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

[Jean-Michel Hautbois]

Hi Laurent,

On 09/06/2022 11:34, Laurent Pinchart wrote:
> 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 ?

I am not sure of this indeed, probably it will be a couple lens/sensor 
model... And what else do we have than the vcm driver ?
I don't have any tune files as example from "real life" so I don't 
really know what is usually done, any insight will be appreciated ;-).

Thanks,
JM

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