/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
 * Copyright (C) 2019, Google Inc.
 *
 * ipu3.cpp - Pipeline handler for Intel IPU3
 */

#include <algorithm>
#include <iomanip>
#include <memory>
#include <queue>
#include <vector>

#include <linux/media-bus-format.h>

#include <libcamera/camera.h>
#include <libcamera/formats.h>
#include <libcamera/request.h>
#include <libcamera/stream.h>

#include "libcamera/internal/camera_sensor.h"
#include "libcamera/internal/device_enumerator.h"
#include "libcamera/internal/log.h"
#include "libcamera/internal/media_device.h"
#include "libcamera/internal/pipeline_handler.h"
#include "libcamera/internal/utils.h"
#include "libcamera/internal/v4l2_controls.h"
#include "libcamera/internal/v4l2_subdevice.h"
#include "libcamera/internal/v4l2_videodevice.h"

#include "cio2.h"

namespace libcamera {

LOG_DEFINE_CATEGORY(IPU3)

class IPU3CameraData;

class ImgUDevice
{
public:
	static constexpr unsigned int PAD_INPUT = 0;
	static constexpr unsigned int PAD_OUTPUT = 2;
	static constexpr unsigned int PAD_VF = 3;
	static constexpr unsigned int PAD_STAT = 4;

	/* ImgU output descriptor: group data specific to an ImgU output. */
	struct ImgUOutput {
		V4L2VideoDevice *dev;
		unsigned int pad;
		std::string name;
	};

	ImgUDevice()
		: imgu_(nullptr), input_(nullptr)
	{
		output_.dev = nullptr;
		viewfinder_.dev = nullptr;
		stat_.dev = nullptr;
	}

	~ImgUDevice()
	{
		delete imgu_;
		delete input_;
		delete output_.dev;
		delete viewfinder_.dev;
		delete stat_.dev;
	}

	int init(MediaDevice *media, unsigned int index);
	int configureInput(const Size &size,
			   V4L2DeviceFormat *inputFormat);
	int configureOutput(ImgUOutput *output,
			    const StreamConfiguration &cfg,
			    V4L2DeviceFormat *outputFormat);

	int allocateBuffers(IPU3CameraData *data, unsigned int bufferCount);
	void freeBuffers(IPU3CameraData *data);

	int start();
	int stop();

	int linkSetup(const std::string &source, unsigned int sourcePad,
		      const std::string &sink, unsigned int sinkPad,
		      bool enable);
	int enableLinks(bool enable);

	unsigned int index_;
	std::string name_;
	MediaDevice *media_;

	V4L2Subdevice *imgu_;
	V4L2VideoDevice *input_;
	ImgUOutput output_;
	ImgUOutput viewfinder_;
	ImgUOutput stat_;
	/* \todo Add param video device for 3A tuning */
};

class IPU3Stream : public Stream
{
public:
	IPU3Stream()
		: active_(false), raw_(false), device_(nullptr)
	{
	}

	bool active_;
	bool raw_;
	ImgUDevice::ImgUOutput *device_;
};

class IPU3CameraData : public CameraData
{
public:
	IPU3CameraData(PipelineHandler *pipe)
		: CameraData(pipe)
	{
	}

	void imguOutputBufferReady(FrameBuffer *buffer);
	void cio2BufferReady(FrameBuffer *buffer);

	CIO2Device cio2_;
	ImgUDevice *imgu_;

	IPU3Stream outStream_;
	IPU3Stream vfStream_;
	IPU3Stream rawStream_;
};

class IPU3CameraConfiguration : public CameraConfiguration
{
public:
	IPU3CameraConfiguration(Camera *camera, IPU3CameraData *data);

	Status validate() override;

	const StreamConfiguration &cio2Format() const { return cio2Configuration_; };
	const std::vector<const IPU3Stream *> &streams() { return streams_; }

private:
	static constexpr unsigned int IPU3_BUFFER_COUNT = 4;
	static constexpr unsigned int IPU3_MAX_STREAMS = 3;

	void assignStreams();
	void adjustStream(StreamConfiguration &cfg, bool scale);

	/*
	 * The IPU3CameraData instance is guaranteed to be valid as long as the
	 * corresponding Camera instance is valid. In order to borrow a
	 * reference to the camera data, store a new reference to the camera.
	 */
	std::shared_ptr<Camera> camera_;
	const IPU3CameraData *data_;

	StreamConfiguration cio2Configuration_;
	std::vector<const IPU3Stream *> streams_;
};

class PipelineHandlerIPU3 : public PipelineHandler
{
public:
	static constexpr unsigned int V4L2_CID_IPU3_PIPE_MODE = 0x009819c1;

	enum IPU3PipeModes {
		IPU3PipeModeVideo = 0,
		IPU3PipeModeStillCapture = 1,
	};

	PipelineHandlerIPU3(CameraManager *manager);

	CameraConfiguration *generateConfiguration(Camera *camera,
		const StreamRoles &roles) override;
	int configure(Camera *camera, CameraConfiguration *config) override;

	int exportFrameBuffers(Camera *camera, Stream *stream,
			       std::vector<std::unique_ptr<FrameBuffer>> *buffers) override;

	int start(Camera *camera) override;
	void stop(Camera *camera) override;

	int queueRequestDevice(Camera *camera, Request *request) override;

	bool match(DeviceEnumerator *enumerator) override;

private:
	IPU3CameraData *cameraData(const Camera *camera)
	{
		return static_cast<IPU3CameraData *>(
			PipelineHandler::cameraData(camera));
	}

	int registerCameras();

	int allocateBuffers(Camera *camera);
	int freeBuffers(Camera *camera);

	ImgUDevice imgu0_;
	ImgUDevice imgu1_;
	MediaDevice *cio2MediaDev_;
	MediaDevice *imguMediaDev_;
};

IPU3CameraConfiguration::IPU3CameraConfiguration(Camera *camera,
						 IPU3CameraData *data)
	: CameraConfiguration()
{
	camera_ = camera->shared_from_this();
	data_ = data;
}

void IPU3CameraConfiguration::assignStreams()
{
	/*
	 * Verify and update all configuration entries, and assign a stream to
	 * each of them. The viewfinder stream can scale, while the output
	 * stream can crop only, so select the output stream when the requested
	 * resolution is equal to the sensor resolution, and the viewfinder
	 * stream otherwise.
	 */
	std::set<const IPU3Stream *> availableStreams = {
		&data_->outStream_,
		&data_->vfStream_,
		&data_->rawStream_,
	};

	/*
	 * The caller is responsible to limit the number of requested streams
	 * to a number supported by the pipeline before calling this function.
	 */
	ASSERT(availableStreams.size() >= config_.size());

	streams_.clear();
	streams_.reserve(config_.size());

	for (const StreamConfiguration &cfg : config_) {
		const PixelFormatInfo &info =
			PixelFormatInfo::info(cfg.pixelFormat);
		const IPU3Stream *stream;

		if (info.colourEncoding == PixelFormatInfo::ColourEncodingRAW)
			stream = &data_->rawStream_;
		else if (cfg.size == cio2Configuration_.size)
			stream = &data_->outStream_;
		else
			stream = &data_->vfStream_;

		if (availableStreams.find(stream) == availableStreams.end())
			stream = *availableStreams.begin();

		streams_.push_back(stream);
		availableStreams.erase(stream);
	}
}

void IPU3CameraConfiguration::adjustStream(StreamConfiguration &cfg, bool scale)
{
	/* The only pixel format the driver supports is NV12. */
	cfg.pixelFormat = formats::NV12;

	if (scale) {
		/*
		 * Provide a suitable default that matches the sensor aspect
		 * ratio.
		 */
		if (!cfg.size.width || !cfg.size.height) {
			cfg.size.width = 1280;
			cfg.size.height = 1280 * cio2Configuration_.size.height
					/ cio2Configuration_.size.width;
		}

		/*
		 * \todo: Clamp the size to the hardware bounds when we will
		 * figure them out.
		 *
		 * \todo: Handle the scaler (BDS) restrictions. The BDS can
		 * only scale with the same factor in both directions, and the
		 * scaling factor is limited to a multiple of 1/32. At the
		 * moment the ImgU driver hides these constraints by applying
		 * additional cropping, this should be fixed on the driver
		 * side, and cropping should be exposed to us.
		 */
	} else {
		/*
		 * \todo: Properly support cropping when the ImgU driver
		 * interface will be cleaned up.
		 */
		cfg.size = cio2Configuration_.size;
	}

	/*
	 * Clamp the size to match the ImgU alignment constraints. The width
	 * shall be a multiple of 8 pixels and the height a multiple of 4
	 * pixels.
	 */
	if (cfg.size.width % 8 || cfg.size.height % 4) {
		cfg.size.width &= ~7;
		cfg.size.height &= ~3;
	}
}

CameraConfiguration::Status IPU3CameraConfiguration::validate()
{
	Status status = Valid;

	if (config_.empty())
		return Invalid;

	/* Cap the number of entries to the available streams. */
	if (config_.size() > IPU3_MAX_STREAMS) {
		config_.resize(IPU3_MAX_STREAMS);
		status = Adjusted;
	}

	/*
	 * Select the sensor format by collecting the maximum width and height
	 * and picking the closest larger match, as the IPU3 can downscale
	 * only. If no resolution is requested for any stream, or if no sensor
	 * resolution is large enough, pick the largest one.
	 */
	Size size = {};

	for (const StreamConfiguration &cfg : config_) {
		if (cfg.size.width > size.width)
			size.width = cfg.size.width;
		if (cfg.size.height > size.height)
			size.height = cfg.size.height;
	}

	/* Generate raw configuration from CIO2. */
	cio2Configuration_ = data_->cio2_.generateConfiguration(size);
	if (!cio2Configuration_.pixelFormat.isValid())
		return Invalid;

	/* Assign streams to each configuration entry. */
	assignStreams();

	/* Verify and adjust configuration if needed. */
	for (unsigned int i = 0; i < config_.size(); ++i) {
		StreamConfiguration &cfg = config_[i];
		const StreamConfiguration oldCfg = cfg;
		const IPU3Stream *stream = streams_[i];

		if (stream->raw_) {
			cfg = cio2Configuration_;
		} else {
			bool scale = stream == &data_->vfStream_;
			adjustStream(config_[i], scale);
			cfg.bufferCount = IPU3_BUFFER_COUNT;
		}

		if (cfg.pixelFormat != oldCfg.pixelFormat ||
		    cfg.size != oldCfg.size) {
			LOG(IPU3, Debug)
				<< "Stream " << i << " configuration adjusted to "
				<< cfg.toString();
			status = Adjusted;
		}
	}

	return status;
}

PipelineHandlerIPU3::PipelineHandlerIPU3(CameraManager *manager)
	: PipelineHandler(manager), cio2MediaDev_(nullptr), imguMediaDev_(nullptr)
{
}

CameraConfiguration *PipelineHandlerIPU3::generateConfiguration(Camera *camera,
	const StreamRoles &roles)
{
	IPU3CameraData *data = cameraData(camera);
	IPU3CameraConfiguration *config;
	std::set<IPU3Stream *> streams = {
		&data->outStream_,
		&data->vfStream_,
		&data->rawStream_,
	};

	config = new IPU3CameraConfiguration(camera, data);

	for (const StreamRole role : roles) {
		StreamConfiguration cfg = {};
		IPU3Stream *stream = nullptr;

		cfg.pixelFormat = formats::NV12;

		switch (role) {
		case StreamRole::StillCapture:
			/*
			 * Pick the output stream by default as the Viewfinder
			 * and VideoRecording roles are not allowed on
			 * the output stream.
			 */
			if (streams.find(&data->outStream_) != streams.end()) {
				stream = &data->outStream_;
			} else if (streams.find(&data->vfStream_) != streams.end()) {
				stream = &data->vfStream_;
			} else {
				LOG(IPU3, Error)
					<< "No stream available for requested role "
					<< role;
				break;
			}

			/*
			 * FIXME: Soraka: the maximum resolution reported by
			 * both sensors (2592x1944 for ov5670 and 4224x3136 for
			 * ov13858) are returned as default configurations but
			 * they're not correctly processed by the ImgU.
			 * Resolutions up tp 2560x1920 have been validated.
			 *
			 * \todo Clarify ImgU alignment requirements.
			 */
			cfg.size = { 2560, 1920 };

			break;

		case StreamRole::StillCaptureRaw: {
			if (streams.find(&data->rawStream_) == streams.end()) {
				LOG(IPU3, Error)
					<< "No stream available for requested role "
					<< role;
				break;
			}

			stream = &data->rawStream_;

			cfg.size = data->cio2_.sensor()->resolution();

			cfg = data->cio2_.generateConfiguration(cfg.size);
			break;
		}

		case StreamRole::Viewfinder:
		case StreamRole::VideoRecording: {
			/*
			 * We can't use the 'output' stream for viewfinder or
			 * video capture roles.
			 *
			 * \todo This is an artificial limitation until we
			 * figure out the exact capabilities of the hardware.
			 */
			if (streams.find(&data->vfStream_) == streams.end()) {
				LOG(IPU3, Error)
					<< "No stream available for requested role "
					<< role;
				break;
			}

			stream = &data->vfStream_;

			/*
			 * Align the default viewfinder size to the maximum
			 * available sensor resolution and to the IPU3
			 * alignment constraints.
			 */
			const Size &res = data->cio2_.sensor()->resolution();
			unsigned int width = std::min(1280U, res.width);
			unsigned int height = std::min(720U, res.height);
			cfg.size = { width & ~7, height & ~3 };

			break;
		}

		default:
			LOG(IPU3, Error)
				<< "Requested stream role not supported: " << role;
			break;
		}

		if (!stream) {
			delete config;
			return nullptr;
		}

		streams.erase(stream);

		config->addConfiguration(cfg);
	}

	config->validate();

	return config;
}

int PipelineHandlerIPU3::configure(Camera *camera, CameraConfiguration *c)
{
	IPU3CameraConfiguration *config =
		static_cast<IPU3CameraConfiguration *>(c);
	IPU3CameraData *data = cameraData(camera);
	IPU3Stream *outStream = &data->outStream_;
	IPU3Stream *vfStream = &data->vfStream_;
	CIO2Device *cio2 = &data->cio2_;
	ImgUDevice *imgu = data->imgu_;
	V4L2DeviceFormat outputFormat;
	int ret;

	/*
	 * FIXME: enabled links in one ImgU pipe interfere with capture
	 * operations on the other one. This can be easily triggered by
	 * capturing from one camera and then trying to capture from the other
	 * one right after, without disabling media links on the first used
	 * pipe.
	 *
	 * The tricky part here is where to disable links on the ImgU instance
	 * which is currently not in use:
	 * 1) Link enable/disable cannot be done at start()/stop() time as video
	 * devices needs to be linked first before format can be configured on
	 * them.
	 * 2) As link enable has to be done at the least in configure(),
	 * before configuring formats, the only place where to disable links
	 * would be 'stop()', but the Camera class state machine allows
	 * start()<->stop() sequences without any configure() in between.
	 *
	 * As of now, disable all links in the ImgU media graph before
	 * configuring the device, to allow alternate the usage of the two
	 * ImgU pipes.
	 *
	 * As a consequence, a Camera using an ImgU shall be configured before
	 * any start()/stop() sequence. An application that wants to
	 * pre-configure all the camera and then start/stop them alternatively
	 * without going through any re-configuration (a sequence that is
	 * allowed by the Camera state machine) would now fail on the IPU3.
	 */
	ret = imguMediaDev_->disableLinks();
	if (ret)
		return ret;

	/*
	 * \todo: Enable links selectively based on the requested streams.
	 * As of now, enable all links unconditionally.
	 * \todo Don't configure the ImgU at all if we only have a single
	 * stream which is for raw capture, in which case no buffers will
	 * ever be queued to the ImgU.
	 */
	ret = data->imgu_->enableLinks(true);
	if (ret)
		return ret;

	/*
	 * Pass the requested stream size to the CIO2 unit and get back the
	 * adjusted format to be propagated to the ImgU output devices.
	 */
	const Size &sensorSize = config->cio2Format().size;
	V4L2DeviceFormat cio2Format = {};
	ret = cio2->configure(sensorSize, &cio2Format);
	if (ret)
		return ret;

	ret = imgu->configureInput(sensorSize, &cio2Format);
	if (ret)
		return ret;

	/* Apply the format to the configured streams output devices. */
	outStream->active_ = false;
	vfStream->active_ = false;

	for (unsigned int i = 0; i < config->size(); ++i) {
		/*
		 * Use a const_cast<> here instead of storing a mutable stream
		 * pointer in the configuration to let the compiler catch
		 * unwanted modifications of camera data in the configuration
		 * validate() implementation.
		 */
		IPU3Stream *stream = const_cast<IPU3Stream *>(config->streams()[i]);
		StreamConfiguration &cfg = (*config)[i];

		stream->active_ = true;
		cfg.setStream(stream);

		/*
		 * The RAW still capture stream just copies buffers from the
		 * internal queue and doesn't need any specific configuration.
		 */
		if (stream->raw_) {
			cfg.stride = cio2Format.planes[0].bpl;
		} else {
			ret = imgu->configureOutput(stream->device_, cfg,
						    &outputFormat);
			if (ret)
				return ret;

			cfg.stride = outputFormat.planes[0].bpl;
		}
	}

	/*
	 * As we need to set format also on the non-active streams, use
	 * the configuration of the active one for that purpose (there should
	 * be at least one active stream in the configuration request).
	 */
	if (!outStream->active_) {
		ret = imgu->configureOutput(outStream->device_, config->at(0),
					    &outputFormat);
		if (ret)
			return ret;
	}

	if (!vfStream->active_) {
		ret = imgu->configureOutput(vfStream->device_, config->at(0),
					    &outputFormat);
		if (ret)
			return ret;
	}

	/*
	 * Apply the largest available format to the stat node.
	 * \todo Revise this when we'll actually use the stat node.
	 */
	StreamConfiguration statCfg = {};
	statCfg.size = cio2Format.size;

	ret = imgu->configureOutput(&imgu->stat_, statCfg, &outputFormat);
	if (ret)
		return ret;

	/* Apply the "pipe_mode" control to the ImgU subdevice. */
	ControlList ctrls(imgu->imgu_->controls());
	ctrls.set(V4L2_CID_IPU3_PIPE_MODE,
		  static_cast<int32_t>(vfStream->active_ ? IPU3PipeModeVideo :
				       IPU3PipeModeStillCapture));
	ret = imgu->imgu_->setControls(&ctrls);
	if (ret) {
		LOG(IPU3, Error) << "Unable to set pipe_mode control";
		return ret;
	}

	return 0;
}

int PipelineHandlerIPU3::exportFrameBuffers(Camera *camera, Stream *stream,
					    std::vector<std::unique_ptr<FrameBuffer>> *buffers)
{
	IPU3CameraData *data = cameraData(camera);
	IPU3Stream *ipu3stream = static_cast<IPU3Stream *>(stream);
	unsigned int count = stream->configuration().bufferCount;

	if (ipu3stream->raw_)
		return data->cio2_.exportBuffers(count, buffers);

	return ipu3stream->device_->dev->exportBuffers(count, buffers);
}

/**
 * \todo Clarify if 'viewfinder' and 'stat' nodes have to be set up and
 * started even if not in use. As of now, if not properly configured and
 * enabled, the ImgU processing pipeline stalls.
 *
 * In order to be able to start the 'viewfinder' and 'stat' nodes, we need
 * memory to be reserved.
 */
int PipelineHandlerIPU3::allocateBuffers(Camera *camera)
{
	IPU3CameraData *data = cameraData(camera);
	ImgUDevice *imgu = data->imgu_;
	unsigned int bufferCount;
	int ret;

	bufferCount = std::max({
		data->outStream_.configuration().bufferCount,
		data->vfStream_.configuration().bufferCount,
		data->rawStream_.configuration().bufferCount,
	});

	ret = imgu->allocateBuffers(data, bufferCount);
	if (ret < 0)
		return ret;

	return 0;
}

int PipelineHandlerIPU3::freeBuffers(Camera *camera)
{
	IPU3CameraData *data = cameraData(camera);

	data->imgu_->freeBuffers(data);

	return 0;
}

int PipelineHandlerIPU3::start(Camera *camera)
{
	IPU3CameraData *data = cameraData(camera);
	CIO2Device *cio2 = &data->cio2_;
	ImgUDevice *imgu = data->imgu_;
	int ret;

	/* Allocate buffers for internal pipeline usage. */
	ret = allocateBuffers(camera);
	if (ret)
		return ret;

	/*
	 * Start the ImgU video devices, buffers will be queued to the
	 * ImgU output and viewfinder when requests will be queued.
	 */
	ret = cio2->start();
	if (ret)
		goto error;

	ret = imgu->start();
	if (ret) {
		imgu->stop();
		cio2->stop();
		goto error;
	}

	return 0;

error:
	freeBuffers(camera);
	LOG(IPU3, Error) << "Failed to start camera " << camera->name();

	return ret;
}

void PipelineHandlerIPU3::stop(Camera *camera)
{
	IPU3CameraData *data = cameraData(camera);
	int ret = 0;

	ret |= data->imgu_->stop();
	ret |= data->cio2_.stop();
	if (ret)
		LOG(IPU3, Warning) << "Failed to stop camera "
				   << camera->name();

	freeBuffers(camera);
}

int PipelineHandlerIPU3::queueRequestDevice(Camera *camera, Request *request)
{
	IPU3CameraData *data = cameraData(camera);
	int error = 0;

	/*
	 * Queue a buffer on the CIO2, using the raw stream buffer provided in
	 * the request, if any, or a CIO2 internal buffer otherwise.
	 */
	FrameBuffer *rawBuffer = request->findBuffer(&data->rawStream_);
	error = data->cio2_.queueBuffer(request, rawBuffer);
	if (error)
		return error;

	/* Queue all buffers from the request aimed for the ImgU. */
	for (auto it : request->buffers()) {
		IPU3Stream *stream = static_cast<IPU3Stream *>(it.first);
		if (stream->raw_)
			continue;

		FrameBuffer *buffer = it.second;
		int ret = stream->device_->dev->queueBuffer(buffer);
		if (ret < 0)
			error = ret;
	}

	return error;
}

bool PipelineHandlerIPU3::match(DeviceEnumerator *enumerator)
{
	int ret;

	DeviceMatch cio2_dm("ipu3-cio2");
	cio2_dm.add("ipu3-csi2 0");
	cio2_dm.add("ipu3-cio2 0");
	cio2_dm.add("ipu3-csi2 1");
	cio2_dm.add("ipu3-cio2 1");
	cio2_dm.add("ipu3-csi2 2");
	cio2_dm.add("ipu3-cio2 2");
	cio2_dm.add("ipu3-csi2 3");
	cio2_dm.add("ipu3-cio2 3");

	DeviceMatch imgu_dm("ipu3-imgu");
	imgu_dm.add("ipu3-imgu 0");
	imgu_dm.add("ipu3-imgu 0 input");
	imgu_dm.add("ipu3-imgu 0 parameters");
	imgu_dm.add("ipu3-imgu 0 output");
	imgu_dm.add("ipu3-imgu 0 viewfinder");
	imgu_dm.add("ipu3-imgu 0 3a stat");
	imgu_dm.add("ipu3-imgu 1");
	imgu_dm.add("ipu3-imgu 1 input");
	imgu_dm.add("ipu3-imgu 1 parameters");
	imgu_dm.add("ipu3-imgu 1 output");
	imgu_dm.add("ipu3-imgu 1 viewfinder");
	imgu_dm.add("ipu3-imgu 1 3a stat");

	cio2MediaDev_ = acquireMediaDevice(enumerator, cio2_dm);
	if (!cio2MediaDev_)
		return false;

	imguMediaDev_ = acquireMediaDevice(enumerator, imgu_dm);
	if (!imguMediaDev_)
		return false;

	/*
	 * Disable all links that are enabled by default on CIO2, as camera
	 * creation enables all valid links it finds.
	 */
	if (cio2MediaDev_->disableLinks())
		return false;

	ret = imguMediaDev_->disableLinks();
	if (ret)
		return ret;

	ret = registerCameras();

	return ret == 0;
}

/**
 * \brief Initialise ImgU and CIO2 devices associated with cameras
 *
 * Initialise the two ImgU instances and create cameras with an associated
 * CIO2 device instance.
 *
 * \return 0 on success or a negative error code for error or if no camera
 * has been created
 * \retval -ENODEV no camera has been created
 */
int PipelineHandlerIPU3::registerCameras()
{
	int ret;

	ret = imgu0_.init(imguMediaDev_, 0);
	if (ret)
		return ret;

	ret = imgu1_.init(imguMediaDev_, 1);
	if (ret)
		return ret;

	/*
	 * For each CSI-2 receiver on the IPU3, create a Camera if an
	 * image sensor is connected to it and the sensor can produce images
	 * in a compatible format.
	 */
	unsigned int numCameras = 0;
	for (unsigned int id = 0; id < 4 && numCameras < 2; ++id) {
		std::unique_ptr<IPU3CameraData> data =
			std::make_unique<IPU3CameraData>(this);
		std::set<Stream *> streams = {
			&data->outStream_,
			&data->vfStream_,
			&data->rawStream_,
		};
		CIO2Device *cio2 = &data->cio2_;

		ret = cio2->init(cio2MediaDev_, id);
		if (ret)
			continue;

		/* Initialize the camera properties. */
		data->properties_ = cio2->sensor()->properties();

		/**
		 * \todo Dynamically assign ImgU and output devices to each
		 * stream and camera; as of now, limit support to two cameras
		 * only, and assign imgu0 to the first one and imgu1 to the
		 * second.
		 */
		data->imgu_ = numCameras ? &imgu1_ : &imgu0_;
		data->outStream_.device_ = &data->imgu_->output_;
		data->vfStream_.device_ = &data->imgu_->viewfinder_;
		data->rawStream_.raw_ = true;

		/*
		 * Connect video devices' 'bufferReady' signals to their
		 * slot to implement the image processing pipeline.
		 *
		 * Frames produced by the CIO2 unit are passed to the
		 * associated ImgU input where they get processed and
		 * returned through the ImgU main and secondary outputs.
		 */
		data->cio2_.bufferReady.connect(data.get(),
					&IPU3CameraData::cio2BufferReady);
		data->imgu_->input_->bufferReady.connect(&data->cio2_,
					&CIO2Device::tryReturnBuffer);
		data->imgu_->output_.dev->bufferReady.connect(data.get(),
					&IPU3CameraData::imguOutputBufferReady);
		data->imgu_->viewfinder_.dev->bufferReady.connect(data.get(),
					&IPU3CameraData::imguOutputBufferReady);

		/* Create and register the Camera instance. */
		std::string cameraName = cio2->sensor()->entity()->name();
		std::shared_ptr<Camera> camera = Camera::create(this,
								cameraName,
								streams);

		registerCamera(std::move(camera), std::move(data));

		LOG(IPU3, Info)
			<< "Registered Camera[" << numCameras << "] \""
			<< cameraName << "\""
			<< " connected to CSI-2 receiver " << id;

		numCameras++;
	}

	return numCameras ? 0 : -ENODEV;
}

/* -----------------------------------------------------------------------------
 * Buffer Ready slots
 */

/**
 * \brief Handle buffers completion at the ImgU output
 * \param[in] buffer The completed buffer
 *
 * Buffers completed from the ImgU output are directed to the application.
 */
void IPU3CameraData::imguOutputBufferReady(FrameBuffer *buffer)
{
	Request *request = buffer->request();

	if (!pipe_->completeBuffer(camera_, request, buffer))
		/* Request not completed yet, return here. */
		return;

	/* Mark the request as complete. */
	pipe_->completeRequest(camera_, request);
}

/**
 * \brief Handle buffers completion at the CIO2 output
 * \param[in] buffer The completed buffer
 *
 * Buffers completed from the CIO2 are immediately queued to the ImgU unit
 * for further processing.
 */
void IPU3CameraData::cio2BufferReady(FrameBuffer *buffer)
{
	/* \todo Handle buffer failures when state is set to BufferError. */
	if (buffer->metadata().status == FrameMetadata::FrameCancelled)
		return;

	Request *request = buffer->request();

	/*
	 * If the request contains a buffer for the RAW stream only, complete it
	 * now as there's no need for ImgU processing.
	 */
	if (request->findBuffer(&rawStream_) &&
	    pipe_->completeBuffer(camera_, request, buffer)) {
		pipe_->completeRequest(camera_, request);
		return;
	}

	imgu_->input_->queueBuffer(buffer);
}

/* -----------------------------------------------------------------------------
 * ImgU Device
 */

/**
 * \brief Initialize components of the ImgU instance
 * \param[in] mediaDevice The ImgU instance media device
 * \param[in] index The ImgU instance index
 *
 * Create and open the V4L2 devices and subdevices of the ImgU instance
 * with \a index.
 *
 * In case of errors the created V4L2VideoDevice and V4L2Subdevice instances
 * are destroyed at pipeline handler delete time.
 *
 * \return 0 on success or a negative error code otherwise
 */
int ImgUDevice::init(MediaDevice *media, unsigned int index)
{
	int ret;

	index_ = index;
	name_ = "ipu3-imgu " + std::to_string(index_);
	media_ = media;

	/*
	 * The media entities presence in the media device has been verified
	 * by the match() function: no need to check for newly created
	 * video devices and subdevice validity here.
	 */
	imgu_ = V4L2Subdevice::fromEntityName(media, name_);
	ret = imgu_->open();
	if (ret)
		return ret;

	input_ = V4L2VideoDevice::fromEntityName(media, name_ + " input");
	ret = input_->open();
	if (ret)
		return ret;

	output_.dev = V4L2VideoDevice::fromEntityName(media, name_ + " output");
	ret = output_.dev->open();
	if (ret)
		return ret;

	output_.pad = PAD_OUTPUT;
	output_.name = "output";

	viewfinder_.dev = V4L2VideoDevice::fromEntityName(media,
							  name_ + " viewfinder");
	ret = viewfinder_.dev->open();
	if (ret)
		return ret;

	viewfinder_.pad = PAD_VF;
	viewfinder_.name = "viewfinder";

	stat_.dev = V4L2VideoDevice::fromEntityName(media, name_ + " 3a stat");
	ret = stat_.dev->open();
	if (ret)
		return ret;

	stat_.pad = PAD_STAT;
	stat_.name = "stat";

	return 0;
}

/**
 * \brief Configure the ImgU unit input
 * \param[in] size The ImgU input frame size
 * \param[in] inputFormat The format to be applied to ImgU input
 * \return 0 on success or a negative error code otherwise
 */
int ImgUDevice::configureInput(const Size &size,
			       V4L2DeviceFormat *inputFormat)
{
	/* Configure the ImgU input video device with the requested sizes. */
	int ret = input_->setFormat(inputFormat);
	if (ret)
		return ret;

	LOG(IPU3, Debug) << "ImgU input format = " << inputFormat->toString();

	/*
	 * \todo The IPU3 driver implementation shall be changed to use the
	 * input sizes as 'ImgU Input' subdevice sizes, and use the desired
	 * GDC output sizes to configure the crop/compose rectangles.
	 *
	 * The current IPU3 driver implementation uses GDC sizes as the
	 * 'ImgU Input' subdevice sizes, and the input video device sizes
	 * to configure the crop/compose rectangles, contradicting the
	 * V4L2 specification.
	 */
	Rectangle rect = {
		.x = 0,
		.y = 0,
		.width = inputFormat->size.width,
		.height = inputFormat->size.height,
	};
	ret = imgu_->setSelection(PAD_INPUT, V4L2_SEL_TGT_CROP, &rect);
	if (ret)
		return ret;

	ret = imgu_->setSelection(PAD_INPUT, V4L2_SEL_TGT_COMPOSE, &rect);
	if (ret)
		return ret;

	LOG(IPU3, Debug) << "ImgU input feeder and BDS rectangle = "
			 << rect.toString();

	V4L2SubdeviceFormat imguFormat = {};
	imguFormat.mbus_code = MEDIA_BUS_FMT_FIXED;
	imguFormat.size = size;

	ret = imgu_->setFormat(PAD_INPUT, &imguFormat);
	if (ret)
		return ret;

	LOG(IPU3, Debug) << "ImgU GDC format = " << imguFormat.toString();

	return 0;
}

/**
 * \brief Configure the ImgU unit \a id video output
 * \param[in] output The ImgU output device to configure
 * \param[in] cfg The requested configuration
 * \return 0 on success or a negative error code otherwise
 */
int ImgUDevice::configureOutput(ImgUOutput *output,
				const StreamConfiguration &cfg,
				V4L2DeviceFormat *outputFormat)
{
	V4L2VideoDevice *dev = output->dev;
	unsigned int pad = output->pad;

	V4L2SubdeviceFormat imguFormat = {};
	imguFormat.mbus_code = MEDIA_BUS_FMT_FIXED;
	imguFormat.size = cfg.size;

	int ret = imgu_->setFormat(pad, &imguFormat);
	if (ret)
		return ret;

	/* No need to apply format to the stat node. */
	if (output == &stat_)
		return 0;

	*outputFormat = {};
	outputFormat->fourcc = dev->toV4L2PixelFormat(formats::NV12);
	outputFormat->size = cfg.size;
	outputFormat->planesCount = 2;

	ret = dev->setFormat(outputFormat);
	if (ret)
		return ret;

	LOG(IPU3, Debug) << "ImgU " << output->name << " format = "
			 << outputFormat->toString();

	return 0;
}

/**
 * \brief Allocate buffers for all the ImgU video devices
 */
int ImgUDevice::allocateBuffers(IPU3CameraData *data, unsigned int bufferCount)
{
	/* Share buffers between CIO2 output and ImgU input. */
	int ret = input_->importBuffers(bufferCount);
	if (ret) {
		LOG(IPU3, Error) << "Failed to import ImgU input buffers";
		return ret;
	}

	/*
	 * The kernel fails to start if buffers are not either imported or
	 * allocated for the statistics video device. As statistics buffers are
	 * not yet used by the pipeline import buffers to save memory.
	 *
	 * \todo To be revised when we'll actually use the stat node.
	 */
	ret = stat_.dev->importBuffers(bufferCount);
	if (ret < 0) {
		LOG(IPU3, Error) << "Failed to allocate ImgU stat buffers";
		goto error;
	}

	/*
	 * Import buffers for all outputs, regardless of whether the
	 * corresponding stream is active or inactive, as the driver needs
	 * buffers to be requested on the V4L2 devices in order to operate.
	 */
	ret = output_.dev->importBuffers(bufferCount);
	if (ret < 0) {
		LOG(IPU3, Error) << "Failed to import ImgU output buffers";
		goto error;
	}

	ret = viewfinder_.dev->importBuffers(bufferCount);
	if (ret < 0) {
		LOG(IPU3, Error) << "Failed to import ImgU viewfinder buffers";
		goto error;
	}

	return 0;

error:
	freeBuffers(data);

	return ret;
}

/**
 * \brief Release buffers for all the ImgU video devices
 */
void ImgUDevice::freeBuffers(IPU3CameraData *data)
{
	int ret;

	ret = output_.dev->releaseBuffers();
	if (ret)
		LOG(IPU3, Error) << "Failed to release ImgU output buffers";

	ret = stat_.dev->releaseBuffers();
	if (ret)
		LOG(IPU3, Error) << "Failed to release ImgU stat buffers";

	ret = viewfinder_.dev->releaseBuffers();
	if (ret)
		LOG(IPU3, Error) << "Failed to release ImgU viewfinder buffers";

	ret = input_->releaseBuffers();
	if (ret)
		LOG(IPU3, Error) << "Failed to release ImgU input buffers";
}

int ImgUDevice::start()
{
	int ret;

	/* Start the ImgU video devices. */
	ret = output_.dev->streamOn();
	if (ret) {
		LOG(IPU3, Error) << "Failed to start ImgU output";
		return ret;
	}

	ret = viewfinder_.dev->streamOn();
	if (ret) {
		LOG(IPU3, Error) << "Failed to start ImgU viewfinder";
		return ret;
	}

	ret = stat_.dev->streamOn();
	if (ret) {
		LOG(IPU3, Error) << "Failed to start ImgU stat";
		return ret;
	}

	ret = input_->streamOn();
	if (ret) {
		LOG(IPU3, Error) << "Failed to start ImgU input";
		return ret;
	}

	return 0;
}

int ImgUDevice::stop()
{
	int ret;

	ret = output_.dev->streamOff();
	ret |= viewfinder_.dev->streamOff();
	ret |= stat_.dev->streamOff();
	ret |= input_->streamOff();

	return ret;
}

/**
 * \brief Enable or disable a single link on the ImgU instance
 *
 * This method assumes the media device associated with the ImgU instance
 * is open.
 *
 * \return 0 on success or a negative error code otherwise
 */
int ImgUDevice::linkSetup(const std::string &source, unsigned int sourcePad,
			  const std::string &sink, unsigned int sinkPad,
			  bool enable)
{
	MediaLink *link = media_->link(source, sourcePad, sink, sinkPad);
	if (!link) {
		LOG(IPU3, Error)
			<< "Failed to get link: '" << source << "':"
			<< sourcePad << " -> '" << sink << "':" << sinkPad;
		return -ENODEV;
	}

	return link->setEnabled(enable);
}

/**
 * \brief Enable or disable all media links in the ImgU instance to prepare
 * for capture operations
 *
 * \todo This method will probably be removed or changed once links will be
 * enabled or disabled selectively.
 *
 * \return 0 on success or a negative error code otherwise
 */
int ImgUDevice::enableLinks(bool enable)
{
	std::string viewfinderName = name_ + " viewfinder";
	std::string outputName = name_ + " output";
	std::string statName = name_ + " 3a stat";
	std::string inputName = name_ + " input";
	int ret;

	ret = linkSetup(inputName, 0, name_, PAD_INPUT, enable);
	if (ret)
		return ret;

	ret = linkSetup(name_, PAD_OUTPUT, outputName, 0, enable);
	if (ret)
		return ret;

	ret = linkSetup(name_, PAD_VF, viewfinderName, 0, enable);
	if (ret)
		return ret;

	return linkSetup(name_, PAD_STAT, statName, 0, enable);
}

REGISTER_PIPELINE_HANDLER(PipelineHandlerIPU3);

} /* namespace libcamera */