doc-rst: linux_tv DocBook to reST migration (docs-next)
This is the restructuredText (reST) migration of the ``media``
DocBook-XML set from the linux_tv project.
Signed-off-by: Markus Heiser <markus.heiser@darmarIT.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
diff --git a/Documentation/linux_tv/media/v4l/io.rst b/Documentation/linux_tv/media/v4l/io.rst
new file mode 100644
index 0000000..a7ca0d5
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+++ b/Documentation/linux_tv/media/v4l/io.rst
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+.. -*- coding: utf-8; mode: rst -*-
+
+.. _io:
+
+############
+Input/Output
+############
+The V4L2 API defines several different methods to read from or write to
+a device. All drivers exchanging data with applications must support at
+least one of them.
+
+The classic I/O method using the :c:func:`read()` and
+:c:func:`write()` function is automatically selected after opening a
+V4L2 device. When the driver does not support this method attempts to
+read or write will fail at any time.
+
+Other methods must be negotiated. To select the streaming I/O method
+with memory mapped or user buffers applications call the
+:ref:`VIDIOC_REQBUFS <vidioc-reqbufs>` ioctl. The asynchronous I/O
+method is not defined yet.
+
+Video overlay can be considered another I/O method, although the
+application does not directly receive the image data. It is selected by
+initiating video overlay with the :ref:`VIDIOC_S_FMT <vidioc-g-fmt>`
+ioctl. For more information see :ref:`overlay`.
+
+Generally exactly one I/O method, including overlay, is associated with
+each file descriptor. The only exceptions are applications not
+exchanging data with a driver ("panel applications", see :ref:`open`)
+and drivers permitting simultaneous video capturing and overlay using
+the same file descriptor, for compatibility with V4L and earlier
+versions of V4L2.
+
+``VIDIOC_S_FMT`` and ``VIDIOC_REQBUFS`` would permit this to some
+degree, but for simplicity drivers need not support switching the I/O
+method (after first switching away from read/write) other than by
+closing and reopening the device.
+
+The following sections describe the various I/O methods in more detail.
+
+
+.. toctree::
+ :maxdepth: 1
+
+ rw
+ mmap
+ userp
+ dmabuf
+ async
+ buffer
+ field-order
+
+
+
+
+.. ------------------------------------------------------------------------------
+.. This file was automatically converted from DocBook-XML with the dbxml
+.. library (https://github.com/return42/sphkerneldoc). The origin XML comes
+.. from the linux kernel, refer to:
+..
+.. * https://github.com/torvalds/linux/tree/master/Documentation/DocBook
+.. ------------------------------------------------------------------------------