[libcamera-devel] [PATCH v5 1/3] libcamera: Introduce camera sensor database

[Laurent Pinchart]

Hi Jacopo,

Thank you for the patch.

On Tue, Apr 13, 2021 at 12:14:37PM +0200, Jacopo Mondi wrote:
> Introduce a 'database' of camera sensor information, which contains
> the camera sensor properties which are not possible, or desirable,
> to retrieve at run time.
> 
> The camera sensor database is accessed through the static SensorDatabase
> class which provides a single method to obtain the sensor properties.

It's not the class that is static, but the function.

> Reviewed-by: Hirokazu Honda <hiroh at chromium.org>
> Reviewed-by: Niklas Söderlund <niklas.soderlund at ragnatech.se>
> Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>
> ---
>  include/libcamera/internal/meson.build       |  1 +
>  include/libcamera/internal/sensor_database.h | 28 ++++++
>  src/libcamera/meson.build                    |  1 +
>  src/libcamera/sensor_database.cpp            | 94 ++++++++++++++++++++
>  4 files changed, 124 insertions(+)
>  create mode 100644 include/libcamera/internal/sensor_database.h
>  create mode 100644 src/libcamera/sensor_database.cpp
> 
> diff --git a/include/libcamera/internal/meson.build b/include/libcamera/internal/meson.build
> index 1fe3918cfe93..4aaa76ac1db1 100644
> --- a/include/libcamera/internal/meson.build
> +++ b/include/libcamera/internal/meson.build
> @@ -38,6 +38,7 @@ libcamera_internal_headers = files([
>      'process.h',
>      'pub_key.h',
>      'semaphore.h',
> +    'sensor_database.h',
>      'sysfs.h',
>      'thread.h',
>      'timer.h',
> diff --git a/include/libcamera/internal/sensor_database.h b/include/libcamera/internal/sensor_database.h
> new file mode 100644
> index 000000000000..5f58b17a7b1d
> --- /dev/null
> +++ b/include/libcamera/internal/sensor_database.h
> @@ -0,0 +1,28 @@
> +/* SPDX-License-Identifier: LGPL-2.1-or-later */
> +/*
> + * Copyright (C) 2021, Google Inc.
> + *
> + * sensor_database.h - Database of camera sensor properties
> + */
> +#ifndef __LIBCAMERA_SENSOR_DATABASE_H__
> +#define __LIBCAMERA_SENSOR_DATABASE_H__
> +
> +#include <string>
> +
> +#include <libcamera/geometry.h>
> +
> +namespace libcamera {
> +
> +struct CameraSensorProperties {
> +	Size unitCellSize;
> +};
> +
> +class SensorDatabase
> +{
> +public:
> +	static const CameraSensorProperties *get(const std::string &sensor);
> +};

Do we need this class ? It would seem simpler to me to move this
function to the CameraSensorProperties class. It's not big deal though,
but if you keep the class, I'd name it CameraSensorDatabase for
consistency.

> +
> +} /* namespace libcamera */
> +
> +#endif /* __LIBCAMERA_SENSOR_DATABASE_H__ */
> diff --git a/src/libcamera/meson.build b/src/libcamera/meson.build
> index e0a48aa23ea5..effae0ef5186 100644
> --- a/src/libcamera/meson.build
> +++ b/src/libcamera/meson.build
> @@ -44,6 +44,7 @@ libcamera_sources = files([
>      'pub_key.cpp',
>      'request.cpp',
>      'semaphore.cpp',
> +    'sensor_database.cpp',
>      'signal.cpp',
>      'stream.cpp',
>      'sysfs.cpp',
> diff --git a/src/libcamera/sensor_database.cpp b/src/libcamera/sensor_database.cpp
> new file mode 100644
> index 000000000000..d6a97e06adfc
> --- /dev/null
> +++ b/src/libcamera/sensor_database.cpp
> @@ -0,0 +1,94 @@
> +/* SPDX-License-Identifier: LGPL-2.1-or-later */
> +/*
> + * Copyright (C) 2021, Google Inc.
> + *
> + * sensor_database.cpp - Database of camera sensor properties
> + */
> +
> +#include "libcamera/internal/sensor_database.h"
> +
> +#include <map>
> +
> +#include "libcamera/internal/log.h"
> +
> +/**
> + * \file sensor_database.h
> + * \brief Database of camera sensor properties
> + *
> + * The camera sensor database collects static information about camera sensors
> + * that is not possible or desirable to retrieve at run time.

Should we say "to retrieve from the device", as, from the point of view
of a user of this class, calling get() is a runtime operation ?

> + */
> +
> +namespace libcamera {
> +
> +LOG_DEFINE_CATEGORY(SensorDatabase)
> +
> +/**
> + * \struct CameraSensorProperties
> + * \brief List of sensor properties
> + *
> + * \var CameraSensorProperties::unitCellSize
> + * \brief The physical size of a pixel, including pixel edges, in nanometers.
> + */
> +
> +/**
> + * \class SensorDatabase
> + * \brief Access the database of camera sensor properties
> + *
> + * The database is indexed using the camera sensor model, as reported by the
> + * properties::Model property, and for each supported sensor it contains a
> + * CameraSensorProperties list of properties.
> + *
> + * The class provides a single static get() method to access the sensor database
> + * entries. If the sensor is not supported in the database nullptr is returned.

You can drop the last sentence, that's documented below already.

> + */
> +
> +namespace {
> +
> +/** \brief Sony IMX219 sensor properties */
> +constexpr CameraSensorProperties imx219Props = {
> +	.unitCellSize = { 1120, 1120 }
> +};
> +
> +/** \brief Omnivision ov5670 sensor properties */
> +constexpr CameraSensorProperties ov5670Props = {
> +	.unitCellSize = { 1120, 1120 }
> +};
> +
> +/** \brief Omnivision 13858 sensor properties */
> +constexpr CameraSensorProperties ov13858Props = {
> +	.unitCellSize = { 1120, 1120 }
> +};
> +
> +#define SENSOR_PROPERTIES(_sensor) \
> +	{ #_sensor, &_sensor##Props }
> +
> +} /* namespace */
> +
> +/**
> + * \brief Retrieve the properties associated with a sensor
> + * \param sensor The sensor model name
> + * \return A pointer to the CameraSensorProperties instance associated with a sensor
> + * or nullptr if the sensor is not supported in the database
> + */
> +const CameraSensorProperties *SensorDatabase::get(const std::string &sensor)
> +{
> +	static const std::map<std::string, const CameraSensorProperties *> sensorDatabase = {
> +		SENSOR_PROPERTIES(imx219),
> +		SENSOR_PROPERTIES(ov5670),
> +		SENSOR_PROPERTIES(ov13858),
> +	};

I don't really see what the constexpr data above brings us, expect a
macro that obfuscates the code a bit. Isn't this better ?

	static const std::map<std::string, const CameraSensorProperties *> sensorDatabase = {
		{ "imx219", {
			.unitCellSize = { 1120, 1120 },
		} },
		{ "ov5670", {
			.unitCellSize = { 1120, 1120 },
		} },
		{ "ov13858", {
			.unitCellSize = { 1120, 1120 },
		} },
	};

> +
> +	const auto it = sensorDatabase.find(sensor);
> +	if (it == sensorDatabase.end()) {
> +		LOG(SensorDatabase, Warning)
> +			<< "No static properties available for '" << sensor << "'";
> +		LOG(SensorDatabase, Warning)
> +			<< "Please consider updating the sensor database";
> +		return nullptr;
> +	}
> +
> +	return it->second;
> +}
> +
> +} /* namespace libcamera */

-- 
Regards,

Laurent Pinchart