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

[Jacopo Mondi]

On Tue, Apr 27, 2021 at 09:47:35AM +0300, Laurent Pinchart wrote:
> 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,

What's the CameraSensorProperties class ?

> 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 },
> 		} },

Thinking forward, when the sensor db will have more fields, I think
declaring the map using the macro is more compact. I can drop it if
you feel strongly about this.

> 	};
>
> > +
> > +	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