Adding upstream version 5.10.209.upstream/5.10.209upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 162 insertions, 0 deletions

diff --git a/Documentation/userspace-api/media/v4l/vidioc-expbuf.rst b/Documentation/userspace-api/media/v4l/vidioc-expbuf.rst
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+.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
+.. c:namespace:: V4L
+
+.. _VIDIOC_EXPBUF:
+
+*******************
+ioctl VIDIOC_EXPBUF
+*******************
+
+Name
+====
+
+VIDIOC_EXPBUF - Export a buffer as a DMABUF file descriptor.
+
+Synopsis
+========
+
+.. c:macro:: VIDIOC_EXPBUF
+
+``int ioctl(int fd, VIDIOC_EXPBUF, struct v4l2_exportbuffer *argp)``
+
+Arguments
+=========
+
+``fd``
+    File descriptor returned by :c:func:`open()`.
+
+``argp``
+    Pointer to struct :c:type:`v4l2_exportbuffer`.
+
+Description
+===========
+
+This ioctl is an extension to the :ref:`memory mapping <mmap>` I/O
+method, therefore it is available only for ``V4L2_MEMORY_MMAP`` buffers.
+It can be used to export a buffer as a DMABUF file at any time after
+buffers have been allocated with the
+:ref:`VIDIOC_REQBUFS` ioctl.
+
+To export a buffer, applications fill struct
+:c:type:`v4l2_exportbuffer`. The ``type`` field is
+set to the same buffer type as was previously used with struct
+:c:type:`v4l2_requestbuffers` ``type``.
+Applications must also set 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. For the multi-planar API, applications set the ``plane`` field to
+the index of the plane to be exported. Valid planes range from zero to
+the maximal number of valid planes for the currently active format. For
+the single-planar API, applications must set ``plane`` to zero.
+Additional flags may be posted in the ``flags`` field. Refer to a manual
+for open() for details. Currently only O_CLOEXEC, O_RDONLY, O_WRONLY,
+and O_RDWR are supported. All other fields must be set to zero. In the
+case of multi-planar API, every plane is exported separately using
+multiple :ref:`VIDIOC_EXPBUF` calls.
+
+After calling :ref:`VIDIOC_EXPBUF` the ``fd`` field will be set by a
+driver. This is a DMABUF file descriptor. The application may pass it to
+other DMABUF-aware devices. Refer to :ref:`DMABUF importing <dmabuf>`
+for details about importing DMABUF files into V4L2 nodes. It is
+recommended to close a DMABUF file when it is no longer used to allow
+the associated memory to be reclaimed.
+
+Examples
+========
+
+.. code-block:: c
+
+    int buffer_export(int v4lfd, enum v4l2_buf_type bt, int index, int *dmafd)
+    {
+	struct v4l2_exportbuffer expbuf;
+
+	memset(&expbuf, 0, sizeof(expbuf));
+	expbuf.type = bt;
+	expbuf.index = index;
+	if (ioctl(v4lfd, VIDIOC_EXPBUF, &expbuf) == -1) {
+	    perror("VIDIOC_EXPBUF");
+	    return -1;
+	}
+
+	*dmafd = expbuf.fd;
+
+	return 0;
+    }
+
+.. code-block:: c
+
+    int buffer_export_mp(int v4lfd, enum v4l2_buf_type bt, int index,
+	int dmafd[], int n_planes)
+    {
+	int i;
+
+	for (i = 0; i < n_planes; ++i) {
+	    struct v4l2_exportbuffer expbuf;
+
+	    memset(&expbuf, 0, sizeof(expbuf));
+	    expbuf.type = bt;
+	    expbuf.index = index;
+	    expbuf.plane = i;
+	    if (ioctl(v4lfd, VIDIOC_EXPBUF, &expbuf) == -1) {
+		perror("VIDIOC_EXPBUF");
+		while (i)
+		    close(dmafd[--i]);
+		return -1;
+	    }
+	    dmafd[i] = expbuf.fd;
+	}
+
+	return 0;
+    }
+
+.. c:type:: v4l2_exportbuffer
+
+.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}|
+
+.. flat-table:: struct v4l2_exportbuffer
+    :header-rows:  0
+    :stub-columns: 0
+    :widths:       1 1 2
+
+    * - __u32
+      - ``type``
+      - Type of the buffer, same as struct
+	:c:type:`v4l2_format` ``type`` or struct
+	:c:type:`v4l2_requestbuffers` ``type``, set
+	by the application. See :c:type:`v4l2_buf_type`
+    * - __u32
+      - ``index``
+      - Number of the buffer, set by the application. This field is only
+	used for :ref:`memory mapping <mmap>` I/O and can range from
+	zero to the number of buffers allocated with the
+	:ref:`VIDIOC_REQBUFS` and/or
+	:ref:`VIDIOC_CREATE_BUFS` ioctls.
+    * - __u32
+      - ``plane``
+      - Index of the plane to be exported when using the multi-planar API.
+	Otherwise this value must be set to zero.
+    * - __u32
+      - ``flags``
+      - Flags for the newly created file, currently only ``O_CLOEXEC``,
+	``O_RDONLY``, ``O_WRONLY``, and ``O_RDWR`` are supported, refer to
+	the manual of open() for more details.
+    * - __s32
+      - ``fd``
+      - The DMABUF file descriptor associated with a buffer. Set by the
+	driver.
+    * - __u32
+      - ``reserved[11]``
+      - Reserved field for future use. Drivers and applications must set
+	the array to zero.
+
+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
+    A queue is not in MMAP mode or DMABUF exporting is not supported or
+    ``flags`` or ``type`` or ``index`` or ``plane`` fields are invalid.