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2024-05-08libcamera: Drop file name from header comment blocksLaurent Pinchart
Source files in libcamera start by a comment block header, which includes the file name and a one-line description of the file contents. While the latter is useful to get a quick overview of the file contents at a glance, the former is mostly a source of inconvenience. The name in the comments can easily get out of sync with the file name when files are renamed, and copy & paste during development have often lead to incorrect names being used to start with. Readers of the source code are expected to know which file they're looking it. Drop the file name from the header comment block. The change was generated with the following script: ---------------------------------------- dirs="include/libcamera src test utils" declare -rA patterns=( ['c']=' \* ' ['cpp']=' \* ' ['h']=' \* ' ['py']='# ' ['sh']='# ' ) for ext in ${!patterns[@]} ; do files=$(for dir in $dirs ; do find $dir -name "*.${ext}" ; done) pattern=${patterns[${ext}]} for file in $files ; do name=$(basename ${file}) sed -i "s/^\(${pattern}\)${name} - /\1/" "$file" done done ---------------------------------------- This misses several files that are out of sync with the comment block header. Those will be addressed separately and manually. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Daniel Scally <dan.scally@ideasonboard.com>
2024-01-25test: message: Destroy Object from correct thread contextLaurent Pinchart
The MessageReceiver and RecursiveMessageReceiver used in the test are destroyed from the main thread, which is invalid for a thread-bound object bound to a different thread. Fix it by destroying them with deleteLater(). Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Milan Zamazal <mzamazal@redhat.com>
2024-01-25test: message: Remove incorrect slow receiver testLaurent Pinchart
The slow receiver test verifies there's no race condition between concurrent message delivery and object deletion. This is not a valid use case in the first place, as objects are not allowed to be deleted from a different thread than the one they are bound to. Remove the incorrect test. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Milan Zamazal <mzamazal@redhat.com>
2024-01-25libcamera: signal: Replace object.h inclusion with forward declatationLaurent Pinchart
The signal.h header doesn't need to include object.h. Replace it with a forward declaration, and instead include object.h in source files that require it. It can speed up compilation a little bit, but more importantly avoids unintended dependencies from the Signal class to the Object class to be added later as the compiler will catch them. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Milan Zamazal <mzamazal@redhat.com>
2021-07-11test: message: Test recursive Thread::dispatchMessages() callsLaurent Pinchart
The Thread::dispatchMessages() function needs to support recursive calls, for instance to allow flushing delivery of invoked methods. Add a corresponding test, which currently fails with a double free. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Jacopo Mondi <jacopo@jmondi.org> Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
2021-06-25libcamera/base: Move extended base functionalityKieran Bingham
Move the functionality for the following components to the new base support library: - BoundMethod - EventDispatcher - EventDispatcherPoll - Log - Message - Object - Signal - Semaphore - Thread - Timer While it would be preferable to see these split to move one component per commit, these components are all interdependent upon each other, which leaves us with one big change performing the move for all of them. Reviewed-by: Hirokazu Honda <hiroh@chromium.org> Reviewed-by: Paul Elder <paul.elder@ideasonboard.com> Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
2020-05-16libcamera: Move internal headers to include/libcamera/internal/Laurent Pinchart
The libcamera internal headers are located in src/libcamera/include/. The directory is added to the compiler headers search path with a meson include_directories() directive, and internal headers are included with (e.g. for the internal semaphore.h header) #include "semaphore.h" All was well, until libcxx decided to implement the C++20 synchronization library. The __threading_support header gained a #include <semaphore.h> to include the pthread's semaphore support. As include_directories() adds src/libcamera/include/ to the compiler search path with -I, the internal semaphore.h is included instead of the pthread version. Needless to say, the compiler isn't happy. Three options have been considered to fix this issue: - Use -iquote instead of -I. The -iquote option instructs gcc to only consider the header search path for headers included with the "" version. Meson unfortunately doesn't support this option. - Rename the internal semaphore.h header. This was deemed to be the beginning of a long whack-a-mole game, where namespace clashes with system libraries would appear over time (possibly dependent on particular system configurations) and would need to be constantly fixed. - Move the internal headers to another directory to create a unique namespace through path components. This causes lots of churn in all the existing source files through the all project. The first option would be best, but isn't available to us due to missing support in meson. Even if -iquote support was added, we would need to fix the problem before a new version of meson containing the required support would be released. The third option is thus the only practical solution available. Bite the bullet, and do it, moving headers to include/libcamera/internal/. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Acked-by: Jacopo Mondi <jacopo@jmondi.org>
2020-01-14libcamera: Switch from utils::make_unique to std::make_uniqueLaurent Pinchart
Now that we're using C++-14, drop utils::make_unique for std::make_unique. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com> Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
2019-11-27test: message: Add slow receiver testLaurent Pinchart
There's a race in the message delivery against object deletion. Add a test that triggers it reliably. This test is expected to fail with an assertion error. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Jacopo Mondi <jacopo@jmondi.org> Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
2019-11-27test: message: Fix message handling in MessageReceiverLaurent Pinchart
Forward messages that we don't handle to the base Object class, to avoid both blocking the ThreadMove message and mistaking it as the test message. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Jacopo Mondi <jacopo@jmondi.org> Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
2019-07-16libcamera: message: Add user message typesJacopo Mondi
Reserve identifiers for user-defined message types and add an operation to the Message class to register the type identifiers. Signed-off-by: Jacopo Mondi <jacopo@jmondi.org> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
2019-07-11test: Add Message test caseLaurent Pinchart
The Message class test creates a receiver inheriting from Object, moves it to a different thread, sends a message to the receiver and verifies that the message is delivered in the correct thread. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
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/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
 * Copyright (C) 2019, Google Inc.
 *
 * v4l2_device.cpp - Common base for V4L2 video devices and subdevices
 */

#include "libcamera/internal/v4l2_device.h"

#include <fcntl.h>
#include <iomanip>
#include <limits.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/syscall.h>
#include <unistd.h>

#include "libcamera/internal/event_notifier.h"
#include "libcamera/internal/log.h"
#include "libcamera/internal/sysfs.h"
#include "libcamera/internal/utils.h"
#include "libcamera/internal/v4l2_controls.h"

/**
 * \file v4l2_device.h
 * \brief Common base for V4L2 devices and subdevices
 */

namespace libcamera {

LOG_DEFINE_CATEGORY(V4L2)

/**
 * \class V4L2Device
 * \brief Base class for V4L2VideoDevice and V4L2Subdevice
 *
 * The V4L2Device class groups together the methods and fields common to
 * both the V4L2VideoDevice and V4L2Subdevice classes, and provides a base
 * class with methods to open and close the device node associated with the
 * device and to perform IOCTL system calls on it.
 *
 * The V4L2Device class cannot be instantiated directly, as its constructor
 * is protected. Users should instead create instances of one the derived
 * classes to model either a V4L2 video device or a V4L2 subdevice.
 */

/**
 * \brief Construct a V4L2Device
 * \param[in] deviceNode The device node filesystem path
 *
 * Initialize the file descriptor to -1 and store the \a deviceNode to be used
 * at open() time, and the \a logTag to prefix log messages with.
 */
V4L2Device::V4L2Device(const std::string &deviceNode)
	: deviceNode_(deviceNode), fd_(-1), fdEventNotifier_(nullptr),
	  frameStartEnabled_(false)
{
}

/**
 * \brief Destroy a V4L2Device
 */
V4L2Device::~V4L2Device()
{
}

/**
 * \brief Open a V4L2 device node
 * \param[in] flags Access mode flags
 *
 * Open the device node path with the provided access mode \a flags and
 * initialize the file descriptor, which was initially set to -1.
 *
 * \return 0 on success or a negative error code otherwise
 */
int V4L2Device::open(unsigned int flags)
{
	if (isOpen()) {
		LOG(V4L2, Error) << "Device already open";
		return -EBUSY;
	}

	int ret = syscall(SYS_openat, AT_FDCWD, deviceNode_.c_str(), flags);
	if (ret < 0) {
		ret = -errno;
		LOG(V4L2, Error) << "Failed to open V4L2 device: "
				 << strerror(-ret);
		return ret;
	}

	setFd(ret);

	listControls();

	return 0;
}

/**
 * \brief Set the file descriptor of a V4L2 device
 * \param[in] fd The file descriptor handle
 *
 * This method allows a device to provide an already opened file descriptor
 * referring to the V4L2 device node, instead of opening it with open(). This
 * can be used for V4L2 M2M devices where a single video device node is used for
 * both the output and capture devices, or when receiving an open file
 * descriptor in a context that doesn't have permission to open the device node
 * itself.
 *
 * This method and the open() method are mutually exclusive, only one of the two
 * shall be used for a V4L2Device instance.
 *
 * \return 0 on success or a negative error code otherwise
 */
int V4L2Device::setFd(int fd)
{
	if (isOpen())
		return -EBUSY;

	fd_ = fd;

	fdEventNotifier_ = new EventNotifier(fd_, EventNotifier::Exception);
	fdEventNotifier_->activated.connect(this, &V4L2Device::eventAvailable);
	fdEventNotifier_->setEnabled(false);

	return 0;
}

/**
 * \brief Close the device node
 *
 * Reset the file descriptor to -1
 */
void V4L2Device::close()
{
	if (!isOpen())
		return;

	delete fdEventNotifier_;

	if (::close(fd_) < 0)
		LOG(V4L2, Error) << "Failed to close V4L2 device: "
				 << strerror(errno);
	fd_ = -1;
}

/**
 * \fn V4L2Device::isOpen()
 * \brief Check if the V4L2 device node is open
 * \return True if the V4L2 device node is open, false otherwise
 */

/**
 * \fn V4L2Device::controls()
 * \brief Retrieve the supported V4L2 controls and their information
 * \return A map of the V4L2 controls supported by the device
 */

/**
 * \brief Read controls from the device
 * \param[in] ids The list of controls to read, specified by their ID
 *
 * This method reads the value of all controls contained in \a ids, and returns
 * their values as a ControlList.
 *
 * If any control in \a ids is not supported by the device, is disabled (i.e.
 * has the V4L2_CTRL_FLAG_DISABLED flag set), or if any other error occurs
 * during validation of the requested controls, no control is read and this
 * method returns an empty control list.
 *
 * \return The control values in a ControlList on success, or an empty list on
 * error
 */
ControlList V4L2Device::getControls(const std::vector<uint32_t> &ids)
{
	if (ids.empty())
		return {};

	ControlList ctrls{ controls_ };

	/*
	 * Start by filling the ControlList. This can't be combined with filling
	 * v4l2Ctrls, as updateControls() relies on both containers having the
	 * same order, and the control list is based on a map, which is not
	 * sorted by insertion order.
	 */
	for (uint32_t id : ids) {
		const auto iter = controls_.find(id);
		if (iter == controls_.end()) {
			LOG(V4L2, Error)
				<< "Control " << utils::hex(id) << " not found";
			return {};
		}

		ctrls.set(id, {});
	}

	std::vector<v4l2_ext_control> v4l2Ctrls(ids.size());
	memset(v4l2Ctrls.data(), 0, sizeof(v4l2_ext_control) * ctrls.size());

	unsigned int i = 0;
	for (auto &ctrl : ctrls) {
		unsigned int id = ctrl.first;
		const struct v4l2_query_ext_ctrl &info = controlInfo_[id];

		v4l2_ext_control &v4l2Ctrl = v4l2Ctrls[i++];
		v4l2Ctrl.id = id;

		if (info.flags & V4L2_CTRL_FLAG_HAS_PAYLOAD) {
			ControlType type;

			switch (info.type) {
			case V4L2_CTRL_TYPE_U8:
				type = ControlTypeByte;
				break;

			default:
				LOG(V4L2, Error)
					<< "Unsupported payload control type "
					<< info.type;
				return {};
			}

			ControlValue &value = ctrl.second;
			value.reserve(type, true, info.elems);
			Span<uint8_t> data = value.data();

			v4l2Ctrl.p_u8 = data.data();
			v4l2Ctrl.size = data.size();
		}
	}

	struct v4l2_ext_controls v4l2ExtCtrls = {};
	v4l2ExtCtrls.which = V4L2_CTRL_WHICH_CUR_VAL;
	v4l2ExtCtrls.controls = v4l2Ctrls.data();
	v4l2ExtCtrls.count = v4l2Ctrls.size();

	int ret = ioctl(VIDIOC_G_EXT_CTRLS, &v4l2ExtCtrls);
	if (ret) {
		unsigned int errorIdx = v4l2ExtCtrls.error_idx;

		/* Generic validation error. */
		if (errorIdx == 0 || errorIdx >= v4l2Ctrls.size()) {
			LOG(V4L2, Error) << "Unable to read controls: "
					 << strerror(-ret);
			return {};
		}

		/* A specific control failed. */
		LOG(V4L2, Error) << "Unable to read control " << errorIdx
				 << ": " << strerror(-ret);

		v4l2Ctrls.resize(errorIdx);
	}

	updateControls(&ctrls, v4l2Ctrls);

	return ctrls;
}

/**
 * \brief Write controls to the device
 * \param[in] ctrls The list of controls to write
 *
 * This method writes the value of all controls contained in \a ctrls, and
 * stores the values actually applied to the device in the corresponding
 * \a ctrls entry.
 *
 * If any control in \a ctrls is not supported by the device, is disabled (i.e.
 * has the V4L2_CTRL_FLAG_DISABLED flag set), is read-only, if any other error
 * occurs during validation of the requested controls, no control is written and
 * this method returns -EINVAL.
 *
 * If an error occurs while writing the controls, the index of the first
 * control that couldn't be written is returned. All controls below that index
 * are written and their values are updated in \a ctrls, while all other
 * controls are not written and their values are not changed.
 *
 * \return 0 on success or an error code otherwise
 * \retval -EINVAL One of the control is not supported or not accessible
 * \retval i The index of the control that failed
 */
int V4L2Device::setControls(ControlList *ctrls)
{
	if (ctrls->empty())
		return 0;

	std::vector<v4l2_ext_control> v4l2Ctrls(ctrls->size());
	memset(v4l2Ctrls.data(), 0, sizeof(v4l2_ext_control) * ctrls->size());

	for (auto [ctrl, i] = std::pair(ctrls->begin(), 0u); i < ctrls->size(); ctrl++, i++) {
		const unsigned int id = ctrl->first;
		const auto iter = controls_.find(id);
		if (iter == controls_.end()) {
			LOG(V4L2, Error)
				<< "Control " << utils::hex(id) << " not found";
			return -EINVAL;
		}
		v4l2_ext_control &v4l2Ctrl = v4l2Ctrls[i];
		v4l2Ctrl.id = id;

		/* Set the v4l2_ext_control value for the write operation. */
		ControlValue &value = ctrl->second;
		switch (iter->first->type()) {
		case ControlTypeInteger64:
			v4l2Ctrl.value64 = value.get<int64_t>();
			break;

		case ControlTypeByte: {
			if (!value.isArray()) {
				LOG(V4L2, Error)
					<< "Control " << utils::hex(id)
					<< " requires an array value";
				return -EINVAL;
			}

			Span<uint8_t> data = value.data();
			v4l2Ctrl.p_u8 = data.data();
			v4l2Ctrl.size = data.size();

			break;
		}

		default:
			/* \todo To be changed to support strings. */
			v4l2Ctrl.value = value.get<int32_t>();
			break;
		}
	}

	struct v4l2_ext_controls v4l2ExtCtrls = {};
	v4l2ExtCtrls.which = V4L2_CTRL_WHICH_CUR_VAL;
	v4l2ExtCtrls.controls = v4l2Ctrls.data();
	v4l2ExtCtrls.count = v4l2Ctrls.size();

	int ret = ioctl(VIDIOC_S_EXT_CTRLS, &v4l2ExtCtrls);
	if (ret) {
		unsigned int errorIdx = v4l2ExtCtrls.error_idx;

		/* Generic validation error. */
		if (errorIdx == 0 || errorIdx >= v4l2Ctrls.size()) {
			LOG(V4L2, Error) << "Unable to set controls: "
					 << strerror(-ret);
			return -EINVAL;
		}

		/* A specific control failed. */
		LOG(V4L2, Error) << "Unable to set control " << errorIdx
				 << ": " << strerror(-ret);

		v4l2Ctrls.resize(errorIdx);
		ret = errorIdx;
	}

	updateControls(ctrls, v4l2Ctrls);

	return ret;
}

/**
 * \brief Retrieve the v4l2_query_ext_ctrl information for the given control
 * \param[in] id The V4L2 control id
 * \return A pointer to the v4l2_query_ext_ctrl structure for the given
 * control, or a null pointer if not found
 */
const struct v4l2_query_ext_ctrl *V4L2Device::controlInfo(uint32_t id) const
{
	const auto it = controlInfo_.find(id);
	if (it == controlInfo_.end())
		return nullptr;

	return &it->second;
}

/**
 * \brief Retrieve the device path in sysfs
 *
 * This function returns the sysfs path to the physical device backing the V4L2
 * device. The path is guaranteed to be an absolute path, without any symbolic
 * link.
 *
 * It includes the sysfs mount point prefix
 *
 * \return The device path in sysfs
 */
std::string V4L2Device::devicePath() const
{
	std::string devicePath = sysfs::charDevPath(deviceNode_) + "/device";

	char *realPath = realpath(devicePath.c_str(), nullptr);
	if (!realPath) {
		LOG(V4L2, Fatal)
			<< "Can not resolve device path for " << devicePath;
		return {};
	}

	std::string path{ realPath };
	free(realPath);

	return path;
}

/**
 * \brief Enable or disable frame start event notification
 * \param[in] enable True to enable frame start events, false to disable them
 *
 * This function enables or disables generation of frame start events. Once
 * enabled, the events are signalled through the frameStart signal.
 *
 * \return 0 on success, a negative error code otherwise
 */
int V4L2Device::setFrameStartEnabled(bool enable)
{
	if (frameStartEnabled_ == enable)
		return 0;

	struct v4l2_event_subscription event{};
	event.type = V4L2_EVENT_FRAME_SYNC;

	unsigned long request = enable ? VIDIOC_SUBSCRIBE_EVENT
			      : VIDIOC_UNSUBSCRIBE_EVENT;
	int ret = ioctl(request, &event);
	if (enable && ret)
		return ret;

	fdEventNotifier_->setEnabled(enable);
	frameStartEnabled_ = enable;

	return ret;
}

/**
 * \var V4L2Device::frameStart
 * \brief A Signal emitted when capture of a frame has started
 */

/**
 * \brief Perform an IOCTL system call on the device node
 * \param[in] request The IOCTL request code
 * \param[in] argp A pointer to the IOCTL argument
 * \return 0 on success or a negative error code otherwise
 */
int V4L2Device::ioctl(unsigned long request, void *argp)
{
	/*
	 * Printing out an error message is usually better performed
	 * in the caller, which can provide more context.
	 */
	if (::ioctl(fd_, request, argp) < 0)
		return -errno;

	return 0;
}

/**
 * \fn V4L2Device::deviceNode()
 * \brief Retrieve the device node path
 * \return The device node path
 */

/**
 * \fn V4L2Device::fd()
 * \brief Retrieve the V4L2 device file descriptor
 * \return The V4L2 device file descriptor, -1 if the device node is not open
 */

/*
 * \brief List and store information about all controls supported by the
 * V4L2 device
 */
void V4L2Device::listControls()
{
	ControlInfoMap::Map ctrls;
	struct v4l2_query_ext_ctrl ctrl = {};

	/* \todo Add support for menu controls. */
	while (1) {
		ctrl.id |= V4L2_CTRL_FLAG_NEXT_CTRL |
			   V4L2_CTRL_FLAG_NEXT_COMPOUND;
		if (ioctl(VIDIOC_QUERY_EXT_CTRL, &ctrl))
			break;

		if (ctrl.type == V4L2_CTRL_TYPE_CTRL_CLASS ||
		    ctrl.flags & V4L2_CTRL_FLAG_DISABLED)
			continue;

		switch (ctrl.type) {
		case V4L2_CTRL_TYPE_INTEGER:
		case V4L2_CTRL_TYPE_BOOLEAN:
		case V4L2_CTRL_TYPE_MENU:
		case V4L2_CTRL_TYPE_BUTTON:
		case V4L2_CTRL_TYPE_INTEGER64:
		case V4L2_CTRL_TYPE_BITMASK:
		case V4L2_CTRL_TYPE_INTEGER_MENU:
		case V4L2_CTRL_TYPE_U8:
			break;
		/* \todo Support other control types. */
		default:
			LOG(V4L2, Debug)
				<< "Control " << utils::hex(ctrl.id)
				<< " has unsupported type " << ctrl.type;
			continue;
		}

		controlIds_.emplace_back(std::make_unique<V4L2ControlId>(ctrl));
		controlInfo_.emplace(ctrl.id, ctrl);

		ctrls.emplace(controlIds_.back().get(), V4L2ControlInfo(ctrl));
	}

	controls_ = std::move(ctrls);
}

/**
* \brief Update the information for all device controls
 *
 * The V4L2Device class caches information about all controls supported by the
 * device and exposes it through the controls() and controlInfo() functions.
 * Control information may change at runtime, for instance when formats on a
 * subdev are modified. When this occurs, this function can be used to refresh
 * control information. The information is refreshed in-place, all pointers to
 * v4l2_query_ext_ctrl instances previously returned by controlInfo() and
 * iterators to the ControlInfoMap returned by controls() remain valid.
 *
 * Note that control information isn't refreshed automatically is it may be an
 * expensive operation. The V4L2Device users are responsible for calling this
 * function when required, based on their usage pattern of the class.
 */
void V4L2Device::updateControlInfo()
{
	for (auto &[controlId, info] : controls_) {
		unsigned int id = controlId->id();

		/*
		 * Assume controlInfo_ has a corresponding entry, as it has been
		 * generated by listControls().
		 */
		struct v4l2_query_ext_ctrl &ctrl = controlInfo_[id];

		if (ioctl(VIDIOC_QUERY_EXT_CTRL, &ctrl)) {
			LOG(V4L2, Debug)
				<< "Could not refresh control "
				<< utils::hex(id);
			continue;
		}

		info = V4L2ControlInfo(ctrl);
	}
}

/*
 * \brief Update the value of the first \a count V4L2 controls in \a ctrls using
 * values in \a v4l2Ctrls
 * \param[inout] ctrls List of V4L2 controls to update
 * \param[in] v4l2Ctrls List of V4L2 extended controls as returned by the driver
 */
void V4L2Device::updateControls(ControlList *ctrls,
				Span<const v4l2_ext_control> v4l2Ctrls)
{
	unsigned int i = 0;
	for (auto &ctrl : *ctrls) {
		if (i == v4l2Ctrls.size())
			break;

		const struct v4l2_ext_control *v4l2Ctrl = &v4l2Ctrls[i];
		unsigned int id = ctrl.first;
		ControlValue &value = ctrl.second;

		const auto iter = controls_.find(id);
		switch (iter->first->type()) {
		case ControlTypeInteger64:
			value.set<int64_t>(v4l2Ctrl->value64);
			break;

		case ControlTypeByte:
			/*
			 * No action required, the VIDIOC_[GS]_EXT_CTRLS ioctl
			 * accessed the ControlValue storage directly.
			 */
			break;

		default:
			/*
			 * \todo To be changed when support for string controls
			 * will be added.
			 */
			value.set<int32_t>(v4l2Ctrl->value);
			break;
		}

		i++;
	}
}

/**
 * \brief Slot to handle V4L2 events from the V4L2 device
 * \param[in] notifier The event notifier
 *
 * When this slot is called, a V4L2 event is available to be dequeued from the
 * device.
 */
void V4L2Device::eventAvailable([[maybe_unused]] EventNotifier *notifier)
{
	struct v4l2_event event{};
	int ret = ioctl(VIDIOC_DQEVENT, &event);
	if (ret < 0) {
		LOG(V4L2, Error)
			<< "Failed to dequeue event, disabling event notifier";
		fdEventNotifier_->setEnabled(false);
		return;
	}

	if (event.type != V4L2_EVENT_FRAME_SYNC) {
		LOG(V4L2, Error)
			<< "Spurious event (" << event.type
			<< "), disabling event notifier";
		fdEventNotifier_->setEnabled(false);
		return;
	}

	frameStart.emit(event.u.frame_sync.frame_sequence);
}

} /* namespace libcamera */