[libcamera-devel] [PATCH 3/4] libcamera: camera_lens: Add a new class to model a camera lens
Hanlin Chen
hanlinchen at chromium.org
Fri Oct 29 11:38:25 CEST 2021
Hi Kieran,
Thanks for the review.
On Fri, Oct 29, 2021 at 12:55 AM Kieran Bingham
<kieran.bingham at ideasonboard.com> wrote:
>
> Quoting Han-Lin Chen (2021-10-28 11:03:18)
> > The CameraLens class abstracts camera lens and provides helper
> > functions to ease interactions with them.
> >
> > Signed-off-by: Han-Lin Chen <hanlinchen at chromium.com>
> > ---
> > Documentation/index.rst | 1 +
> > Documentation/lens_driver_requirements.rst | 28 ++
> > Documentation/meson.build | 1 +
> > include/libcamera/internal/camera_lens.h | 61 +++++
> > src/libcamera/camera_lens.cpp | 289 +++++++++++++++++++++
> > src/libcamera/meson.build | 1 +
> > 6 files changed, 381 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..226cb813
> > --- /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
> > +==========================
>
> two extra '==' could be removed.
>
> > +
> > +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
>
> Seeing that there is also V4L2_CID_FOCUS_RELATIVE, I assume that some
> drivers might offer a different means to control.
>
> Would an algorithm be able to be more general if it supported RELATIVE?
> or are they always expected to know how to operate the lens motor and
> have an absolute position request.
>
> I suspect the V4L2_CID_FOCUS_ABSOLUTE is the only way to get the valid
> range of movement out anyway, so I think this is appropriate.
>
>
> > diff --git a/Documentation/meson.build b/Documentation/meson.build
> > index df36a808..746af4cf 100644
> > --- a/Documentation/meson.build
> > +++ b/Documentation/meson.build
> > @@ -60,6 +60,7 @@ if sphinx.found()
> > 'guides/ipa.rst',
> > 'guides/pipeline-handler.rst',
> > 'guides/tracing.rst',
> > + 'lens_driver_requirements.rst',
>
> alphabetical order here please.
>
> > 'index.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..f03de5fc
> > --- /dev/null
> > +++ b/include/libcamera/internal/camera_lens.h
> > @@ -0,0 +1,61 @@
> > +/* 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>
> > +#include "libcamera/internal/v4l2_subdevice.h"
> > +
> > +namespace libcamera {
> > +
> > +class MediaEntity;
> > +
> > +class CameraLens : protected Loggable
> > +{
> > +public:
> > + explicit CameraLens(const MediaEntity *entity);
> > + ~CameraLens();
> > +
> > + int init();
> > +
> > + const std::string &model() const { return model_; }
> > + const std::string &id() const { return id_; }
> > + 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/src/libcamera/camera_lens.cpp b/src/libcamera/camera_lens.cpp
> > new file mode 100644
> > index 00000000..0c80d3c3
> > --- /dev/null
> > +++ b/src/libcamera/camera_lens.cpp
> > @@ -0,0 +1,289 @@
> > +/* 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 "libcamera/internal/media_device.h"
> > +
> > +#include <regex>
> > +
> > +#include <libcamera/property_ids.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 Destroy a CameraLens
> > + */
> > +CameraLens::~CameraLens()
> > +{
> > +}
> > +
> > +/**
> > + * \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";
>
> This goes over 120 chars, perhaps another line break?
> Even the message is over 90 chars, so might be better for users if it was split.
>
> > + 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_));
> > +
> > + /* Generate a unique ID for the lens. */
> > + int ret = generateId();
>
> Does a lens need an ID like this? Can't it just be referenced as the
> object when needed?
>
> Perhaps it will become clearer later.
>
> Will there ever be more than one lens per 'Camera'?
It's an interesting question :). I cannot find an actual example.
Since we don't have any use case for Id, I will remove it on the next
patch (and other problems).
>
>
> > + if (ret)
> > + return ret;
> > +
> > + 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
> > + * \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() + "'";
> > +}
> > +
> > +int CameraLens::generateId()
> > +{
> > + const std::string devPath = subdev_->devicePath();
> > +
> > + /* Try to get ID from firmware description. */
> > + id_ = sysfs::firmwareNodePath(devPath);
> > + if (!id_.empty())
> > + return 0;
> > +
> > + /*
> > + * Virtual lens not described in firmware
> > + *
> > + * Verify it's a platform device and construct ID from the device path
> > + * and model of lens.
> > + */
> > + if (devPath.find("/sys/devices/platform/", 0) == 0) {
> > + id_ = devPath.substr(strlen("/sys/devices/")) + " " + model();
> > + return 0;
> > + }
> > +
> > + LOG(CameraLens, Error) << "Can't generate lens ID";
> > + return -EINVAL;
> > +}
> > +
> > +} /* 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',
> > --
> > 2.33.1.1089.g2158813163f-goog
> >
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