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diff --git a/Documentation/media/uapi/v4l/io.rst b/Documentation/media/uapi/v4l/io.rst deleted file mode 100644 index 049a2530d3a2..000000000000 --- a/Documentation/media/uapi/v4l/io.rst +++ /dev/null @@ -1,58 +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 - -.. _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 :ref:`read() <func-read>` and -:ref:`write() <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` 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. - -:ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` and :ref:`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 |