[libcamera-devel] [PATCH v3 2/3] libcamera: camera_lens: Add a new class to model a camera lens
Kieran Bingham
kieran.bingham at ideasonboard.com
Fri Nov 19 17:09:11 CET 2021
Quoting Han-Lin Chen (2021-11-11 10:49:57)
> The CameraLens class abstracts camera lens and provides helper
> functions to ease interactions with them.
>
> Signed-off-by: Han-Lin Chen <hanlinchen at chromium.org>
> ---
> Documentation/index.rst | 1 +
> Documentation/lens_driver_requirements.rst | 28 +++
> Documentation/meson.build | 1 +
> include/libcamera/internal/camera_lens.h | 60 +++++
> include/libcamera/internal/meson.build | 1 +
> src/libcamera/camera_lens.cpp | 253 +++++++++++++++++++++
> src/libcamera/meson.build | 1 +
> 7 files changed, 345 insertions(+)
> create mode 100644 Documentation/lens_driver_requirements.rst
> create mode 100644 include/libcamera/internal/camera_lens.h
> create mode 100644 src/libcamera/camera_lens.cpp
>
> diff --git a/Documentation/index.rst b/Documentation/index.rst
> index 1f4fc485..0ee10044 100644
> --- a/Documentation/index.rst
> +++ b/Documentation/index.rst
> @@ -21,3 +21,4 @@
> Tracing guide <guides/tracing>
> Environment variables <environment_variables>
> Sensor driver requirements <sensor_driver_requirements>
> + Lens driver requirements <lens_driver_requirements>
> diff --git a/Documentation/lens_driver_requirements.rst b/Documentation/lens_driver_requirements.rst
> new file mode 100644
> index 00000000..afc300cf
> --- /dev/null
> +++ b/Documentation/lens_driver_requirements.rst
> @@ -0,0 +1,28 @@
> +.. SPDX-License-Identifier: CC-BY-SA-4.0
> +
> +.. _lens-driver-requirements:
> +
> +Lens Driver Requirements
> +========================
> +
> +libcamera handles lens devices in the CameraLens class and defines
> +a consistent interface through its API towards other library components.
> +
> +The CameraLens class uses the V4L2 subdev kernel API to interface with the
> +camera lens through one or multiple sub-devices exposed in userspace by
> +the lens driver.
> +
> +In order for libcamera to be fully operational and provide all the required
> +information to interface with the camera lens to applications and pipeline
> +handlers, a set of mandatory features the driver has to support has been defined.
> +
> +Mandatory Requirements
> +----------------------
> +
> +The lens driver is assumed to be fully compliant with the V4L2 specification.
> +
> +The lens driver shall support the following V4L2 controls:
> +
> +* `V4L2_CID_FOCUS_ABSOLUTE`_
> +
> +.. _V4L2_CID_FOCUS_ABSOLUTE: https://www.kernel.org/doc/html/latest/userspace-api/media/v4l/ext-ctrls-camera.html
> diff --git a/Documentation/meson.build b/Documentation/meson.build
> index 4c972675..33af82aa 100644
> --- a/Documentation/meson.build
> +++ b/Documentation/meson.build
> @@ -66,6 +66,7 @@ if sphinx.found()
> 'guides/pipeline-handler.rst',
> 'guides/tracing.rst',
> 'index.rst',
> + 'lens_driver_requirements.rst',
> 'sensor_driver_requirements.rst',
> '../README.rst',
> ]
> diff --git a/include/libcamera/internal/camera_lens.h b/include/libcamera/internal/camera_lens.h
> new file mode 100644
> index 00000000..fba5d1fa
> --- /dev/null
> +++ b/include/libcamera/internal/camera_lens.h
> @@ -0,0 +1,60 @@
> +/* SPDX-License-Identifier: LGPL-2.1-or-later */
> +/*
> + * Copyright (C) 2021, Google Inc.
> + *
> + * camera_lens.h - A camera lens
> + */
> +#ifndef __LIBCAMERA_INTERNAL_CAMERA_LENS_H__
> +#define __LIBCAMERA_INTERNAL_CAMERA_LENS_H__
> +
> +#include <libcamera/base/class.h>
> +#include <libcamera/base/log.h>
> +
> +#include <libcamera/controls.h>
Our checkstyle doesn't cope well with highlighting diffs on new files.
If fixed, it would report a new line to add here
This could be fixed while applying.
> +#include "libcamera/internal/v4l2_subdevice.h"
> +
> +namespace libcamera {
> +
> +class MediaEntity;
> +
> +class CameraLens : protected Loggable
> +{
> +public:
> + explicit CameraLens(const MediaEntity *entity);
> + ~CameraLens() = default;
> +
> + int init();
> +
> + const std::string &model() const { return model_; }
> + const MediaEntity *entity() const { return entity_; }
> +
> + const ControlInfoMap &controls() const;
> + ControlList getControls(const std::vector<uint32_t> &ids);
> + int setControls(ControlList *ctrls);
> +
> + V4L2Subdevice *device() { return subdev_.get(); }
> +
> + const ControlList &properties() const { return properties_; }
> +
> +protected:
> + std::string logPrefix() const override;
> +
> +private:
> + LIBCAMERA_DISABLE_COPY(CameraLens)
> +
> + int generateId();
> + int validateLensDriver();
> + int initProperties();
> +
> + const MediaEntity *entity_;
> + std::unique_ptr<V4L2Subdevice> subdev_;
> +
> + std::string model_;
> + std::string id_;
> +
> + ControlList properties_;
> +};
> +
> +} /* namespace libcamera */
> +
> +#endif /* __LIBCAMERA_INTERNAL_CAMERA_LENS_H__ */
> diff --git a/include/libcamera/internal/meson.build b/include/libcamera/internal/meson.build
> index 665fd6de..a96bbb95 100644
> --- a/include/libcamera/internal/meson.build
> +++ b/include/libcamera/internal/meson.build
> @@ -14,6 +14,7 @@ libcamera_internal_headers = files([
> 'byte_stream_buffer.h',
> 'camera.h',
> 'camera_controls.h',
> + 'camera_lens.h',
> 'camera_sensor.h',
> 'camera_sensor_properties.h',
> 'control_serializer.h',
> diff --git a/src/libcamera/camera_lens.cpp b/src/libcamera/camera_lens.cpp
> new file mode 100644
> index 00000000..944f807e
> --- /dev/null
> +++ b/src/libcamera/camera_lens.cpp
> @@ -0,0 +1,253 @@
> +/* SPDX-License-Identifier: LGPL-2.1-or-later */
> +/*
> + * Copyright (C) 2021, Google Inc.
> + *
> + * camera_lens.cpp - A camera lens
> + */
> +
> +#include "libcamera/internal/camera_lens.h"
> +
> +#include <regex>
> +#include <libcamera/property_ids.h>
> +
> +#include "libcamera/internal/media_device.h"
> +#include "libcamera/internal/sysfs.h"
> +
> +/**
> + * \file camera_lens.h
> + * \brief A camera lens
> + */
> +
> +namespace libcamera {
> +
> +LOG_DEFINE_CATEGORY(CameraLens)
> +
> +/**
> + * \class CameraLens
> + * \brief A camera lens based on V4L2 subdevices
> + *
> + * The CameraLens class eases handling of lens for pipeline handlers by
> + * hiding the details of the V4L2 subdevice kernel API and caching lens
> + * information.
> + *
> + * The implementation is currently limited to lens that expose a single V4L2
> + * subdevice. It will be extended to support more complex devices as the needs
> + * arise.
> + */
> +
> +/**
> + * \brief Construct a CameraLens
> + * \param[in] entity The media entity backing the camera lens
> + *
> + * Once constructed the instance must be initialized with init().
> + */
> +CameraLens::CameraLens(const MediaEntity *entity)
> + : entity_(entity),
> + properties_(properties::properties)
> +{
> +}
> +
> +/**
> + * \brief Initialize the camera lens instance
> + *
> + * This function performs the initialisation steps of the CameraLens that may
> + * fail. It shall be called once and only once after constructing the instance.
> + *
> + * \return 0 on success or a negative error code otherwise
> + */
> +int CameraLens::init()
> +{
> + if (entity_->function() != MEDIA_ENT_F_LENS) {
> + LOG(CameraLens, Error)
> + << "Invalid lens function "
> + << utils::hex(entity_->function());
> + return -EINVAL;
> + }
> +
> + /* Create and open the subdev. */
> + subdev_ = std::make_unique<V4L2Subdevice>(entity_);
> + int ret = subdev_->open();
> + if (ret < 0)
> + return ret;
> +
> + ret = validateLensDriver();
> + if (ret)
> + return ret;
> +
> + ret = initProperties();
> + if (ret)
> + return ret;
> +
> + return 0;
> +}
> +
> +int CameraLens::validateLensDriver()
> +{
> + int err = 0;
> + static constexpr uint32_t mandatoryControls[] = {
> + V4L2_CID_FOCUS_ABSOLUTE
> + };
> +
> + const ControlInfoMap &controls = subdev_->controls();
> + for (uint32_t ctrl : mandatoryControls) {
> + if (!controls.count(ctrl)) {
> + LOG(CameraLens, Error)
> + << "Mandatory V4L2 control " << utils::hex(ctrl)
> + << " not available";
> + err = -EINVAL;
> + }
> + }
> +
> + if (err) {
> + LOG(CameraLens, Error)
> + << "The lens kernel driver needs to be fixed";
> + LOG(CameraLens, Error)
> + << "See Documentation/lens_driver_requirements.rst in"
> + << " the libcamera sources for more information";
> + return err;
> + }
> +
> + return 0;
> +}
> +
> +int CameraLens::initProperties()
> +{
> + /*
> + * Extract the camera lens model name from the media entity name.
> + *
> + * There is no standardized naming scheme for lens entities in the
> + * Linux kernel at the moment.
> + *
> + * - The most common rule, used by I2C lens, associates the model
> + * name with the I2C bus number and address (e.g. 'dw9714 8-000c').
> + *
> + * Other schemes probably exist. As a best effort heuristic, use the
> + * part of the entity name before the first space if the name contains
> + * an I2C address, and use the full entity name otherwise.
> + */
> + std::string entityName = entity_->name();
> + std::regex i2cRegex{ " [0-9]+-[0-9a-f]{4}" };
> + std::smatch match;
> +
> + if (std::regex_search(entityName, match, i2cRegex))
> + model_ = entityName.substr(0, entityName.find(' '));
> + else
> + model_ = entityName;
> +
> + properties_.set(properties::Model, utils::toAscii(model_));
> +
> + return 0;
> +}
> +
> +/**
> + * \fn CameraLens::model()
> + * \brief Retrieve the lens model name
> + *
> + * The lens model name is a free-formed string that uniquely identifies the
> + * lens model.
> + *
> + * \return The lens model name
> + */
> +
> +/**
> + * \fn CameraLens::id()
> + * \brief Retrieve the lens ID
> + *
> + * The lens ID is a free-form string that uniquely identifies the lens in
> + * the system.
> + *
> + * \return The lens ID
> + */
> +
> +/**
> + * \fn CameraLens::entity()
> + * \brief Retrieve the lens media entity
> + * \return The lens media entity
> + */
> +
> +/**
> + * \brief Retrieve the supported V4L2 controls and their information
> + *
> + * Control information is updated automatically to reflect the current lens
> + * configuration when the setFormat() function is called, without invalidating
> + * any iterator on the ControlInfoMap.
> + *
> + * \return A map of the V4L2 controls supported by the lens
> + */
> +const ControlInfoMap &CameraLens::controls() const
> +{
> + return subdev_->controls();
> +}
> +
> +/**
> + * \brief Read V4L2 controls from the lens
> + * \param[in] ids The list of controls to read, specified by their ID
> + *
> + * This function reads the value of all controls contained in \a ids, and
> + * returns their values as a ControlList. The control identifiers are defined by
> + * the V4L2 specification (V4L2_CID_*).
> + *
> + * 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
> + * function returns an empty control list.
> + *
> + * \sa V4L2Device::getControls()
> + *
> + * \return The control values in a ControlList on success, or an empty list on
> + * error
> + */
> +ControlList CameraLens::getControls(const std::vector<uint32_t> &ids)
> +{
> + return subdev_->getControls(ids);
> +}
> +
> +/**
> + * \brief Write V4L2 controls to the lens
> + * \param[in] ctrls The list of controls to write
> + *
> + * This function 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. The control identifiers are defined by the V4L2 specification
> + * (V4L2_CID_*).
> + *
> + * 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, or if any other
> + * error occurs during validation of the requested controls, no control is
> + * written and this function 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.
> + *
> + * \sa V4L2Device::setControls()
> + *
> + * \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 CameraLens::setControls(ControlList *ctrls)
> +{
> + return subdev_->setControls(ctrls);
> +}
> +
> +/**
> + * \fn CameraLens::device()
> + * \brief Retrieve the camera lens device
> + * \todo Remove this function by integrating DelayedControl with CameraLens
Do VCM controls need to be delayed? Or is this just to be able to
synchronise what position was applied to a given frame?
No objection to keeping this as a todo though as we still need to
investigate and figure out how DelayedControls works with multiple
devices in that case.
Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
I see this and the previous patch as definite building blocks that are
going to be useful moving forwards.
> + * \return The camera lens device
> + */
> +
> +/**
> + * \fn CameraLens::properties()
> + * \brief Retrieve the camera lens properties
> + * \return The list of camera lens properties
> + */
> +
> +std::string CameraLens::logPrefix() const
> +{
> + return "'" + entity_->name() + "'";
> +}
> +
> +} /* namespace libcamera */
> diff --git a/src/libcamera/meson.build b/src/libcamera/meson.build
> index 6727a777..3bee8fee 100644
> --- a/src/libcamera/meson.build
> +++ b/src/libcamera/meson.build
> @@ -5,6 +5,7 @@ libcamera_sources = files([
> 'byte_stream_buffer.cpp',
> 'camera.cpp',
> 'camera_controls.cpp',
> + 'camera_lens.cpp',
> 'camera_manager.cpp',
> 'camera_sensor.cpp',
> 'camera_sensor_properties.cpp',
> --
> 2.34.0.rc1.387.gb447b232ab-goog
>
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