EINVAL`` means that either no more entries are available in the enumeration,
or that an input parameter was invalid.
Sub-devices that only support discrete frame sizes (such as most
sensors) will return one or more frame sizes with identical minimum and
maximum values.
Not all possible sizes in given [minimum, maximum] ranges need to be
supported. For instance, a scaler that uses a fixed-point scaling ratio
might not be able to produce every frame size between the minimum and
maximum values. Applications must use the
:ref:`VIDIOC_SUBDEV_S_FMT <VIDIOC_SUBDEV_G_FMT>` ioctl to try the
sub-device for an exact supported frame size.
Available frame sizes may depend on the current 'try' formats at other
pads of the sub-device, as well as on the current active links and the
current values of V4L2 controls. See
:ref:`VIDIOC_SUBDEV_G_FMT` for more
information about try formats.
.. c:type:: v4l2_subdev_frame_size_enum
.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.5cm}|
.. flat-table:: struct v4l2_subdev_frame_size_enum
:header-rows: 0
:stub-columns: 0
:widths: 1 1 2
* - __u32
- ``index``
- Index of the frame size in the enumeration belonging to the given pad
and format. Filled in by the application.
* - __u32
- ``pad``
- Pad number as reported by the media controller API.
Filled in by the application.
* - __u32
- ``code``
- The media bus format code, as defined in
:ref:`v4l2-mbus-format`. Filled in by the application.
* - __u32
- ``min_width``
- Minimum frame width, in pixels. Filled in by the driver.
* - __u32
- ``max_width``
- Maximum frame width, in pixels. Filled in by the driver.
* - __u32
- ``min_height``
- Minimum frame height, in pixels. Filled in by the driver.
* - __u32
- ``max_height``
- Maximum frame height, in pixels. Filled in by the driver.
* - __u32
- ``which``
- Frame sizes to be enumerated, from enum
:ref:`v4l2_subdev_format_whence <v4l2-subdev-format-whence>`.
* - __u32
- ``stream``
- Stream identifier.
* - __u32
- ``reserved``\ [7]
- Reserved for future extensions. Applications and drivers must set
the array to zero.
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
The struct
:c:type:`v4l2_subdev_frame_size_enum`
``pad`` references a non-existing pad, the ``code`` is invalid for
the given pad or the ``index`` field is out of bounds.
|
