diff options
Diffstat (limited to 'Documentation/userspace-api/media/v4l/vidioc-subdev-enum-frame-size.rst')
| -rw-r--r-- | Documentation/userspace-api/media/v4l/vidioc-subdev-enum-frame-size.rst | 125 |
1 files changed, 125 insertions, 0 deletions
diff --git a/Documentation/userspace-api/media/v4l/vidioc-subdev-enum-frame-size.rst b/Documentation/userspace-api/media/v4l/vidioc-subdev-enum-frame-size.rst new file mode 100644 index 000000000000..eb7401991d02 --- /dev/null +++ b/Documentation/userspace-api/media/v4l/vidioc-subdev-enum-frame-size.rst @@ -0,0 +1,125 @@ +.. Permission is granted to copy, distribute and/or modify this +.. document under the terms of the GNU Free Documentation License, +.. Version 1.1 or any later version published by the Free Software +.. Foundation, with no Invariant Sections, no Front-Cover Texts +.. and no Back-Cover Texts. A copy of the license is included at +.. Documentation/userspace-api/media/fdl-appendix.rst. +.. +.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections + +.. _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, VIDIOC_SUBDEV_ENUM_FRAME_SIZE, struct v4l2_subdev_frame_size_enum * argp ) + :name: VIDIOC_SUBDEV_ENUM_FRAME_SIZE + + +Arguments +========= + +``fd`` + File descriptor returned by :ref:`open() <func-open>`. + +``argp`` + Pointer to struct :c:type:`v4l2_subdev_frame_size_enum`. + + +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 +:c:type:`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. + + +.. c:type:: 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 + + * - __u32 + - ``index`` + - Number of the format in the enumeration, set by the application. + * - __u32 + - ``pad`` + - Pad number as reported by the media controller API. + * - __u32 + - ``code`` + - The media bus format code, as defined in + :ref:`v4l2-mbus-format`. + * - __u32 + - ``min_width`` + - Minimum frame width, in pixels. + * - __u32 + - ``max_width`` + - Maximum frame width, in pixels. + * - __u32 + - ``min_height`` + - Minimum frame height, in pixels. + * - __u32 + - ``max_height`` + - Maximum frame height, in pixels. + * - __u32 + - ``which`` + - Frame sizes to be enumerated, from enum + :ref:`v4l2_subdev_format_whence <v4l2-subdev-format-whence>`. + * - __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 + :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. |