Lines Matching +full:suspend +full:- +full:to +full:- +full:disk

1 .. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
16 with the memory type set to ``V4L2_MEMORY_USERPTR``.
20 can reside for example in virtual or shared memory. Only pointers to
21 data are exchanged, these pointers and meta-information are passed in
23 :c:type:`v4l2_plane` in the multi-planar API case). The
33 .. code-block:: c
41     if (ioctl (fd, VIDIOC_REQBUFS, &reqbuf) == -1) {
54 driver swaps memory pages within physical memory to create a continuous
55 area of memory. This happens transparently to the application in the
57 swapped out to disk they are brought back and finally locked in physical
66 Applications must take care not to free buffers without dequeuing.
68 Secondly the driver will not be notified when the memory is returned to
72 For capturing applications it is customary to enqueue a number of empty
73 buffers, to start capturing and enter the read loop. Here the
74 application waits until a filled buffer can be dequeued, and re-enqueues
79 Two methods exist to suspend execution of the application until one or
82 ``O_NONBLOCK`` flag was given to the :c:func:`open()` function,
85 <func-select>` or :c:func:`poll()` function are always
88 To start and stop capturing or output applications call the
97    application needs to synchronize with another event it should examine
109    Anyway, the process of swapping, locking or generating scatter-gather
112    a buffer will be soon enqueued again. On the other hand, to optimize
115    the pages of empty buffers in the incoming queue need not be saved to
116    disk. Output buffers must be saved on the incoming and outgoing queue
121    the same, and :c:func:`select()` is too important to be optional.