Lines Matching +full:multi +full:- +full:sensor
1 .. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
6 Sub-device Interface
13 components as software blocks called sub-devices.
15 V4L2 sub-devices are usually kernel-only objects. If the V4L2 driver
17 media entities. Applications will be able to enumerate the sub-devices
21 In addition to make sub-devices discoverable, drivers can also choose to
23 sub-device driver and the V4L2 device driver support this, sub-devices
26 - query, read and write sub-devices controls
28 - subscribe and unsubscribe to events and retrieve them
30 - negotiate image formats on individual pads
32 Sub-device character device nodes, conventionally named
33 ``/dev/v4l-subdev*``, use major number 81.
35 Drivers may opt to limit the sub-device character devices to only expose
36 operations that do not modify the device state. In such a case the sub-devices
37 are referred to as ``read-only`` in the rest of this documentation, and the
44 Most V4L2 controls are implemented by sub-device hardware. Drivers
46 Applications can control all sub-devices through a single interface.
55 Applications can access those hidden controls through the sub-device
59 sub-device.
68 V4L2 sub-devices can notify applications of events as described in
71 the sub-device. Depending on the driver, those events might also be
75 .. _pad-level-formats:
77 Pad-level Formats
82 Pad-level formats are only applicable to very complex devices that
83 need to expose low-level format configuration to user space. Generic
101 :ref:`pipeline-scaling`, where image scaling can be performed on both
102 the video sensor and the host image processing hardware.
105 .. _pipeline-scaling:
107 .. kernel-figure:: pipeline.dot
117 The sensor scaler is usually of less quality than the host scaler, but
118 scaling on the sensor is required to achieve higher frame rates.
123 Drivers that implement the :ref:`media API <media-controller-intro>`
124 can expose pad-level image format configuration to applications. When
128 negotiate formats on a per-pad basis.
136 Pad-level image format configuration support can be tested by calling
138 0. If the driver returns an ``EINVAL`` error code pad-level format
139 configuration is not supported by the sub-device.
143 ------------------
162 the sub-device file handles. A
164 the last try format set *on the same sub-device file handle*. Several
165 applications querying the same sub-device at the same time will thus not
179 to an :ref:`VIDIOC_SUBDEV_S_FMT <VIDIOC_SUBDEV_G_FMT>` call as-is
183 Drivers automatically propagate formats inside sub-devices. When a try
185 the same sub-device can be modified by the driver. Drivers are free to
189 - Formats should be propagated from sink pads to source pads. Modifying
193 - Sub-devices that scale frames using variable scaling factors should
199 propagating them from one sub-device file handle to another.
205 :ref:`sample-pipeline-config` shows a sample configuration sequence
206 for the pipeline described in :ref:`pipeline-scaling` (table columns
218 .. _sample-pipeline-config:
220 .. flat-table:: Sample Pipeline Configuration
221 :header-rows: 1
222 :stub-columns: 0
225 * -
226 - Sensor/0
229 - Frontend/0
232 - Frontend/1
235 - Scaler/0
238 - Scaler/0
241 - Scaler/1
244 * - Initial state
245 - 2048x1536
248 - (default)
249 - (default)
250 - (default)
251 - (default)
252 - (default)
253 * - Configure frontend sink format
254 - 2048x1536
257 - *2048x1536*
260 - *2046x1534*
263 - (default)
264 - (default)
265 - (default)
266 * - Configure scaler sink format
267 - 2048x1536
270 - 2048x1536
273 - 2046x1534
276 - *2046x1534*
279 - *0,0/2046x1534*
280 - *2046x1534*
283 * - Configure scaler sink compose selection
284 - 2048x1536
287 - 2048x1536
290 - 2046x1534
293 - 2046x1534
296 - *0,0/1280x960*
297 - *1280x960*
305 1. Initial state. The sensor source pad format is set to its native 3MP
332 be applied as-is by the driver without being modified.
335 .. _v4l2-subdev-selections:
338 ---------------------------------------------
340 Many sub-devices support cropping frames on their input or output pads
342 interest in an image, typically on an image sensor or a video decoder.
352 selection targets :ref:`v4l2-selections-common`.
355 The pad format represents the image size as received by the sub-device
357 represents the sub-image that will be transmitted further inside the
358 sub-device for processing.
382 the image size either up or down. :ref:`v4l2-selection-flags`
386 --------------------------
402 as the BOUNDS rectangle, however. This may be because e.g. a sensor's
403 pixel array is not rectangular but cross-shaped or round. The maximum
408 ---------------------------------------------
421 rectangle, which refers to the sink compose bounds rectangle --- if it
452 .. _subdev-image-processing-crop:
454 .. kernel-figure:: subdev-image-processing-crop.svg
455 :alt: subdev-image-processing-crop.svg
462 pad. Now the actual crop rectangle can be set on the sink pad --- the
469 .. _subdev-image-processing-scaling-multi-source:
471 .. kernel-figure:: subdev-image-processing-scaling-multi-source.svg
472 :alt: subdev-image-processing-scaling-multi-source.svg
485 .. _subdev-image-processing-full:
487 .. kernel-figure:: subdev-image-processing-full.svg
488 :alt: subdev-image-processing-full.svg
503 subdev-formats