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

[Jean-Michel Hautbois]

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 },
+		} },
+	};
 
 	const auto it = lensProps.find(lens);
 	if (it == lensProps.end()) {
-- 
2.34.1