media: docs: move uAPI book to userspace-api/media

[sfrench/cifs-2.6.git] / Documentation / media / uapi / v4l / func-write.rst

diff --git a/Documentation/media/uapi/v4l/func-write.rst b/Documentation/media/uapi/v4l/func-write.rst
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-.. 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
-
-.. _func-write:
-
-************
-V4L2 write()
-************
-
-Name
-====
-
-v4l2-write - Write to a V4L2 device
-
-
-Synopsis
-========
-
-.. code-block:: c
-
-    #include <unistd.h>
-
-
-.. c:function:: ssize_t write( int fd, void *buf, size_t count )
-    :name: v4l2-write
-
-Arguments
-=========
-
-``fd``
-    File descriptor returned by :ref:`open() <func-open>`.
-
-``buf``
-     Buffer with data to be written
-
-``count``
-    Number of bytes at the buffer
-
-Description
-===========
-
-:ref:`write() <func-write>` writes up to ``count`` bytes to the device
-referenced by the file descriptor ``fd`` from the buffer starting at
-``buf``. When the hardware outputs are not active yet, this function
-enables them. When ``count`` is zero, :ref:`write() <func-write>` returns 0
-without any other effect.
-
-When the application does not provide more data in time, the previous
-video frame, raw VBI image, sliced VPS or WSS data is displayed again.
-Sliced Teletext or Closed Caption data is not repeated, the driver
-inserts a blank line instead.
-
-
-Return Value
-============
-
-On success, the number of bytes written are returned. Zero indicates
-nothing was written. On error, -1 is returned, and the ``errno``
-variable is set appropriately. In this case the next write will start at
-the beginning of a new frame. Possible error codes are:
-
-EAGAIN
-    Non-blocking I/O has been selected using the
-    :ref:`O_NONBLOCK <func-open>` flag and no buffer space was
-    available to write the data immediately.
-
-EBADF
-    ``fd`` is not a valid file descriptor or is not open for writing.
-
-EBUSY
-    The driver does not support multiple write streams and the device is
-    already in use.
-
-EFAULT
-    ``buf`` references an inaccessible memory area.
-
-EINTR
-    The call was interrupted by a signal before any data was written.
-
-EIO
-    I/O error. This indicates some hardware problem.
-
-EINVAL
-    The :ref:`write() <func-write>` function is not supported by this driver,
-    not on this device, or generally not on this type of device.