Lines Matching +full:capture +full:- +full:subsystem

1 .. SPDX-License-Identifier: GPL-2.0 OR GFDL-1.1-no-invariants-or-later
4 .. _media-request-api:
12 the same pipeline to reconfigure and collaborate closely on a per-frame basis.
14 to specific frames (aka 'per-frame controls') in order to be used efficiently.
16 While the initial use-case was V4L2, it can be extended to other subsystems
20 it is, it is terribly inefficient: user-space would have to flush all activity
28 specific buffers. This allows user-space to schedule several tasks ("requests")
34 -------------
37 subsystem-specific APIs to support request usage. At the Media Controller
41 stored in requests are accessed through subsystem-specific APIs extended for
46 ------------------
48 User-space allocates requests using :ref:`MEDIA_IOC_REQUEST_ALLOC`
53 -------------------
63 ------------------
71    For :ref:`memory-to-memory devices <mem2mem>` you can use requests only for
72    output buffers, not for capture buffers. Attempting to add a capture buffer
85    :ref:`closed <func-close>`. Attempts to directly queue a buffer when earlier
97 User-space can :c:func:`poll()` a request file descriptor in
101 Note that user-space does not need to wait for the request to complete to
106 executed. User-space can query that state by calling
113 .. _media-request-life-time:
116 -------------------------
130 --------------------------
132 For use-cases such as :ref:`codecs <mem2mem>`, the request API can be used
134 be applied by the driver for the OUTPUT buffer, allowing user-space
136 ability to capture the state of controls when the request completes to read back
139 Put into code, after obtaining a request, user-space can assign controls and one
142 .. code-block:: c
162 Note that it is not allowed to use the Request API for CAPTURE buffers
163 since there are no per-frame settings to report there.
167 .. code-block:: c
172 User-space can then either wait for the request to complete by calling poll() on
173 its file descriptor, or start dequeuing CAPTURE buffers. Most likely, it will
174 want to get CAPTURE buffers as soon as possible and this can be done using a
177 .. code-block:: c
187 there will be one CAPTURE buffer, but this does not have to be the case.
193 query values as soon as the capture buffer is produced.
195 .. code-block:: c
198 	poll(&pfd, 1, -1);
208 .. code-block:: c
215 .. code-block:: c
219 Example for a Simple Capture Device
220 -----------------------------------
222 With a simple capture device, requests can be used to specify controls to apply
223 for a given CAPTURE buffer.
225 .. code-block:: c
247 .. code-block:: c
252 User-space can then dequeue buffers, wait for the request completion, query