libcamera: camera_sensor: Add parameter to limit returned sensor size

The getFormat function takes the aspect ratio and the area of the
requested size into account when choosing the best sensor size. In case
the sensor is connected to an rkisp1 the maximum supported frame size of
the ISP is another constraining factor for the selection of the best
format. Add a maxSize parameter to support such a constraint.

Signed-off-by: Stefan Klug <stefan.klug@ideasonboard.com>
Signed-off-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>

include/libcamera/internal/camera_sensor.h

@@ -53,7 +53,7 @@ public:
 
 	virtual V4L2SubdeviceFormat
 	getFormat(const std::vector<unsigned int> &mbusCodes,
-		  const Size &size) const = 0;
+		  const Size &size, const Size maxSize = Size()) const = 0;
 	virtual int setFormat(V4L2SubdeviceFormat *format,
 			      Transform transform = Transform::Identity) = 0;
 	virtual int tryFormat(V4L2SubdeviceFormat *format) const = 0;

src/libcamera/sensor/camera_sensor.cpp

@@ -116,6 +116,7 @@ CameraSensor::~CameraSensor() = default;
  * \brief Retrieve the best sensor format for a desired output
  * \param[in] mbusCodes The list of acceptable media bus codes
  * \param[in] size The desired size
+ * \param[in] maxSize The maximum size
  *
  * Media bus codes are selected from \a mbusCodes, which lists all acceptable
  * codes in decreasing order of preference. Media bus codes supported by the
@@ -134,6 +135,8 @@ CameraSensor::~CameraSensor() = default;
  *   bandwidth.
  * - The desired \a size shall be supported by one of the media bus code listed
  *   in \a mbusCodes.
+ * - The desired \a size shall fit into the maximum size \a maxSize if it is not
+ *   null.
  *
  * When multiple media bus codes can produce the same size, the code at the
  * lowest position in \a mbusCodes is selected.

src/libcamera/sensor/camera_sensor_legacy.cpp

@@ -74,7 +74,8 @@ public:
 	Size resolution() const override;
 
 	V4L2SubdeviceFormat getFormat(const std::vector<unsigned int> &mbusCodes,
-				      const Size &size) const override;
+				      const Size &size,
+				      const Size maxSize) const override;
 	int setFormat(V4L2SubdeviceFormat *format,
 		      Transform transform = Transform::Identity) override;
 	int tryFormat(V4L2SubdeviceFormat *format) const override;
@@ -699,7 +700,7 @@ Size CameraSensorLegacy::resolution() const
 
 V4L2SubdeviceFormat
 CameraSensorLegacy::getFormat(const std::vector<unsigned int> &mbusCodes,
-			      const Size &size) const
+			      const Size &size, Size maxSize) const
 {
 	unsigned int desiredArea = size.width * size.height;
 	unsigned int bestArea = UINT_MAX;
@@ -716,6 +717,10 @@ CameraSensorLegacy::getFormat(const std::vector<unsigned int> &mbusCodes,
 		for (const SizeRange &range : formats->second) {
 			const Size &sz = range.max;
 
+			if (!maxSize.isNull() &&
+			    (sz.width > maxSize.width || sz.height > maxSize.height))
+				continue;
+
 			if (sz.width < size.width || sz.height < size.height)
 				continue;