diff options
Diffstat (limited to 'Documentation/media/uapi/v4l/vidioc-querybuf.rst')
| -rw-r--r-- | Documentation/media/uapi/v4l/vidioc-querybuf.rst | 87 |
1 files changed, 0 insertions, 87 deletions
diff --git a/Documentation/media/uapi/v4l/vidioc-querybuf.rst b/Documentation/media/uapi/v4l/vidioc-querybuf.rst deleted file mode 100644 index 7da60b24e8b6..000000000000 --- a/Documentation/media/uapi/v4l/vidioc-querybuf.rst +++ /dev/null @@ -1,87 +0,0 @@ -.. 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/media/uapi/fdl-appendix.rst. -.. -.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections - -.. _VIDIOC_QUERYBUF: - -********************* -ioctl VIDIOC_QUERYBUF -********************* - -Name -==== - -VIDIOC_QUERYBUF - Query the status of a buffer - - -Synopsis -======== - -.. c:function:: int ioctl( int fd, VIDIOC_QUERYBUF, struct v4l2_buffer *argp ) - :name: VIDIOC_QUERYBUF - - -Arguments -========= - -``fd`` - File descriptor returned by :ref:`open() <func-open>`. - -``argp`` - Pointer to struct :c:type:`v4l2_buffer`. - - -Description -=========== - -This ioctl is part of the :ref:`streaming <mmap>` I/O method. It can -be used to query the status of a buffer at any time after buffers have -been allocated with the :ref:`VIDIOC_REQBUFS` ioctl. - -Applications set the ``type`` field of a struct -:c:type:`v4l2_buffer` to the same buffer type as was -previously used with struct :c:type:`v4l2_format` ``type`` -and struct :c:type:`v4l2_requestbuffers` ``type``, -and the ``index`` field. Valid index numbers range from zero to the -number of buffers allocated with -:ref:`VIDIOC_REQBUFS` (struct -:c:type:`v4l2_requestbuffers` ``count``) minus -one. The ``reserved`` and ``reserved2`` fields must be set to 0. When -using the :ref:`multi-planar API <planar-apis>`, the ``m.planes`` -field must contain a userspace pointer to an array of struct -:c:type:`v4l2_plane` and the ``length`` field has to be set -to the number of elements in that array. After calling -:ref:`VIDIOC_QUERYBUF` with a pointer to this structure drivers return an -error code or fill the rest of the structure. - -In the ``flags`` field the ``V4L2_BUF_FLAG_MAPPED``, -``V4L2_BUF_FLAG_PREPARED``, ``V4L2_BUF_FLAG_QUEUED`` and -``V4L2_BUF_FLAG_DONE`` flags will be valid. The ``memory`` field will be -set to the current I/O method. For the single-planar API, the -``m.offset`` contains the offset of the buffer from the start of the -device memory, the ``length`` field its size. For the multi-planar API, -fields ``m.mem_offset`` and ``length`` in the ``m.planes`` array -elements will be used instead and the ``length`` field of struct -:c:type:`v4l2_buffer` is set to the number of filled-in -array elements. The driver may or may not set the remaining fields and -flags, they are meaningless in this context. - -The struct :c:type:`v4l2_buffer` structure is specified in -:ref:`buffer`. - - -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 buffer ``type`` is not supported, or the ``index`` is out of - bounds. |