[libcamera-devel] [PATCH] libcamera: camera_sensor: Cap resolution to max frame size

[Jacopo Mondi]

Since commit 96aecfe36508 ("libcamera: camera_sensor: Use active area
size as resolution") the CameraSensor::resolution() method returned the
sensor's active pixel area size.

As the CameraSensor::resolution() method is widely used in the library
code base to retrieve the maximum frame size the sensor can produce,
in case it is smaller than the pixel area size the returned size cannot
be used to configure the sensor correctly.

Fix this by returning the maximum frame resolution the sensor can
produce, or the pixel area size in case the sensor embeds and ISP that
can upscale and the supported maximum frame size is thus larger that
the pixel array size.

Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>
---
 include/libcamera/internal/camera_sensor.h |  2 +-
 src/libcamera/camera_sensor.cpp            | 14 +++++++++++++-
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/include/libcamera/internal/camera_sensor.h b/include/libcamera/internal/camera_sensor.h
index 71d012f795fe..3e98f71b5e7f 100644
--- a/include/libcamera/internal/camera_sensor.h
+++ b/include/libcamera/internal/camera_sensor.h
@@ -53,7 +53,7 @@ public:
 	const MediaEntity *entity() const { return entity_; }
 	const std::vector<unsigned int> &mbusCodes() const { return mbusCodes_; }
 	const std::vector<Size> &sizes() const { return sizes_; }
-	Size resolution() const { return activeArea_.size(); }
+	Size resolution() const;

 	V4L2SubdeviceFormat getFormat(const std::vector<unsigned int> &mbusCodes,
 				      const Size &size) const;
diff --git a/src/libcamera/camera_sensor.cpp b/src/libcamera/camera_sensor.cpp
index a04982971616..edc2c27084ed 100644
--- a/src/libcamera/camera_sensor.cpp
+++ b/src/libcamera/camera_sensor.cpp
@@ -551,10 +551,22 @@ int CameraSensor::initProperties()
  */

 /**
- * \fn CameraSensor::resolution()
  * \brief Retrieve the camera sensor resolution
+ *
+ * The camera sensor resolution is the largest frame size the sensor can produce
+ * or, if the camera sensor embeds and ISP that can up-scale, the pixel area
+ * size.
+ *
+ * \todo Consider if it desirable to distinguish between the maximum resolution
+ * the sensor can produce (also including upscaled ones) and the actual pixel
+ * array size by splitting this method in two.
+ *
  * \return The camera sensor resolution in pixels
  */
+Size CameraSensor::resolution() const
+{
+	return std::min(sizes_.back(), activeArea_.size());
+}

 /**
  * \brief Retrieve the best sensor format for a desired output
--
2.30.0