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Diffstat (limited to 'Documentation/userspace-api/media/v4l/io.rst')
| -rw-r--r-- | Documentation/userspace-api/media/v4l/io.rst | 10 |
1 files changed, 4 insertions, 6 deletions
diff --git a/Documentation/userspace-api/media/v4l/io.rst b/Documentation/userspace-api/media/v4l/io.rst index 9dc36b41dbf6..4b1964df9d73 100644 --- a/Documentation/userspace-api/media/v4l/io.rst +++ b/Documentation/userspace-api/media/v4l/io.rst @@ -1,4 +1,5 @@ .. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later +.. c:namespace:: V4L .. _io: @@ -9,15 +10,14 @@ 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 +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` ioctl. The asynchronous I/O -method is not defined yet. +:ref:`VIDIOC_REQBUFS` ioctl. Video overlay can be considered another I/O method, although the application does not directly receive the image data. It is selected by @@ -38,7 +38,6 @@ closing and reopening the device. The following sections describe the various I/O methods in more detail. - .. toctree:: :maxdepth: 1 @@ -46,6 +45,5 @@ The following sections describe the various I/O methods in more detail. mmap userp dmabuf - async buffer field-order |