summaryrefslogtreecommitdiff
path: root/src/libcamera/pipeline_handler.cpp
blob: 675405330f4532b6aee7936347f91fcff9a31c9a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
 * Copyright (C) 2018, Google Inc.
 *
 * pipeline_handler.cpp - Pipeline handler infrastructure
 */

#include "libcamera/internal/pipeline_handler.h"

#include <chrono>
#include <sys/sysmacros.h>

#include <libcamera/base/log.h>
#include <libcamera/base/mutex.h>
#include <libcamera/base/utils.h>

#include <libcamera/camera.h>
#include <libcamera/camera_manager.h>
#include <libcamera/framebuffer.h>

#include "libcamera/internal/camera.h"
#include "libcamera/internal/device_enumerator.h"
#include "libcamera/internal/framebuffer.h"
#include "libcamera/internal/media_device.h"
#include "libcamera/internal/request.h"
#include "libcamera/internal/tracepoints.h"

/**
 * \file pipeline_handler.h
 * \brief Create pipelines and cameras from a set of media devices
 *
 * Each pipeline supported by libcamera needs to be backed by a pipeline
 * handler implementation that operate on a set of media devices. The pipeline
 * handler is responsible for matching the media devices it requires with the
 * devices present in the system, and once all those devices can be acquired,
 * create corresponding Camera instances.
 *
 * Every subclass of PipelineHandler shall be registered with libcamera using
 * the REGISTER_PIPELINE_HANDLER() macro.
 */

using namespace std::chrono_literals;

namespace libcamera {

LOG_DEFINE_CATEGORY(Pipeline)

/**
 * \class PipelineHandler
 * \brief Create and manage cameras based on a set of media devices
 *
 * The PipelineHandler matches the media devices provided by a DeviceEnumerator
 * with the pipelines it supports and creates corresponding Camera devices.
 *
 * Pipeline handler instances are reference-counted through std::shared_ptr<>.
 * They implement std::enable_shared_from_this<> in order to create new
 * std::shared_ptr<> in code paths originating from member functions of the
 * PipelineHandler class where only the 'this' pointer is available.
 */

/**
 * \brief Construct a PipelineHandler instance
 * \param[in] manager The camera manager
 *
 * In order to honour the std::enable_shared_from_this<> contract,
 * PipelineHandler instances shall never be constructed manually, but always
 * through the PipelineHandlerFactory::create() function implemented by the
 * respective factories.
 */
PipelineHandler::PipelineHandler(CameraManager *manager)
	: manager_(manager), lockOwner_(false)
{
}

PipelineHandler::~PipelineHandler()
{
	for (std::shared_ptr<MediaDevice> media : mediaDevices_)
		media->release();
}

/**
 * \fn PipelineHandler::match(DeviceEnumerator *enumerator)
 * \brief Match media devices and create camera instances
 * \param[in] enumerator The enumerator providing all media devices found in the
 * system
 *
 * This function is the main entry point of the pipeline handler. It is called
 * by the camera manager with the \a enumerator passed as an argument. It shall
 * acquire from the \a enumerator all the media devices it needs for a single
 * pipeline, create one or multiple Camera instances and register them with the
 * camera manager.
 *
 * If all media devices needed by the pipeline handler are found, they must all
 * be acquired by a call to MediaDevice::acquire(). This function shall then
 * create the corresponding Camera instances, store them internally, and return
 * true. Otherwise it shall not acquire any media device (or shall release all
 * the media devices is has acquired by calling MediaDevice::release()) and
 * return false.
 *
 * If multiple instances of a pipeline are available in the system, the
 * PipelineHandler class will be instantiated once per instance, and its match()
 * function called for every instance. Each call shall acquire media devices for
 * one pipeline instance, until all compatible media devices are exhausted.
 *
 * If this function returns true, a new instance of the pipeline handler will
 * be created and its match() function called.
 *
 * \context This function is called from the CameraManager thread.
 *
 * \return true if media devices have been acquired and camera instances
 * created, or false otherwise
 */

/**
 * \brief Search and acquire a MediaDevice matching a device pattern
 * \param[in] enumerator Enumerator containing all media devices in the system
 * \param[in] dm Device match pattern
 *
 * Search the device \a enumerator for an available media device matching the
 * device match pattern \a dm. Matching media device that have previously been
 * acquired by MediaDevice::acquire() are not considered. If a match is found,
 * the media device is acquired and returned. The caller shall not release the
 * device explicitly, it will be automatically released when the pipeline
 * handler is destroyed.
 *
 * \context This function shall be called from the CameraManager thread.
 *
 * \return A pointer to the matching MediaDevice, or nullptr if no match is found
 */
MediaDevice *PipelineHandler::acquireMediaDevice(DeviceEnumerator *enumerator,
						 const DeviceMatch &dm)
{
	std::shared_ptr<MediaDevice> media = enumerator->search(dm);
	if (!media)
		return nullptr;

	if (!media->acquire())
		return nullptr;

	mediaDevices_.push_back(media);

	return media.get();
}

/**
 * \brief Lock all media devices acquired by the pipeline
 *
 * This function shall not be called from pipeline handler implementation, as
 * the Camera class handles locking directly.
 *
 * \context This function is \threadsafe.
 *
 * \return True if the devices could be locked, false otherwise
 * \sa unlock()
 * \sa MediaDevice::lock()
 */
bool PipelineHandler::lock()
{
	MutexLocker locker(lock_);

	/* Do not allow nested locking in the same libcamera instance. */
	if (lockOwner_)
		return false;

	for (std::shared_ptr<MediaDevice> &media : mediaDevices_) {
		if (!media->lock()) {
			unlock();
			return false;
		}
	}

	lockOwner_ = true;

	return true;
}

/**
 * \brief Unlock all media devices acquired by the pipeline
 *
 * This function shall not be called from pipeline handler implementation, as
 * the Camera class handles locking directly.
 *
 * \context This function is \threadsafe.
 *
 * \sa lock()
 */
void PipelineHandler::unlock()
{
	MutexLocker locker(lock_);

	if (!lockOwner_)
		return;

	for (std::shared_ptr<MediaDevice> &media : mediaDevices_)
		media->unlock();

	lockOwner_ = false;
}

/**
 * \fn PipelineHandler::generateConfiguration()
 * \brief Generate a camera configuration for a specified camera
 * \param[in] camera The camera to generate a default configuration for
 * \param[in] roles A list of stream roles
 *
 * Generate a default configuration for the \a camera for a specified list of
 * stream roles. The caller shall populate the \a roles with the use-cases it
 * wishes to fetch the default configuration for. The returned configuration
 * can then be examined by the caller to learn about the selected streams and
 * their default parameters.
 *
 * The intended companion to this is \a configure() which can be used to change
 * the group of streams parameters.
 *
 * \context This function may be called from any thread and shall be
 * \threadsafe. It shall not modify the state of the \a camera in the pipeline
 * handler.
 *
 * \return A valid CameraConfiguration if the requested roles can be satisfied,
 * or a null pointer otherwise. The ownership of the returned configuration is
 * passed to the caller.
 */

/**
 * \fn PipelineHandler::configure()
 * \brief Configure a group of streams for capture
 * \param[in] camera The camera to configure
 * \param[in] config The camera configurations to setup
 *
 * Configure the specified group of streams for \a camera according to the
 * configuration specified in \a config. The intended caller of this interface
 * is the Camera class which will receive configuration to apply from the
 * application.
 *
 * The configuration is guaranteed to have been validated with
 * CameraConfiguration::validate(). The pipeline handler implementation shall
 * not perform further validation and may rely on any custom field stored in its
 * custom CameraConfiguration derived class.
 *
 * When configuring the camera the pipeline handler shall associate a Stream
 * instance to each StreamConfiguration entry in the CameraConfiguration using
 * the StreamConfiguration::setStream() function.
 *
 * \context This function is called from the CameraManager thread.
 *
 * \return 0 on success or a negative error code otherwise
 */

/**
 * \fn PipelineHandler::exportFrameBuffers()
 * \brief Allocate and export buffers for \a stream
 * \param[in] camera The camera
 * \param[in] stream The stream to allocate buffers for
 * \param[out] buffers Array of buffers successfully allocated
 *
 * This function allocates buffers for the \a stream from the devices associated
 * with the stream in the corresponding pipeline handler. Those buffers shall be
 * suitable to be added to a Request for the stream, and shall be mappable to
 * the CPU through their associated dmabufs with mmap().
 *
 * The function may only be called after the Camera has been configured and
 * before it gets started, or after it gets stopped. It shall be called only for
 * streams that are part of the active camera configuration.
 *
 * The only intended caller is Camera::exportFrameBuffers().
 *
 * \context This function is called from the CameraManager thread.
 *
 * \return The number of allocated buffers on success or a negative error code
 * otherwise
 */

/**
 * \fn PipelineHandler::start()
 * \brief Start capturing from a group of streams
 * \param[in] camera The camera to start
 * \param[in] controls Controls to be applied before starting the Camera
 *
 * Start the group of streams that have been configured for capture by
 * \a configure(). The intended caller of this function is the Camera class
 * which will in turn be called from the application to indicate that it has
 * configured the streams and is ready to capture.
 *
 * \context This function is called from the CameraManager thread.
 *
 * \return 0 on success or a negative error code otherwise
 */

/**
 * \brief Stop capturing from all running streams and cancel pending requests
 * \param[in] camera The camera to stop
 *
 * This function stops capturing and processing requests immediately. All
 * pending requests are cancelled and complete immediately in an error state.
 *
 * \context This function is called from the CameraManager thread.
 */
void PipelineHandler::stop(Camera *camera)
{
	/* Stop the pipeline handler and let the queued requests complete. */
	stopDevice(camera);

	/* Cancel and signal as complete all waiting requests. */
	while (!waitingRequests_.empty()) {
		Request *request = waitingRequests_.front();
		waitingRequests_.pop();

		request->_d()->cancel();
		completeRequest(request);
	}

	/* Make sure no requests are pending. */
	Camera::Private *data = camera->_d();
	ASSERT(data->queuedRequests_.empty());

	data->requestSequence_ = 0;
}

/**
 * \fn PipelineHandler::stopDevice()
 * \brief Stop capturing from all running streams
 * \param[in] camera The camera to stop
 *
 * This function stops capturing and processing requests immediately. All
 * pending requests are cancelled and complete immediately in an error state.
 */

/**
 * \brief Determine if the camera has any requests pending
 * \param[in] camera The camera to check
 *
 * This function determines if there are any requests queued to the pipeline
 * awaiting processing.
 *
 * \return True if there are pending requests, or false otherwise
 */
bool PipelineHandler::hasPendingRequests(const Camera *camera) const
{
	return !camera->_d()->queuedRequests_.empty();
}

/**
 * \fn PipelineHandler::registerRequest()
 * \brief Register a request for use by the pipeline handler
 * \param[in] request The request to register
 *
 * This function is called when the request is created, and allows the pipeline
 * handler to perform any one-time initialization it requries for the request.
 */
void PipelineHandler::registerRequest(Request *request)
{
	/*
	 * Connect the request prepared signal to notify the pipeline handler
	 * when a request is ready to be processed.
	 */
	request->_d()->prepared.connect(this, &PipelineHandler::doQueueRequests);
}

/**
 * \fn PipelineHandler::queueRequest()
 * \brief Queue a request
 * \param[in] request The request to queue
 *
 * This function queues a capture request to the pipeline handler for
 * processing. The request is first added to the internal list of waiting
 * requests which have to be prepared to make sure they are ready for being
 * queued to the pipeline handler.
 *
 * The queue of waiting requests is iterated and all prepared requests are
 * passed to the pipeline handler in the same order they have been queued by
 * calling this function.
 *
 * If a Request fails during the preparation phase or if the pipeline handler
 * fails in queuing the request to the hardware the request is cancelled.
 *
 * Keeping track of queued requests ensures automatic completion of all requests
 * when the pipeline handler is stopped with stop(). Request completion shall be
 * signalled by the pipeline handler using the completeRequest() function.
 *
 * \context This function is called from the CameraManager thread.
 */
void PipelineHandler::queueRequest(Request *request)
{
	LIBCAMERA_TRACEPOINT(request_queue, request);

	waitingRequests_.push(request);

	request->_d()->prepare(300ms);
}

/**
 * \brief Queue one requests to the device
 */
void PipelineHandler::doQueueRequest(Request *request)
{
	LIBCAMERA_TRACEPOINT(request_device_queue, request);

	Camera *camera = request->_d()->camera();
	Camera::Private *data = camera->_d();
	data->queuedRequests_.push_back(request);

	request->_d()->sequence_ = data->requestSequence_++;

	if (request->_d()->cancelled_) {
		completeRequest(request);
		return;
	}

	int ret = queueRequestDevice(camera, request);
	if (ret) {
		request->_d()->cancel();
		completeRequest(request);
	}
}

/**
 * \brief Queue prepared requests to the device
 *
 * Iterate the list of waiting requests and queue them to the device one
 * by one if they have been prepared.
 */
void PipelineHandler::doQueueRequests()
{
	while (!waitingRequests_.empty()) {
		Request *request = waitingRequests_.front();
		if (!request->_d()->prepared_)
			break;

		doQueueRequest(request);
		waitingRequests_.pop();
	}
}

/**
 * \fn PipelineHandler::queueRequestDevice()
 * \brief Queue a request to the device
 * \param[in] camera The camera to queue the request to
 * \param[in] request The request to queue
 *
 * This function queues a capture request to the device for processing. The
 * request contains a set of buffers associated with streams and a set of
 * parameters. The pipeline handler shall program the device to ensure that the
 * parameters will be applied to the frames captured in the buffers provided in
 * the request.
 *
 * \context This function is called from the CameraManager thread.
 *
 * \return 0 on success or a negative error code otherwise
 */

/**
 * \brief Complete a buffer for a request
 * \param[in] request The request the buffer belongs to
 * \param[in] buffer The buffer that has completed
 *
 * This function shall be called by pipeline handlers to signal completion of
 * the \a buffer part of the \a request. It notifies applications of buffer
 * completion and updates the request's internal buffer tracking. The request
 * is not completed automatically when the last buffer completes to give
 * pipeline handlers a chance to perform any operation that may still be
 * needed. They shall complete requests explicitly with completeRequest().
 *
 * \context This function shall be called from the CameraManager thread.
 *
 * \return True if all buffers contained in the request have completed, false
 * otherwise
 */
bool PipelineHandler::completeBuffer(Request *request, FrameBuffer *buffer)
{
	Camera *camera = request->_d()->camera();
	camera->bufferCompleted.emit(request, buffer);
	return request->_d()->completeBuffer(buffer);
}

/**
 * \brief Signal request completion
 * \param[in] request The request that has completed
 *
 * The pipeline handler shall call this function to notify the \a camera that
 * the request has completed. The request is no longer managed by the pipeline
 * handler and shall not be accessed once this function returns.
 *
 * This function ensures that requests will be returned to the application in
 * submission order, the pipeline handler may call it on any complete request
 * without any ordering constraint.
 *
 * \context This function shall be called from the CameraManager thread.
 */
void PipelineHandler::completeRequest(Request *request)
{
	Camera *camera = request->_d()->camera();

	request->_d()->complete();

	Camera::Private *data = camera->_d();

	while (!data->queuedRequests_.empty()) {
		Request *req = data->queuedRequests_.front();
		if (req->status() == Request::RequestPending)
			break;

		ASSERT(!req->hasPendingBuffers());
		data->queuedRequests_.pop_front();
		camera->requestComplete(req);
	}
}

/**
 * \brief Register a camera to the camera manager and pipeline handler
 * \param[in] camera The camera to be added
 *
 * This function is called by pipeline handlers to register the cameras they
 * handle with the camera manager.
 *
 * \context This function shall be called from the CameraManager thread.
 */
void PipelineHandler::registerCamera(std::shared_ptr<Camera> camera)
{
	cameras_.push_back(camera);

	if (mediaDevices_.empty())
		LOG(Pipeline, Fatal)
			<< "Registering camera with no media devices!";

	/*
	 * Walk the entity list and map the devnums of all capture video nodes
	 * to the camera.
	 */
	std::vector<dev_t> devnums;
	for (const std::shared_ptr<MediaDevice> &media : mediaDevices_) {
		for (const MediaEntity *entity : media->entities()) {
			if (entity->pads().size() == 1 &&
			    (entity->pads()[0]->flags() & MEDIA_PAD_FL_SINK) &&
			    entity->function() == MEDIA_ENT_F_IO_V4L) {
				devnums.push_back(makedev(entity->deviceMajor(),
							  entity->deviceMinor()));
			}
		}
	}

	manager_->addCamera(std::move(camera), devnums);
}

/**
 * \brief Enable hotplug handling for a media device
 * \param[in] media The media device
 *
 * This function enables hotplug handling, and especially hot-unplug handling,
 * of the \a media device. It shall be called by pipeline handlers for all the
 * media devices that can be disconnected.
 *
 * When a media device passed to this function is later unplugged, the pipeline
 * handler gets notified and automatically disconnects all the cameras it has
 * registered without requiring any manual intervention.
 */
void PipelineHandler::hotplugMediaDevice(MediaDevice *media)
{
	media->disconnected.connect(this, [=]() { mediaDeviceDisconnected(media); });
}

/**
 * \brief Slot for the MediaDevice disconnected signal
 */
void PipelineHandler::mediaDeviceDisconnected(MediaDevice *media)
{
	media->disconnected.disconnect(this);

	if (cameras_.empty())
		return;

	disconnect();
}

/**
 * \brief Device disconnection handler
 *
 * This virtual function is called to notify the pipeline handler that the
 * device it handles has been disconnected. It notifies all cameras created by
 * the pipeline handler that they have been disconnected, and unregisters them
 * from the camera manager.
 *
 * The function can be overloaded by pipeline handlers to perform custom
 * operations at disconnection time. Any overloaded version shall call the
 * PipelineHandler::disconnect() base function for proper hot-unplug operation.
 */
void PipelineHandler::disconnect()
{
	/*
	 * Each camera holds a reference to its associated pipeline handler
	 * instance. Hence, when the last camera is dropped, the pipeline
	 * handler will get destroyed by the last manager_->removeCamera(camera)
	 * call in the loop below.
	 *
	 * This is acceptable as long as we make sure that the code path does not
	 * access any member of the (already destroyed) pipeline handler instance
	 * afterwards. Therefore, we move the cameras_ vector to a local temporary
	 * container to avoid accessing freed memory later i.e. to explicitly run
	 * cameras_.clear().
	 */
	std::vector<std::weak_ptr<Camera>> cameras{ std::move(cameras_) };

	for (std::weak_ptr<Camera> ptr : cameras) {
		std::shared_ptr<Camera> camera = ptr.lock();
		if (!camera)
			continue;

		camera->disconnect();
		manager_->removeCamera(camera);
	}
}

/**
 * \var PipelineHandler::manager_
 * \brief The Camera manager associated with the pipeline handler
 *
 * The camera manager pointer is stored in the pipeline handler for the
 * convenience of pipeline handler implementations. It remains valid and
 * constant for the whole lifetime of the pipeline handler.
 */

/**
 * \fn PipelineHandler::name()
 * \brief Retrieve the pipeline handler name
 * \context This function shall be \threadsafe.
 * \return The pipeline handler name
 */

/**
 * \class PipelineHandlerFactory
 * \brief Registration of PipelineHandler classes and creation of instances
 *
 * To facilitate discovery and instantiation of PipelineHandler classes, the
 * PipelineHandlerFactory class maintains a registry of pipeline handler
 * classes. Each PipelineHandler subclass shall register itself using the
 * REGISTER_PIPELINE_HANDLER() macro, which will create a corresponding
 * instance of a PipelineHandlerFactory subclass and register it with the
 * static list of factories.
 */

/**
 * \brief Construct a pipeline handler factory
 * \param[in] name Name of the pipeline handler class
 *
 * Creating an instance of the factory registers is with the global list of
 * factories, accessible through the factories() function.
 *
 * The factory \a name is used for debug purpose and shall be unique.
 */
PipelineHandlerFactory::PipelineHandlerFactory(const char *name)
	: name_(name)
{
	registerType(this);
}

/**
 * \brief Create an instance of the PipelineHandler corresponding to the factory
 * \param[in] manager The camera manager
 *
 * \return A shared pointer to a new instance of the PipelineHandler subclass
 * corresponding to the factory
 */
std::shared_ptr<PipelineHandler> PipelineHandlerFactory::create(CameraManager *manager)
{
	PipelineHandler *handler = createInstance(manager);
	handler->name_ = name_.c_str();
	return std::shared_ptr<PipelineHandler>(handler);
}

/**
 * \fn PipelineHandlerFactory::name()
 * \brief Retrieve the factory name
 * \return The factory name
 */

/**
 * \brief Add a pipeline handler class to the registry
 * \param[in] factory Factory to use to construct the pipeline handler
 *
 * The caller is responsible to guarantee the uniqueness of the pipeline handler
 * name.
 */
void PipelineHandlerFactory::registerType(PipelineHandlerFactory *factory)
{
	std::vector<PipelineHandlerFactory *> &factories = PipelineHandlerFactory::factories();

	factories.push_back(factory);
}

/**
 * \brief Retrieve the list of all pipeline handler factories
 * \return the list of pipeline handler factories
 */
std::vector<PipelineHandlerFactory *> &PipelineHandlerFactory::factories()
{
	/*
	 * The static factories map is defined inside the function to ensure
	 * it gets initialized on first use, without any dependency on
	 * link order.
	 */
	static std::vector<PipelineHandlerFactory *> factories;
	return factories;
}

/**
 * \fn PipelineHandlerFactory::createInstance()
 * \brief Create an instance of the PipelineHandler corresponding to the factory
 * \param[in] manager The camera manager
 *
 * This virtual function is implemented by the REGISTER_PIPELINE_HANDLER()
 * macro. It creates a pipeline handler instance associated with the camera
 * \a manager.
 *
 * \return a pointer to a newly constructed instance of the PipelineHandler
 * subclass corresponding to the factory
 */

/**
 * \def REGISTER_PIPELINE_HANDLER
 * \brief Register a pipeline handler with the pipeline handler factory
 * \param[in] handler Class name of PipelineHandler derived class to register
 *
 * Register a PipelineHandler subclass with the factory and make it available to
 * try and match devices.
 */

} /* namespace libcamera */