[libcamera-devel] [PATCH v6 2/4] libcamera: add model() for retriving model name in V4L2Subdevice

[Kieran Bingham]

Quoting Han-Lin Chen (2021-11-30 10:51:55)
> CameraSensor retrives model name from media entity. Move the heuristics
> method into V4L2Subdevice, so CameraLens can reuse the function.
> 

(The following line should be added while applying or for a next
version if needed).

"While here, fix a small typo for 'device'."

> Signed-off-by: Han-Lin Chen <hanlinchen at chromium.org>
> ---
>  include/libcamera/internal/v4l2_subdevice.h |  4 ++
>  src/libcamera/camera_sensor.cpp             | 32 +---------------
>  src/libcamera/v4l2_subdevice.cpp            | 42 +++++++++++++++++++++
>  3 files changed, 48 insertions(+), 30 deletions(-)
> 
> diff --git a/include/libcamera/internal/v4l2_subdevice.h b/include/libcamera/internal/v4l2_subdevice.h
> index 97b89fb9..763c4dec 100644
> --- a/include/libcamera/internal/v4l2_subdevice.h
> +++ b/include/libcamera/internal/v4l2_subdevice.h
> @@ -61,6 +61,8 @@ public:
>         int setFormat(unsigned int pad, V4L2SubdeviceFormat *format,
>                       Whence whence = ActiveFormat);
>  
> +       std::string model();
> +
>         static std::unique_ptr<V4L2Subdevice>
>         fromEntityName(const MediaDevice *media, const std::string &entity);
>  
> @@ -75,6 +77,8 @@ private:
>                                             unsigned int code);
>  
>         const MediaEntity *entity_;
> +
> +       std::string model_;
>  };
>  
>  } /* namespace libcamera */
> diff --git a/src/libcamera/camera_sensor.cpp b/src/libcamera/camera_sensor.cpp
> index 9fdb8c09..6151b32e 100644
> --- a/src/libcamera/camera_sensor.cpp
> +++ b/src/libcamera/camera_sensor.cpp
> @@ -13,7 +13,6 @@
>  #include <iomanip>
>  #include <limits.h>
>  #include <math.h>
> -#include <regex>
>  #include <string.h>
>  
>  #include <libcamera/property_ids.h>
> @@ -347,34 +346,7 @@ void CameraSensor::initTestPatternModes(
>  
>  int CameraSensor::initProperties()
>  {
> -       /*
> -        * Extract the camera sensor model name from the media entity name.
> -        *
> -        * There is no standardized naming scheme for sensor entities in the
> -        * Linux kernel at the moment.
> -        *
> -        * - The most common rule, used by I2C sensors, associates the model
> -        *   name with the I2C bus number and address (e.g. 'imx219 0-0010').
> -        *
> -        * - When the sensor exposes multiple subdevs, the model name is
> -        *   usually followed by a function name, as in the smiapp driver (e.g.
> -        *   'jt8ew9 pixel_array 0-0010').
> -        *
> -        * - The vimc driver names its sensors 'Sensor A' and 'Sensor B'.
> -        *
> -        * 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;
> -
> +       model_ = subdev_->model();
>         properties_.set(properties::Model, utils::toAscii(model_));
>  
>         /* Generate a unique ID for the sensor. */
> @@ -832,7 +804,7 @@ int CameraSensor::generateId()
>         /*
>          * Virtual sensors not described in firmware
>          *
> -        * Verify it's a platform device and construct ID from the deive path
> +        * Verify it's a platform device and construct ID from the device path
>          * and model of sensor.
>          */
>         if (devPath.find("/sys/devices/platform/", 0) == 0) {
> diff --git a/src/libcamera/v4l2_subdevice.cpp b/src/libcamera/v4l2_subdevice.cpp
> index 023e2328..17ec9fdf 100644
> --- a/src/libcamera/v4l2_subdevice.cpp
> +++ b/src/libcamera/v4l2_subdevice.cpp
> @@ -9,6 +9,7 @@
>  
>  #include <fcntl.h>
>  #include <iomanip>
> +#include <regex>
>  #include <sstream>
>  #include <string.h>
>  #include <sys/ioctl.h>
> @@ -442,6 +443,47 @@ int V4L2Subdevice::setFormat(unsigned int pad, V4L2SubdeviceFormat *format,
>         return 0;
>  }
>  
> +/**
> + * \brief Retrieve the model name
> + * \return The model name of the device
> + */
> +std::string V4L2Subdevice::model()
> +{
> +       if (!model_.empty())
> +               return model_;
> +

We don't normally use lazy initialisation, but I think this is OK in
this case.

Maybe we might have a subdevice which doesn't ever read the model, so
there wouldn't be any point parsing the information...

And it can't be accessed uninitialised, so it seems fine to me.


Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>


> +       /*
> +        * Extract model name from the media entity name.
> +        *
> +        * There is no standardized naming scheme for sensor entities in the
> +        * Linux kernel at the moment.
> +        *
> +        * - The most common rule, used by I2C sensors, associates the model
> +        *   name with the I2C bus number and address (e.g. 'imx219 0-0010').
> +        *
> +        * - When the sensor exposes multiple subdevs, the model name is
> +        *   usually followed by a function name, as in the smiapp driver (e.g.
> +        *   'jt8ew9 pixel_array 0-0010').
> +        *
> +        * - The vimc driver names its sensors 'Sensor A' and 'Sensor B'.
> +        *
> +        * 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;
> +
> +       std::string model;
> +       if (std::regex_search(entityName, match, i2cRegex))
> +               model_ = entityName.substr(0, entityName.find(' '));
> +       else
> +               model_ = entityName;
> +
> +       return model_;
> +}
> +
>  /**
>   * \brief Create a new video subdevice instance from \a entity in media device
>   * \a media
> -- 
> 2.34.0.rc2.393.gf8c9666880-goog
>