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diff --git a/Documentation/media/uapi/v4l/vidioc-enum-framesizes.rst b/Documentation/media/uapi/v4l/vidioc-enum-framesizes.rst new file mode 100644 index 000000000000..d3b2e97df6c9 --- /dev/null +++ b/Documentation/media/uapi/v4l/vidioc-enum-framesizes.rst @@ -0,0 +1,291 @@ +.. -*- coding: utf-8; mode: rst -*- + +.. _VIDIOC_ENUM_FRAMESIZES: + +**************************** +ioctl VIDIOC_ENUM_FRAMESIZES +**************************** + +Name +==== + +VIDIOC_ENUM_FRAMESIZES - Enumerate frame sizes + + +Synopsis +======== + +.. cpp:function:: int ioctl( int fd, int request, struct v4l2_frmsizeenum *argp ) + + +Arguments +========= + +``fd`` + File descriptor returned by :ref:`open() <func-open>`. + +``request`` + VIDIOC_ENUM_FRAMESIZES + +``argp`` + Pointer to a struct :ref:`v4l2_frmsizeenum <v4l2-frmsizeenum>` + that contains an index and pixel format and receives a frame width + and height. + + +Description +=========== + +This ioctl allows applications to enumerate all frame sizes (i. e. width +and height in pixels) that the device supports for the given pixel +format. + +The supported pixel formats can be obtained by using the +:ref:`VIDIOC_ENUM_FMT` function. + +The return value and the content of the ``v4l2_frmsizeenum.type`` field +depend on the type of frame sizes the device supports. Here are the +semantics of the function for the different cases: + +- **Discrete:** The function returns success if the given index value + (zero-based) is valid. The application should increase the index by + one for each call until ``EINVAL`` is returned. The + ``v4l2_frmsizeenum.type`` field is set to + ``V4L2_FRMSIZE_TYPE_DISCRETE`` by the driver. Of the union only the + ``discrete`` member is valid. + +- **Step-wise:** The function returns success if the given index value + is zero and ``EINVAL`` for any other index value. The + ``v4l2_frmsizeenum.type`` field is set to + ``V4L2_FRMSIZE_TYPE_STEPWISE`` by the driver. Of the union only the + ``stepwise`` member is valid. + +- **Continuous:** This is a special case of the step-wise type above. + The function returns success if the given index value is zero and + ``EINVAL`` for any other index value. The ``v4l2_frmsizeenum.type`` + field is set to ``V4L2_FRMSIZE_TYPE_CONTINUOUS`` by the driver. Of + the union only the ``stepwise`` member is valid and the + ``step_width`` and ``step_height`` values are set to 1. + +When the application calls the function with index zero, it must check +the ``type`` field to determine the type of frame size enumeration the +device supports. Only for the ``V4L2_FRMSIZE_TYPE_DISCRETE`` type does +it make sense to increase the index value to receive more frame sizes. + +Note that the order in which the frame sizes are returned has no special +meaning. In particular does it not say anything about potential default +format sizes. + +Applications can assume that the enumeration data does not change +without any interaction from the application itself. This means that the +enumeration data is consistent if the application does not perform any +other ioctl calls while it runs the frame size enumeration. + + +Structs +======= + +In the structs below, *IN* denotes a value that has to be filled in by +the application, *OUT* denotes values that the driver fills in. The +application should zero out all members except for the *IN* fields. + + +.. _v4l2-frmsize-discrete: + +.. flat-table:: struct v4l2_frmsize_discrete + :header-rows: 0 + :stub-columns: 0 + :widths: 1 1 2 + + + - .. row 1 + + - __u32 + + - ``width`` + + - Width of the frame [pixel]. + + - .. row 2 + + - __u32 + + - ``height`` + + - Height of the frame [pixel]. + + + +.. _v4l2-frmsize-stepwise: + +.. flat-table:: struct v4l2_frmsize_stepwise + :header-rows: 0 + :stub-columns: 0 + :widths: 1 1 2 + + + - .. row 1 + + - __u32 + + - ``min_width`` + + - Minimum frame width [pixel]. + + - .. row 2 + + - __u32 + + - ``max_width`` + + - Maximum frame width [pixel]. + + - .. row 3 + + - __u32 + + - ``step_width`` + + - Frame width step size [pixel]. + + - .. row 4 + + - __u32 + + - ``min_height`` + + - Minimum frame height [pixel]. + + - .. row 5 + + - __u32 + + - ``max_height`` + + - Maximum frame height [pixel]. + + - .. row 6 + + - __u32 + + - ``step_height`` + + - Frame height step size [pixel]. + + + +.. _v4l2-frmsizeenum: + +.. flat-table:: struct v4l2_frmsizeenum + :header-rows: 0 + :stub-columns: 0 + + + - .. row 1 + + - __u32 + + - ``index`` + + - + - IN: Index of the given frame size in the enumeration. + + - .. row 2 + + - __u32 + + - ``pixel_format`` + + - + - IN: Pixel format for which the frame sizes are enumerated. + + - .. row 3 + + - __u32 + + - ``type`` + + - + - OUT: Frame size type the device supports. + + - .. row 4 + + - union + + - + - + - OUT: Frame size with the given index. + + - .. row 5 + + - + - struct :ref:`v4l2_frmsize_discrete <v4l2-frmsize-discrete>` + + - ``discrete`` + + - + + - .. row 6 + + - + - struct :ref:`v4l2_frmsize_stepwise <v4l2-frmsize-stepwise>` + + - ``stepwise`` + + - + + - .. row 7 + + - __u32 + + - ``reserved[2]`` + + - + - Reserved space for future use. Must be zeroed by drivers and + applications. + + + +Enums +===== + + +.. _v4l2-frmsizetypes: + +.. flat-table:: enum v4l2_frmsizetypes + :header-rows: 0 + :stub-columns: 0 + :widths: 3 1 4 + + + - .. row 1 + + - ``V4L2_FRMSIZE_TYPE_DISCRETE`` + + - 1 + + - Discrete frame size. + + - .. row 2 + + - ``V4L2_FRMSIZE_TYPE_CONTINUOUS`` + + - 2 + + - Continuous frame size. + + - .. row 3 + + - ``V4L2_FRMSIZE_TYPE_STEPWISE`` + + - 3 + + - Step-wise defined frame size. + + +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. |