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.. -*- coding: utf-8; mode: rst -*-
.. _VIDIOC_SUBDEV_ENUM_FRAME_SIZE:
***********************************
ioctl VIDIOC_SUBDEV_ENUM_FRAME_SIZE
***********************************
Name
====
VIDIOC_SUBDEV_ENUM_FRAME_SIZE - Enumerate media bus frame sizes
Synopsis
========
.. cpp:function:: int ioctl( int fd, int request, struct v4l2_subdev_frame_size_enum * argp )
Arguments
=========
``fd``
File descriptor returned by :ref:`open() <func-open>`.
``request``
VIDIOC_SUBDEV_ENUM_FRAME_SIZE
``argp``
Description
===========
This ioctl allows applications to enumerate all frame sizes supported by
a sub-device on the given pad for the given media bus format. Supported
formats can be retrieved with the
:ref:`VIDIOC_SUBDEV_ENUM_MBUS_CODE`
ioctl.
To enumerate frame sizes applications initialize the ``pad``, ``which``
, ``code`` and ``index`` fields of the struct
:ref:`v4l2_subdev_mbus_code_enum <v4l2-subdev-mbus-code-enum>` and
call the :ref:`VIDIOC_SUBDEV_ENUM_FRAME_SIZE` ioctl with a pointer to the
structure. Drivers fill the minimum and maximum frame sizes or return an
EINVAL error code if one of the input parameters is 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.
.. _v4l2-subdev-frame-size-enum:
.. flat-table:: struct v4l2_subdev_frame_size_enum
:header-rows: 0
:stub-columns: 0
:widths: 1 1 2
- .. row 1
- __u32
- ``index``
- Number of the format in the enumeration, set by the application.
- .. row 2
- __u32
- ``pad``
- Pad number as reported by the media controller API.
- .. row 3
- __u32
- ``code``
- The media bus format code, as defined in
:ref:`v4l2-mbus-format`.
- .. row 4
- __u32
- ``min_width``
- Minimum frame width, in pixels.
- .. row 5
- __u32
- ``max_width``
- Maximum frame width, in pixels.
- .. row 6
- __u32
- ``min_height``
- Minimum frame height, in pixels.
- .. row 7
- __u32
- ``max_height``
- Maximum frame height, in pixels.
- .. row 8
- __u32
- ``which``
- Frame sizes to be enumerated, from enum
:ref:`v4l2_subdev_format_whence <v4l2-subdev-format-whence>`.
- .. row 9
- __u32
- ``reserved``\ [8]
- 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
:ref:`v4l2_subdev_frame_size_enum <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.
|
