diff options
Diffstat (limited to 'Documentation/media/uapi/v4l/buffer.rst')
| -rw-r--r-- | Documentation/media/uapi/v4l/buffer.rst | 14 |
1 files changed, 10 insertions, 4 deletions
diff --git a/Documentation/media/uapi/v4l/buffer.rst b/Documentation/media/uapi/v4l/buffer.rst index 58a6d7d336e6..2e266d32470a 100644 --- a/Documentation/media/uapi/v4l/buffer.rst +++ b/Documentation/media/uapi/v4l/buffer.rst @@ -308,12 +308,18 @@ struct v4l2_buffer * - __u32 - ``request_fd`` - - - The file descriptor of the request to queue the buffer to. If specified - and flag ``V4L2_BUF_FLAG_REQUEST_FD`` is set, then the buffer will be - queued to that request. This is set by the user when calling - :ref:`ioctl VIDIOC_QBUF <VIDIOC_QBUF>` and ignored by other ioctls. + - The file descriptor of the request to queue the buffer to. If the flag + ``V4L2_BUF_FLAG_REQUEST_FD`` is set, then the buffer will be + queued to this request. If the flag is not set, then this field will + be ignored. + + The ``V4L2_BUF_FLAG_REQUEST_FD`` flag and this field are only used by + :ref:`ioctl VIDIOC_QBUF <VIDIOC_QBUF>` and ignored by other ioctls that + take a :c:type:`v4l2_buffer` as argument. + Applications should not set ``V4L2_BUF_FLAG_REQUEST_FD`` for any ioctls other than :ref:`VIDIOC_QBUF <VIDIOC_QBUF>`. + If the device does not support requests, then ``EACCES`` will be returned. If requests are supported but an invalid request file descriptor is given, then ``EINVAL`` will be returned. |