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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 | 56 |
1 files changed, 36 insertions, 20 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 index c25a9896df0e..65f0cfeca973 100644 --- a/Documentation/userspace-api/media/v4l/vidioc-subdev-enum-frame-size.rst +++ b/Documentation/userspace-api/media/v4l/vidioc-subdev-enum-frame-size.rst @@ -31,18 +31,30 @@ Arguments 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 +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. -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. +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 @@ -72,32 +84,37 @@ information about try formats. * - __u32 - ``index`` - - Number of the format in the enumeration, set by the application. + - 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`. + :ref:`v4l2-mbus-format`. Filled in by the application. * - __u32 - ``min_width`` - - Minimum frame width, in pixels. + - Minimum frame width, in pixels. Filled in by the driver. * - __u32 - ``max_width`` - - Maximum frame width, in pixels. + - Maximum frame width, in pixels. Filled in by the driver. * - __u32 - ``min_height`` - - Minimum frame height, in pixels. + - Minimum frame height, in pixels. Filled in by the driver. * - __u32 - ``max_height`` - - Maximum frame height, in pixels. + - 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 - - ``reserved``\ [8] + - ``stream`` + - Stream identifier. + * - __u32 + - ``reserved``\ [7] - Reserved for future extensions. Applications and drivers must set the array to zero. @@ -109,7 +126,6 @@ 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. + The struct :c:type:`v4l2_subdev_frame_size_enum` ``pad`` references a + non-existing pad, the ``which`` field has an unsupported value, the ``code`` + is invalid for the given pad, or the ``index`` field is out of bounds. |