src/gstreamer

/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
 * Copyright (C) 2019-2023, Raspberry Pi Ltd
 *
 * pipeline_base.cpp - Pipeline handler base class for Raspberry Pi devices
 */

#include "pipeline_base.h"

#include <chrono>

#include <linux/media-bus-format.h>
#include <linux/videodev2.h>

#include <libcamera/base/file.h>
#include <libcamera/base/utils.h>

#include <libcamera/formats.h>
#include <libcamera/logging.h>
#include <libcamera/property_ids.h>

#include "libcamera/internal/camera_lens.h"
#include "libcamera/internal/ipa_manager.h"
#include "libcamera/internal/v4l2_subdevice.h"

using namespace std::chrono_literals;

namespace libcamera {

using namespace RPi;

LOG_DEFINE_CATEGORY(RPI)

using StreamFlag = RPi::Stream::StreamFlag;

namespace {

constexpr unsigned int defaultRawBitDepth = 12;

bool isRaw(const PixelFormat &pixFmt)
{
	/* This test works for both Bayer and raw mono formats. */
	return BayerFormat::fromPixelFormat(pixFmt).isValid();
}

PixelFormat mbusCodeToPixelFormat(unsigned int mbus_code,
				  BayerFormat::Packing packingReq)
{
	BayerFormat bayer = BayerFormat::fromMbusCode(mbus_code);

	ASSERT(bayer.isValid());

	bayer.packing = packingReq;
	PixelFormat pix = bayer.toPixelFormat();

	/*
	 * Not all formats (e.g. 8-bit or 16-bit Bayer formats) can have packed
	 * variants. So if the PixelFormat returns as invalid, use the non-packed
	 * conversion instead.
	 */
	if (!pix.isValid()) {
		bayer.packing = BayerFormat::Packing::None;
		pix = bayer.toPixelFormat();
	}

	return pix;
}

SensorFormats populateSensorFormats(std::unique_ptr<CameraSensor> &sensor)
{
	SensorFormats formats;

	for (auto const mbusCode : sensor->mbusCodes())
		formats.emplace(mbusCode, sensor->sizes(mbusCode));

	return formats;
}

bool isMonoSensor(std::unique_ptr<CameraSensor> &sensor)
{
	unsigned int mbusCode = sensor->mbusCodes()[0];
	const BayerFormat &bayer = BayerFormat::fromMbusCode(mbusCode);

	return bayer.order == BayerFormat::Order::MONO;
}

double scoreFormat(double desired, double actual)
{
	double score = desired - actual;
	/* Smaller desired dimensions are preferred. */
	if (score < 0.0)
		score = (-score) / 8;
	/* Penalise non-exact matches. */
	if (actual != desired)
		score *= 2;

	return score;
}

V4L2SubdeviceFormat findBestFormat(const SensorFormats &formatsMap, const Size &req, unsigned int bitDepth)
{
	double bestScore = std::numeric_limits<double>::max(), score;
	V4L2SubdeviceFormat bestFormat;
	bestFormat.colorSpace = ColorSpace::Raw;

	constexpr float penaltyAr = 1500.0;
	constexpr float penaltyBitDepth = 500.0;

	/* Calculate the closest/best mode from the user requested size. */
	for (const auto &iter : formatsMap) {
		const unsigned int mbusCode = iter.first;
		const PixelFormat format = mbusCodeToPixelFormat(mbusCode,
								 BayerFormat::Packing::None);
		const PixelFormatInfo &info = PixelFormatInfo::info(format);

		for (const Size &size : iter.second) {
			double reqAr = static_cast<double>(req.width) / req.height;
			double fmtAr = static_cast<double>(size.width) / size.height;

			/* Score the dimensions for closeness. */
			score = scoreFormat(req.width, size.width);
			score += scoreFormat(req.height, size.height);
			score += penaltyAr * scoreFormat(reqAr, fmtAr);

			/* Add any penalties... this is not an exact science! */
			score += utils::abs_diff(info.bitsPerPixel, bitDepth) * penaltyBitDepth;

			if (score <= bestScore) {
				bestScore = score;
				bestFormat.mbus_code = mbusCode;
				bestFormat.size = size;
			}

			LOG(RPI, Debug) << "Format: " << size
					<< " fmt " << format
					<< " Score: " << score
					<< " (best " << bestScore << ")";
		}
	}

	return bestFormat;
}

const std::vector<ColorSpace> validColorSpaces = {
	ColorSpace::Sycc,
	ColorSpace::Smpte170m,
	ColorSpace::Rec709
};

std::optional<ColorSpace> findValidColorSpace(const ColorSpace &colourSpace)
{
	for (auto cs : validColorSpaces) {
		if (colourSpace.primaries == cs.primaries &&
		    colourSpace.transferFunction == cs.transferFunction)
			return cs;
	}

	return std::nullopt;
}

bool isRgb(const PixelFormat &pixFmt)
{
	const PixelFormatInfo &info = PixelFormatInfo::info(pixFmt);
	return info.colourEncoding == PixelFormatInfo::ColourEncodingRGB;
}

bool isYuv(const PixelFormat &pixFmt)
{
	/* The code below would return true for raw mono streams, so weed those out first. */
	if (isRaw(pixFmt))
		return false;

	const PixelFormatInfo &info = PixelFormatInfo::info(pixFmt);
	return info.colourEncoding == PixelFormatInfo::ColourEncodingYUV;
}

} /* namespace */

/*
 * Raspberry Pi drivers expect the following colour spaces:
 * - V4L2_COLORSPACE_RAW for raw streams.
 * - One of V4L2_COLORSPACE_JPEG, V4L2_COLORSPACE_SMPTE170M, V4L2_COLORSPACE_REC709 for
 *   non-raw streams. Other fields such as transfer function, YCbCr encoding and
 *   quantisation are not used.
 *
 * The libcamera colour spaces that we wish to use corresponding to these are therefore:
 * - ColorSpace::Raw for V4L2_COLORSPACE_RAW
 * - ColorSpace::Sycc for V4L2_COLORSPACE_JPEG
 * - ColorSpace::Smpte170m for V4L2_COLORSPACE_SMPTE170M
 * - ColorSpace::Rec709 for V4L2_COLORSPACE_REC709
 */
CameraConfiguration::Status RPiCameraConfiguration::validateColorSpaces([[maybe_unused]] ColorSpaceFlags flags)
{
	Status status = Valid;
	yuvColorSpace_.reset();

	for (auto cfg : config_) {
		/* First fix up raw streams to have the "raw" colour space. */
		if (isRaw(cfg.pixelFormat)) {
			/* If there was no value here, that doesn't count as "adjusted". */
			if (cfg.colorSpace && cfg.colorSpace != ColorSpace::Raw)
				status = Adjusted;
			cfg.colorSpace = ColorSpace::Raw;
			continue;
		}

		/* Next we need to find our shared colour space. The first valid one will do. */
		if (cfg.colorSpace && !yuvColorSpace_)
			yuvColorSpace_ = findValidColorSpace(cfg.colorSpace.value());
	}

	/* If no colour space was given anywhere, choose sYCC. */
	if (!yuvColorSpace_)
		yuvColorSpace_ = ColorSpace::Sycc;

	/* Note the version of this that any RGB streams will have to use. */
	rgbColorSpace_ = yuvColorSpace_;
	rgbColorSpace_->ycbcrEncoding = ColorSpace::YcbcrEncoding::None;
	rgbColorSpace_->range = ColorSpace::Range::Full;

	/* Go through the streams again and force everyone to the same colour space. */
	for (auto cfg : config_) {
		if (cfg.colorSpace == ColorSpace::Raw)
			continue;

		if (isYuv(cfg.pixelFormat) && cfg.colorSpace != yuvColorSpace_) {
			/* Again, no value means "not adjusted". */
			if (cfg.colorSpace)
				status = Adjusted;
			cfg.colorSpace = yuvColorSpace_;
		}
		if (isRgb(cfg.pixelFormat) && cfg.colorSpace != rgbColorSpace_) {
			/* Be nice, and let the YUV version count as non-adjusted too. */
			if (cfg.colorSpace && cfg.colorSpace != yuvColorSpace_)
				status = Adjusted;
			cfg.colorSpace = rgbColorSpace_;
		}
	}

	return status;
}

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

	if (config_.empty())
		return Invalid;

	status = validateColorSpaces(ColorSpaceFlag::StreamsShareColorSpace);

	/*
	 * Validate the requested transform against the sensor capabilities and
	 * rotation and store the final combined transform that configure() will
	 * need to apply to the sensor to save us working it out again.
	 */
	Transform requestedTransform = transform;
	combinedTransform_ = data_->sensor_->validateTransform(&transform);
	if (transform != requestedTransform)
		status = Adjusted;

	std::vector<CameraData::StreamParams> rawStreams, outStreams;
	for (const auto &[index, cfg] : utils::enumerate(config_)) {
		if (isRaw(cfg.pixelFormat))
			rawStreams.emplace_back(index, &cfg);
		else
			outStreams.emplace_back(index, &cfg);
	}

	/* Sort the streams so the highest resolution is first. */
	std::sort(rawStreams.begin(), rawStreams.end(),
		  [](auto &l, auto &r) { return l.cfg->size > r.cfg->size; });

	std::sort(outStreams.begin(), outStreams.end(),
		  [](auto &l, auto &r) { return l.cfg->size > r.cfg->size; });

	/* Do any platform specific fixups. */
	status = data_->platformValidate(rawStreams, outStreams);
	if (status == Invalid)
		return Invalid;

	/* Further fixups on the RAW streams. */
	for (auto &raw : rawStreams) {
		StreamConfiguration &cfg = config_.at(raw.index);
		V4L2DeviceFormat rawFormat;

		const PixelFormatInfo &info = PixelFormatInfo::info(cfg.pixelFormat);
		unsigned int bitDepth = info.isValid() ? info.bitsPerPixel : defaultRawBitDepth;
		V4L2SubdeviceFormat sensorFormat = findBestFormat(data_->sensorFormats_, cfg.size, bitDepth);

		rawFormat.size = sensorFormat.size;
		rawFormat.fourcc = raw.dev->toV4L2PixelFormat(cfg.pixelFormat);

		int ret = raw.dev->tryFormat(&rawFormat);
		if (ret)
			return Invalid;
		/*
		 * Some sensors change their Bayer order when they are h-flipped
		 * or v-flipped, according to the transform. If this one does, we
		 * must advertise the transformed Bayer order in the raw stream.
		 * Note how we must fetch the "native" (i.e. untransformed) Bayer
		 * order, because the sensor may currently be flipped!
		 */
		V4L2PixelFormat fourcc = rawFormat.fourcc;
		if (data_->flipsAlterBayerOrder_) {
			BayerFormat bayer = BayerFormat::fromV4L2PixelFormat(fourcc);
			bayer.order = data_->nativeBayerOrder_;
			bayer = bayer.transform(combinedTransform_);
			fourcc = bayer.toV4L2PixelFormat();
		}

		PixelFormat inputPixFormat = fourcc.toPixelFormat();
		if (raw.cfg->size != rawFormat.size || raw.cfg->pixelFormat != inputPixFormat) {
			raw.cfg->size = rawFormat.size;
			raw.cfg->pixelFormat = inputPixFormat;
			status = Adjusted;
		}

		raw.cfg->stride = rawFormat.planes[0].bpl;
		raw.cfg->frameSize = rawFormat.planes[0].size;
	}

	/* Further fixups on the ISP output streams. */
	for (auto &out : outStreams) {
		StreamConfiguration &cfg = config_.at(out.index);
		PixelFormat &cfgPixFmt = cfg.pixelFormat;
		V4L2VideoDevice::Formats fmts = out.dev->formats();

		if (fmts.find(out.dev->toV4L2PixelFormat(cfgPixFmt)) == fmts.end()) {
			/* If we cannot find a native format, use a default one. */
			cfgPixFmt = formats::NV12;
			status = Adjusted;
		}

		V4L2DeviceFormat format;
		format.fourcc = out.dev->toV4L2PixelFormat(cfg.pixelFormat);
		format.size = cfg.size;
		/* We want to send the associated YCbCr info through to the driver. */
		format.colorSpace = yuvColorSpace_;

		LOG(RPI, Debug)
			<< "Try color space " << ColorSpace::toString(cfg.colorSpace);

		int ret = out.dev->tryFormat(&format);
		if (ret)
			return Invalid;

		/*
		 * But for RGB streams, the YCbCr info gets overwritten on the way back
		 * so we must check against what the stream cfg says, not what we actually
		 * requested (which carefully included the YCbCr info)!
		 */
		if (cfg.colorSpace != format.colorSpace) {
			status = Adjusted;
			LOG(RPI, Debug)
				<< "Color space changed from "
				<< ColorSpace::toString(cfg.colorSpace) << " to "
				<< ColorSpace::toString(format.colorSpace);
		}

		cfg.colorSpace = format.colorSpace;
		cfg.stride = format.planes[0].bpl;
		cfg.frameSize = format.planes[0].size;
	}

	return status;
}

V4L2DeviceFormat PipelineHandlerBase::toV4L2DeviceFormat(const V4L2VideoDevice *dev,
							 const V4L2SubdeviceFormat &format,
							 BayerFormat::Packing packingReq)
{
	unsigned int mbus_code = format.mbus_code;
	const PixelFormat pix = mbusCodeToPixelFormat(mbus_code, packingReq);
	V4L2DeviceFormat deviceFormat;

	deviceFormat.fourcc = dev->toV4L2PixelFormat(pix);
	deviceFormat.size = format.size;
	deviceFormat.colorSpace = format.colorSpace;
	return deviceFormat;
}

std::unique_ptr<CameraConfiguration>
PipelineHandlerBase::generateConfiguration(Camera *camera, const StreamRoles &roles)
{
	CameraData *data = cameraData(camera);
	std::unique_ptr<CameraConfiguration> config =
		std::make_unique<RPiCameraConfiguration>(data);
	V4L2SubdeviceFormat sensorFormat;
	unsigned int bufferCount;
	PixelFormat pixelFormat;
	V4L2VideoDevice::Formats fmts;
	Size size;
	std::optional<ColorSpace> colorSpace;

	if (roles.empty())
		return config;

	Size sensorSize = data->sensor_->resolution();
	for (const StreamRole role : roles) {
		switch (role) {
		case StreamRole::Raw:
			size = sensorSize;
			sensorFormat = findBestFormat(data->sensorFormats_, size, defaultRawBitDepth);
			pixelFormat = mbusCodeToPixelFormat(sensorFormat.mbus_code,
							    BayerFormat::Packing::CSI2);
			ASSERT(pixelFormat.isValid());
			colorSpace = ColorSpace::Raw;
			bufferCount = 2;
			break;

		case StreamRole::StillCapture:
			fmts = data->ispFormats();
			pixelFormat = formats::NV12;
			/*
			 * Still image codecs usually expect the sYCC color space.
			 * Even RGB codecs will be fine as the RGB we get with the
			 * sYCC color space is the same as sRGB.
			 */
			colorSpace = ColorSpace::Sycc;
			/* Return the largest sensor resolution. */
			size = sensorSize;
			bufferCount = 1;
			break;

		case StreamRole::VideoRecording:
			/*
			 * The colour denoise algorithm requires the analysis
			 * image, produced by the second ISP output, to be in
			 * YUV420 format. Select this format as the default, to
			 * maximize chances that it will be picked by
			 * applications and enable usage of the colour denoise
			 * algorithm.
			 */
			fmts = data->ispFormats();
			pixelFormat = formats::YUV420;
			/*
			 * Choose a color space appropriate for video recording.
			 * Rec.709 will be a good default for HD resolutions.
			 */
			colorSpace = ColorSpace::Rec709;
			size = { 1920, 1080 };
			bufferCount = 4;
			break;

		case StreamRole::Viewfinder:
			fmts = data->ispFormats();
			pixelFormat = formats::ARGB8888;
			colorSpace = ColorSpace::Sycc;
			size = { 800, 600 };
			bufferCount = 4;
			break;

		default:
			LOG(RPI, Error) << "Requested stream role not supported: "
					<< role;
			return nullptr;
		}

		std::map<PixelFormat, std::vector<SizeRange>> deviceFormats;
		if (role == StreamRole::Raw) {
			/* Translate the MBUS codes to a PixelFormat. */
			for (const auto &format : data->sensorFormats_) {
				PixelFormat pf = mbusCodeToPixelFormat(format.first,
								       BayerFormat::Packing::CSI2);
				if (pf.isValid())
					deviceFormats.emplace(std::piecewise_construct, std::forward_as_tuple(pf),
							      std::forward_as_tuple(format.second.begin(), format.second.end()));
			}
		} else {
			/*
			 * Translate the V4L2PixelFormat to PixelFormat. Note that we
			 * limit the recommended largest ISP output size to match the
			 * sensor resolution.
			 */
			for (const auto &format : fmts) {
				PixelFormat pf = format.first.toPixelFormat();
				if (pf.isValid()) {
					const SizeRange &ispSizes = format.second[0];
					deviceFormats[pf].emplace_back(ispSizes.min, sensorSize,
								       ispSizes.hStep, ispSizes.vStep);
				}
			}
		}

		/* Add the stream format based on the device node used for the use case. */
		StreamFormats formats(deviceFormats);
		StreamConfiguration cfg(formats);
		cfg.size = size;
		cfg.pixelFormat = pixelFormat;
		cfg.colorSpace = colorSpace;
		cfg.bufferCount = bufferCount;
		config->addConfiguration(cfg);
	}

	config->validate();

	return config;
}

int PipelineHandlerBase::configure(Camera *camera, CameraConfiguration *config)
{
	CameraData *data = cameraData(camera);
	int ret;

	/* Start by freeing all buffers and reset the stream states. */
	data->freeBuffers();
	for (auto const stream : data->streams_)
		stream->clearFlags(StreamFlag::External);

	std::vector<CameraData::StreamParams> rawStreams, ispStreams;
	std::optional<BayerFormat::Packing> packing;
	unsigned int bitDepth = defaultRawBitDepth;

	for (unsigned i = 0; i < config->size(); i++) {
		StreamConfiguration *cfg = &config->at(i);

		if (isRaw(cfg->pixelFormat))
			rawStreams.emplace_back(i, cfg);
		else
			ispStreams.emplace_back(i, cfg);
	}

	/* Sort the streams so the highest resolution is first. */
	std::sort(rawStreams.begin(), rawStreams.end(),
		  [](auto &l, auto &r) { return l.cfg->size > r.cfg->size; });

	std::sort(ispStreams.begin(), ispStreams.end(),
		  [](auto &l, auto &r) { return l.cfg->size > r.cfg->size; });

	/*
	 * Calculate the best sensor mode we can use based on the user's request,
	 * and apply it to the sensor with the cached tranform, if any.
	 *
	 * If we have been given a RAW stream, use that size for setting up the sensor.
	 */
	if (!rawStreams.empty()) {
		BayerFormat bayerFormat = BayerFormat::fromPixelFormat(rawStreams[0].cfg->pixelFormat);
		/* Replace the user requested packing/bit-depth. */
		packing = bayerFormat.packing;
		bitDepth = bayerFormat.bitDepth;
	}

	V4L2SubdeviceFormat sensorFormat = findBestFormat(data->sensorFormats_,
							  rawStreams.empty() ? ispStreams[0].cfg->size
									     : rawStreams[0].cfg->size,
							  bitDepth);
	/* Apply any cached transform. */
	const RPiCameraConfiguration *rpiConfig = static_cast<const RPiCameraConfiguration *>(config);

	/* Then apply the format on the sensor. */
	ret = data->sensor_->setFormat(&sensorFormat, rpiConfig->combinedTransform_);
	if (ret)
		return ret;

	/*
	 * Platform specific internal stream configuration. This also assigns
	 * external streams which get configured below.
	 */
	ret = data->platformConfigure(sensorFormat, packing, rawStreams, ispStreams);
	if (ret)
		return ret;

	ipa::RPi::ConfigResult result;
	ret = data->configureIPA(config, &result);
	if (ret) {
		LOG(RPI, Error) << "Failed to configure the IPA: " << ret;
		return ret;
	}

	/*
	 * Set the scaler crop to the value we are using (scaled to native sensor
	 * coordinates).
	 */
	data->scalerCrop_ = data->scaleIspCrop(data->ispCrop_);

	/*
	 * Update the ScalerCropMaximum to the correct value for this camera mode.
	 * For us, it's the same as the "analogue crop".
	 *
	 * \todo Make this property the ScalerCrop maximum value when dynamic
	 * controls are available and set it at validate() time
	 */
	data->properties_.set(properties::ScalerCropMaximum, data->sensorInfo_.analogCrop);

	/* Store the mode sensitivity for the application. */
	data->properties_.set(properties::SensorSensitivity, result.modeSensitivity);

	/* Update the controls that the Raspberry Pi IPA can handle. */
	ControlInfoMap::Map ctrlMap;
	for (auto const &c : result.controlInfo)
		ctrlMap.emplace(c.first, c.second);

	/* Add the ScalerCrop control limits based on the current mode. */
	Rectangle ispMinCrop = data->scaleIspCrop(Rectangle(data->ispMinCropSize_));
	ctrlMap[&controls::ScalerCrop] = ControlInfo(ispMinCrop, data->sensorInfo_.analogCrop, data->scalerCrop_);

	data->controlInfo_ = ControlInfoMap(std::move(ctrlMap), result.controlInfo.idmap());

	/* Setup the Video Mux/Bridge entities. */
	for (auto &[device, link] : data->bridgeDevices_) {
		/*
		 * Start by disabling all the sink pad links on the devices in the
		 * cascade, with the exception of the link connecting the device.
		 */
		for (const MediaPad *p : device->entity()->pads()) {
			if (!(p->flags() & MEDIA_PAD_FL_SINK))
				continue;

			for (MediaLink *l : p->links()) {
				if (l != link)
					l->setEnabled(false);
			}
		}

		/*
		 * Next, enable the entity -> entity links, and setup the pad format.
		 *
		 * \todo Some bridge devices may chainge the media bus code, so we
		 * ought to read the source pad format and propagate it to the sink pad.
		 */
		link->setEnabled(true);
		const MediaPad *sinkPad = link->sink();
		ret = device->setFormat(sinkPad->index(), &sensorFormat);
		if (ret) {
			LOG(RPI, Error) << "Failed to set format on " << device->entity()->name()
					<< " pad " << sinkPad->index()
					<< " with format  " << sensorFormat
					<< ": " << ret;
			return ret;
		}

		LOG(RPI, Debug) << "Configured media link on device " << device->entity()->name()
				<< " on pad " << sinkPad->index();
	}

	return 0;
}

int PipelineHandlerBase::exportFrameBuffers([[maybe_unused]] Camera *camera, libcamera::Stream *stream,
					    std::vector<std::unique_ptr<FrameBuffer>> *buffers)
{
	RPi::Stream *s = static_cast<RPi::Stream *>(stream);
	unsigned int count = stream->configuration().bufferCount;
	int ret = s->dev()->exportBuffers(count, buffers);

	s->setExportedBuffers(buffers);

	return ret;
}

int PipelineHandlerBase::start(Camera *camera, const ControlList *controls)
{
	CameraData *data = cameraData(camera);
	int ret;

	/* Check if a ScalerCrop control was specified. */
	if (controls)
		data->applyScalerCrop(*controls);

	/* Start the IPA. */
	ipa::RPi::StartResult result;
	data->ipa_->start(controls ? *controls : ControlList{ controls::controls },
			  &result);

	/* Apply any gain/exposure settings that the IPA may have passed back. */
	if (!result.controls.empty())
		data->setSensorControls(result.controls);

	/* Configure the number of dropped frames required on startup. */
	data->dropFrameCount_ = data->config_.disableStartupFrameDrops
			      ? 0 : result.dropFrameCount;

	for (auto const stream : data->streams_)
		stream->resetBuffers();

	if (!data->buffersAllocated_) {
		/* Allocate buffers for internal pipeline usage. */
		ret = prepareBuffers(camera);
		if (ret) {
			LOG(RPI, Error) << "Failed to allocate buffers";
			data->freeBuffers();
			stop(camera);
			return ret;
		}
		data->buffersAllocated_ = true;
	}

	/* We need to set the dropFrameCount_ before queueing buffers. */
	ret = queueAllBuffers(camera);
	if (ret) {
		LOG(RPI, Error) << "Failed to queue buffers";
		stop(camera);
		return ret;
	}

	/*
	 * Reset the delayed controls with the gain and exposure values set by
	 * the IPA.
	 */
	data->delayedCtrls_->reset(0);
	data->state_ = CameraData::State::Idle;

	/* Enable SOF event generation. */
	data->frontendDevice()->setFrameStartEnabled(true);

	data->platformStart();

	/* Start all streams. */
	for (auto const stream : data->streams_) {
		ret = stream->dev()->streamOn();
		if (ret) {
			stop(camera);
			return ret;
		}
	}

	return 0;
}

void PipelineHandlerBase::stopDevice(Camera *camera)
{
	CameraData *data = cameraData(camera);

	data->state_ = CameraData::State::Stopped;
	data->platformStop();

	for (auto const stream : data->streams_)
		stream->dev()->streamOff();

	/* Disable SOF event generation. */
	data->frontendDevice()->setFrameStartEnabled(false);

	data->clearIncompleteRequests();

	/* Stop the IPA. */
	data->ipa_->stop();
}

void PipelineHandlerBase::releaseDevice(Camera *camera)
{
	CameraData *data = cameraData(camera);
	data->freeBuffers();
}

int PipelineHandlerBase::queueRequestDevice(Camera *camera, Request *request)
{
	CameraData *data = cameraData(camera);

	if (!data->isRunning())
		return -EINVAL;

	LOG(RPI, Debug) << "queueRequestDevice: New request.";

	/* Push all buffers supplied in the Request to the respective streams. */
	for (auto stream : data->streams_) {
		if (!(stream->getFlags() & StreamFlag::External))
			continue;

		FrameBuffer *buffer = request->findBuffer(stream);
		if (buffer && !stream->getBufferId(buffer)) {
			/*
			 * This buffer is not recognised, so it must have been allocated
			 * outside the v4l2 device. Store it in the stream buffer list
			 * so we can track it.
			 */
			stream->setExternalBuffer(buffer);
		}

		/*
		 * If no buffer is provided by the request for this stream, we
		 * queue a nullptr to the stream to signify that it must use an
		 * internally allocated buffer for this capture request. This
		 * buffer will not be given back to the application, but is used
		 * to support the internal pipeline flow.
		 *
		 * The below queueBuffer() call will do nothing if there are not
		 * enough internal buffers allocated, but this will be handled by
		 * queuing the request for buffers in the RPiStream object.
		 */
		int ret = stream->queueBuffer(buffer);
		if (ret)
			return ret;
	}

	/* Push the request to the back of the queue. */
	data->requestQueue_.push(request);
	data->handleState();

	return 0;
}

int PipelineHandlerBase::registerCamera(std::unique_ptr<RPi::CameraData> &cameraData,
					MediaDevice *frontend, const std::string &frontendName,
					MediaDevice *backend, MediaEntity *sensorEntity)
{
	CameraData *data = cameraData.get();
	int ret;

	data->sensor_ = std::make_unique<CameraSensor>(sensorEntity);
	if (!data->sensor_)
		return -EINVAL;

	if (data->sensor_->init())
		return -EINVAL;

	data->sensorFormats_ = populateSensorFormats(data->sensor_);

	/*
	 * Enumerate all the Video Mux/Bridge devices across the sensor -> Fr
	 * chain. There may be a cascade of devices in this chain!
	 */
	MediaLink *link = sensorEntity->getPadByIndex(0)->links()[0];
	data->enumerateVideoDevices(link, frontendName);

	ipa::RPi::InitResult result;
	if (data->loadIPA(&result)) {
		LOG(RPI, Error) << "Failed to load a suitable IPA library";
		return -EINVAL;
	}

	/*
	 * Setup our delayed control writer with the sensor default
	 * gain and exposure delays. Mark VBLANK for priority write.
	 */
	std::unordered_map<uint32_t, RPi::DelayedControls::ControlParams> params = {
		{ V4L2_CID_ANALOGUE_GAIN, { result.sensorConfig.gainDelay, false } },
		{ V4L2_CID_EXPOSURE, { result.sensorConfig.exposureDelay, false } },
		{ V4L2_CID_HBLANK, { result.sensorConfig.hblankDelay, false } },
		{ V4L2_CID_VBLANK, { result.sensorConfig.vblankDelay, true } }
	};
	data->delayedCtrls_ = std::make_unique<RPi::DelayedControls>(data->sensor_->device(), params);
	data->sensorMetadata_ = result.sensorConfig.sensorMetadata;

	/* Register initial controls that the Raspberry Pi IPA can handle. */
	data->controlInfo_ = std::move(result.controlInfo);

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

	/*
	 * The V4L2_CID_NOTIFY_GAINS control, if present, is used to inform the
	 * sensor of the colour gains. It is defined to be a linear gain where
	 * the default value represents a gain of exactly one.
	 */
	auto it = data->sensor_->controls().find(V4L2_CID_NOTIFY_GAINS);
	if (it != data->sensor_->controls().end())
		data->notifyGainsUnity_ = it->second.def().get<int32_t>();

	/*
	 * Set a default value for the ScalerCropMaximum property to show
	 * that we support its use, however, initialise it to zero because
	 * it's not meaningful until a camera mode has been chosen.
	 */
	data->properties_.set(properties::ScalerCropMaximum, Rectangle{});

	/*
	 * We cache two things about the sensor in relation to transforms
	 * (meaning horizontal and vertical flips): if they affect the Bayer
	 * ordering, and what the "native" Bayer order is, when no transforms
	 * are applied.
	 *
	 * If flips are supported verify if they affect the Bayer ordering
	 * and what the "native" Bayer order is, when no transforms are
	 * applied.
	 *
	 * We note that the sensor's cached list of supported formats is
	 * already in the "native" order, with any flips having been undone.
	 */
	const V4L2Subdevice *sensor = data->sensor_->device();
	const struct v4l2_query_ext_ctrl *hflipCtrl = sensor->controlInfo(V4L2_CID_HFLIP);
	if (hflipCtrl) {
		/* We assume it will support vflips too... */
		data->flipsAlterBayerOrder_ = hflipCtrl->flags & V4L2_CTRL_FLAG_MODIFY_LAYOUT;
	}

	/* Look for a valid Bayer format. */
	BayerFormat bayerFormat;
	for (const auto &iter : data->sensorFormats_) {
		bayerFormat = BayerFormat::fromMbusCode(iter.first);
		if (bayerFormat.isValid())
			break;
	}

	if (!bayerFormat.isValid()) {
		LOG(RPI, Error) << "No Bayer format found";
		return -EINVAL;
	}
	data->nativeBayerOrder_ = bayerFormat.order;

	ret = platformRegister(cameraData, frontend, backend);
	if (ret)
		return ret;