[libcamera-devel] [PATCH v5 2/5] libcamera: camera_sensor: Generate a sensor ID
Laurent Pinchart
laurent.pinchart at ideasonboard.com
Sun Aug 2 20:26:55 CEST 2020
Hi Niklas,
Thank you for the patch.
On Wed, Jul 29, 2020 at 01:50:52PM +0200, Niklas Söderlund wrote:
> Generate a constant and unique string ID for the sensor. The ID is
> generated from information from the firmware description of the camera
> image sensor. The ID is unique and persistent across reboots of the
> system.
>
> For OF based systems the ID is the full path of the sensors in the
> device tree description. For ACPI based systems the ID is the ACPI
> firmware nodes path. Both ID sources are guaranteed to be unique and
> persistent as long as the firmware of the system is not changed.
>
> A special case is needed to deal with the VIMC pipeline that implements
> a virtual pipeline that is not backed by any hardware device and is
> therefore not described in the device firmware.
>
> Signed-off-by: Niklas Söderlund <niklas.soderlund at ragnatech.se>
> Reviewed-by: Jacopo Mondi <jacopo at jmondi.org>
> Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
> ---
> * Changes since v4
> - Fix spelling.
>
> * Changes since v3
> - Update commit message.
> - Add description of how ID are generated to comment.
> ---
> include/libcamera/internal/camera_sensor.h | 4 +
> src/libcamera/camera_sensor.cpp | 94 ++++++++++++++++++++++
> 2 files changed, 98 insertions(+)
>
> diff --git a/include/libcamera/internal/camera_sensor.h b/include/libcamera/internal/camera_sensor.h
> index 06c8292ca30129de..e0d2d9f63b47c2fe 100644
> --- a/include/libcamera/internal/camera_sensor.h
> +++ b/include/libcamera/internal/camera_sensor.h
> @@ -47,6 +47,7 @@ public:
> int init();
>
> const std::string &model() const { return model_; }
> + const std::string &id() const { return id_; }
> const MediaEntity *entity() const { return entity_; }
> const std::vector<unsigned int> &mbusCodes() const { return mbusCodes_; }
> const std::vector<Size> &sizes() const { return sizes_; }
> @@ -67,11 +68,14 @@ protected:
> std::string logPrefix() const override;
>
> private:
> + int generateID();
> +
> const MediaEntity *entity_;
> std::unique_ptr<V4L2Subdevice> subdev_;
> unsigned int pad_;
>
> std::string model_;
> + std::string id_;
>
> V4L2Subdevice::Formats formats_;
> Size resolution_;
> diff --git a/src/libcamera/camera_sensor.cpp b/src/libcamera/camera_sensor.cpp
> index 350f49accad99c7b..6dc616945dad5ef1 100644
> --- a/src/libcamera/camera_sensor.cpp
> +++ b/src/libcamera/camera_sensor.cpp
> @@ -9,10 +9,12 @@
>
> #include <algorithm>
> #include <float.h>
> +#include <fstream>
> #include <iomanip>
> #include <limits.h>
> #include <math.h>
> #include <regex>
> +#include <sys/stat.h>
>
> #include <libcamera/property_ids.h>
>
> @@ -204,6 +206,11 @@ int CameraSensor::init()
> if (ret < 0)
> return ret;
>
> + /* Generate a unique ID for the sensor. */
> + ret = generateID();
> + if (ret)
> + return ret;
> +
> /* Retrieve and store the camera sensor properties. */
> const ControlInfoMap &controls = subdev_->controls();
> int32_t propertyValue;
> @@ -283,6 +290,26 @@ int CameraSensor::init()
> * \return The sensor model name
> */
>
> +/**
> + * \fn CameraSensor::id()
> + * \brief Retrieve the sensor ID
> + *
> + * The sensor ID is a free-formed string that uniquely identifies the sensor in
> + * the system. The ID is persistent between different instances of libcamera and
> + * between resets of the system.
> + *
> + * For OF based systems the ID is the full path of the sensors in the device
> + * tree description. For ACPI based systems the ID is the ACPI firmware nodes
> + * path. Both ID sources are guaranteed to be unique and persistent as long as
> + * the firmware of the system is not changed.
> + *
> + * A special case is needed to deal with the VIMC pipeline that implements a
> + * virtual pipeline that is not backed by any hardware device and is therefore
> + * not described in the device firmware.
> + *
> + * \return The sensor ID
> + */
> +
> /**
> * \fn CameraSensor::entity()
> * \brief Retrieve the sensor media entity
> @@ -541,4 +568,71 @@ std::string CameraSensor::logPrefix() const
> return "'" + entity_->name() + "'";
> }
>
> +int CameraSensor::generateID()
> +{
> + std::string path, devPath = subdev_->devicePath();
We usually split declarations on multiple lines.
> + struct stat statbuf;
> +
> + /* Try to generate ID from OF device tree path. */
> + path = devPath + "/of_node";
> + if (stat(path.c_str(), &statbuf) == 0) {
You can use
if (!File::exists(path)) {
> + char ofPath[PATH_MAX];
> +
> + if (!realpath(path.c_str(), ofPath)) {
As mentioned in the review of 1/5, should we use realpath with nullptr
as the second argument ? Or maybe just use readlink() with PATH_MAX ?
> + LOG(CameraSensor, Error) << "Failed to read sensor OF based ID";
s/OF based/OF-based/
> + return -EINVAL;
> + }
> +
> + id_ = ofPath;
> + const std::string dropStr = "/sys/firmware/devicetree/";
static const ?
Same comments for the other options below.
> + if (id_.find(dropStr) == 0)
> + id_.erase(0, dropStr.length());
> +
> + return 0;
> + }
> +
> + /* Try to generate ID from ACPI path. */
> + path = devPath + "/firmware_node/path";
> + if (stat(path.c_str(), &statbuf) == 0) {
> + std::ifstream file(path.c_str());
> +
> + if (!file.is_open()) {
> + LOG(CameraSensor, Error) << "Failed to read sensor ACPI based ID";
> + return -EINVAL;
> + }
> +
> + std::getline(file, id_);
> + file.close();
> +
> + return 0;
> + }
> +
> + /*
> + * VIMC is a virtual video pipeline not backed hardware and has no OF
> + * or ACPI firmware nodes. Handle this pipeline as a special case and
> + * generate IDs based on the sensor model.
> + */
> + path = devPath + "/modalias";
> + if (stat(path.c_str(), &statbuf) == 0) {
> + std::ifstream file(path.c_str());
> +
> + if (!file.is_open()) {
> + LOG(CameraSensor, Error) << "Failed to read sensor ACPI based ID";
> + return -EINVAL;
> + }
> +
> + std::string modalias;
> + std::getline(file, modalias);
> + file.close();
> +
> + if (modalias == "platform:vimc") {
> + id_ = "VIMC " + model();
> + return 0;
> + }
Should we make this case more generic with the following (pseudo-code) ?
id_ = basename(readlink(devPath + "/device")) + "/" + model_;
> + }
> +
> + LOG(CameraSensor, Error) << "Unknown sensor device type, can not generate ID";
> + return -EINVAL;
> +}
> +
> } /* namespace libcamera */
--
Regards,
Laurent Pinchart
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