vidioc-subdev-enum-frame-size.rst

.. -*- 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
========

.. c: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:

.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}|

.. 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.