diff options
Diffstat (limited to 'Documentation/userspace-api/media/v4l/vidioc-qbuf.rst')
| -rw-r--r-- | Documentation/userspace-api/media/v4l/vidioc-qbuf.rst | 21 |
1 files changed, 10 insertions, 11 deletions
diff --git a/Documentation/userspace-api/media/v4l/vidioc-qbuf.rst b/Documentation/userspace-api/media/v4l/vidioc-qbuf.rst index cd920d0b6adf..e4b3d9beb9ab 100644 --- a/Documentation/userspace-api/media/v4l/vidioc-qbuf.rst +++ b/Documentation/userspace-api/media/v4l/vidioc-qbuf.rst @@ -1,4 +1,5 @@ .. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later +.. c:namespace:: V4L .. _VIDIOC_QBUF: @@ -11,27 +12,26 @@ Name VIDIOC_QBUF - VIDIOC_DQBUF - Exchange a buffer with the driver - Synopsis ======== -.. c:function:: int ioctl( int fd, VIDIOC_QBUF, struct v4l2_buffer *argp ) - :name: VIDIOC_QBUF +.. c:macro:: VIDIOC_QBUF + +``int ioctl(int fd, VIDIOC_QBUF, struct v4l2_buffer *argp)`` -.. c:function:: int ioctl( int fd, VIDIOC_DQBUF, struct v4l2_buffer *argp ) - :name: VIDIOC_DQBUF +.. c:macro:: VIDIOC_DQBUF +``int ioctl(int fd, VIDIOC_DQBUF, struct v4l2_buffer *argp)`` Arguments ========= ``fd`` - File descriptor returned by :ref:`open() <func-open>`. + File descriptor returned by :c:func:`open()`. ``argp`` Pointer to struct :c:type:`v4l2_buffer`. - Description =========== @@ -125,7 +125,7 @@ Applications call the ``VIDIOC_DQBUF`` ioctl to dequeue a filled queue. They just set the ``type``, ``memory`` and ``reserved`` fields of a struct :c:type:`v4l2_buffer` as above, when ``VIDIOC_DQBUF`` is called with a pointer to this structure the driver -fills the remaining fields or returns an error code. The driver may also +fills all remaining fields or returns an error code. The driver may also set ``V4L2_BUF_FLAG_ERROR`` in the ``flags`` field. It indicates a non-critical (recoverable) streaming error. In such case the application may continue as normal, but should be aware that data in the dequeued @@ -142,13 +142,12 @@ API is used the ``m.fd`` fields of the passed array of struct By default ``VIDIOC_DQBUF`` blocks when no buffer is in the outgoing queue. When the ``O_NONBLOCK`` flag was given to the -:ref:`open() <func-open>` function, ``VIDIOC_DQBUF`` returns +:c:func:`open()` function, ``VIDIOC_DQBUF`` returns immediately with an ``EAGAIN`` error code when no buffer is available. The struct :c:type:`v4l2_buffer` structure is specified in :ref:`buffer`. - Return Value ============ @@ -164,7 +163,7 @@ EINVAL The buffer ``type`` is not supported, or the ``index`` is out of bounds, or no buffers have been allocated yet, or the ``userptr`` or ``length`` are invalid, or the ``V4L2_BUF_FLAG_REQUEST_FD`` flag was - set but the the given ``request_fd`` was invalid, or ``m.fd`` was + set but the given ``request_fd`` was invalid, or ``m.fd`` was an invalid DMABUF file descriptor. EIO |