[libcamera-devel] [RFC PATCH 3/4] libcamera: lens: Add a helper to get the fixed range lens values

[Laurent Pinchart]

On Thu, Jun 09, 2022 at 08:03:05AM +0200, Jean-Michel Hautbois via libcamera-devel wrote:
> When the focus algorithm runs, it can be asked to go to a specific
> position, through the controls::LensPosition control. Those controls
> need specific values to be known, in particular the minimum and maximum
> value the driver can set to the lens to make it move to a given
> position.
> 
> Add a new helper on the camera lens side to get this range or a default
> nulled structure if it is not available. This particular value needs to
> be taken into account by the caller and it shall use the minimum and
> maximum reported by the driver.
> 
> Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois at ideasonboard.com>
> ---
>  include/libcamera/internal/camera_lens.h      |  1 +
>  .../internal/camera_lens_properties.h         |  2 ++
>  src/libcamera/camera_lens.cpp                 | 19 +++++++++++++++++++
>  src/libcamera/camera_lens_properties.cpp      |  9 ++++++++-
>  4 files changed, 30 insertions(+), 1 deletion(-)
> 
> diff --git a/include/libcamera/internal/camera_lens.h b/include/libcamera/internal/camera_lens.h
> index 523a1481..f6daff01 100644
> --- a/include/libcamera/internal/camera_lens.h
> +++ b/include/libcamera/internal/camera_lens.h
> @@ -29,6 +29,7 @@ public:
>  
>  	int init();
>  	int setFocusPosition(int32_t position);
> +	const Size &getLensRange();
>  
>  	const std::string &model() const { return model_; }
>  
> diff --git a/include/libcamera/internal/camera_lens_properties.h b/include/libcamera/internal/camera_lens_properties.h
> index 73982550..7424b375 100644
> --- a/include/libcamera/internal/camera_lens_properties.h
> +++ b/include/libcamera/internal/camera_lens_properties.h
> @@ -17,6 +17,8 @@ namespace libcamera {
>  
>  struct CameraLensProperties {
>  	static const CameraLensProperties *get(const std::string &lens);
> +
> +	Size lensFocusRange;
>  };
>  
>  } /* namespace libcamera */
> diff --git a/src/libcamera/camera_lens.cpp b/src/libcamera/camera_lens.cpp
> index d4d44bc7..abec5a27 100644
> --- a/src/libcamera/camera_lens.cpp
> +++ b/src/libcamera/camera_lens.cpp
> @@ -79,6 +79,25 @@ int CameraLens::init()
>  	return 0;
>  }
>  
> +/**
> + * \brief Retrieve the lens position range
> + * \return The minimum and maximum positions for the given lens or a default
> + * nulled Size reference
> + *
> + * If a lens has no static properties associated, a special value is returned,
> + * where the minimum and maximum are set to 0. The caller may then chose the
> + * ones returned by the V4L2_CID_FOCUS_ABSOLUTE call.
> + */
> +const Size &CameraLens::getLensRange()
> +{
> +	static const Size defaultLensFocusRange = { 0, 0 };
> +	if (!staticProps_ || staticProps_->lensFocusRange.isNull())
> +		return defaultLensFocusRange;
> +
> +	return staticProps_->lensFocusRange;
> +}
> +
> +
>  /**
>   * \brief This function sets the focal point of the lens to a specific position.
>   * \param[in] position The focal point of the lens
> diff --git a/src/libcamera/camera_lens_properties.cpp b/src/libcamera/camera_lens_properties.cpp
> index dee73b43..225546ae 100644
> --- a/src/libcamera/camera_lens_properties.cpp
> +++ b/src/libcamera/camera_lens_properties.cpp
> @@ -32,6 +32,9 @@ LOG_DEFINE_CATEGORY(CameraLensProperties)
>  /**
>   * \struct CameraLensProperties
>   * \brief Database of camera lens properties
> + *
> + * \var CameraLensProperties::lensFocusRange
> + * \brief The limits for the sensor position, stored as a min and a max.
>   */
>  
>  /**
> @@ -42,7 +45,11 @@ LOG_DEFINE_CATEGORY(CameraLensProperties)
>   */
>  const CameraLensProperties *CameraLensProperties::get(const std::string &lens)
>  {
> -	static const std::map<std::string, const CameraLensProperties> lensProps = {};
> +	static const std::map<std::string, const CameraLensProperties> lensProps = {
> +		{ "dw9714", {
> +				.lensFocusRange = { 150, 800 },
> +		} },
> +	};

This partly answers the question I asked in a reply to the cover letter.

What makes you think the lens focus range is an intrinsic property of
the VCM driver ?

>  
>  	const auto it = lensProps.find(lens);
>  	if (it == lensProps.end()) {

-- 
Regards,

Laurent Pinchart