[libcamera-devel] [PATCH v2 3/4] ipu3: cio2: Change sensor size selection policy

[Umang Jain]

The current implementation of getSensorFormat() prioritizes sensor
sizes that match the output size FOV ratio.

Modify the frame size selection procedure to prioritize resolutions
with the same FOV as the sensor's native one, to avoid cropping in the
sensor pixel array.

For example:

- on a Soraka device equipped with ov13858 as back sensor, with a
  native resolution of 4224x3136 (4:3), when requested to select the
  sensor output size to produce 1080p (16:9) a frame size of 2112x1188
  (16:9) is selected causing the ImgU configuration procedure to fail.
  If a resolution with the same FOV as the sensor's native size, such
  as 2112x1568 (4:3), is selected the pipeline works correctly.

Suggested-by:: Jacopo Mondi <jacopo at jmondi.org>
Signed-off-by: Umang Jain <umang.jain at ideasonboard.com>
Tested-by: Umang Jain <umang.jain at ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo at jmondi.org>
Tested-by: Jacopo Mondi <jacopo at jmondi.org>
---
 src/libcamera/pipeline/ipu3/cio2.cpp | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/libcamera/pipeline/ipu3/cio2.cpp b/src/libcamera/pipeline/ipu3/cio2.cpp
index 88dd364b..3c9331e3 100644
--- a/src/libcamera/pipeline/ipu3/cio2.cpp
+++ b/src/libcamera/pipeline/ipu3/cio2.cpp
@@ -248,8 +248,8 @@ StreamConfiguration CIO2Device::generateConfiguration(Size size) const
  *
  * - The desired \a size shall fit in the sensor output size to avoid the need
  *   to up-scale.
- * - The sensor output size shall match the desired aspect ratio to avoid the
- *   need to crop the field of view.
+ * - The aspect ratio of sensor output size shall be as close as possible to
+ *   the sensor's native resolution field of view.
  * - The sensor output size shall be as small as possible to lower the required
  *   bandwidth.
  * - The desired \a size shall be supported by one of the media bus code listed
@@ -273,7 +273,9 @@ V4L2SubdeviceFormat CIO2Device::getSensorFormat(const std::vector<unsigned int>
 {
 	unsigned int desiredArea = size.width * size.height;
 	unsigned int bestArea = std::numeric_limits<unsigned int>::max();
-	float desiredRatio = static_cast<float>(size.width) / size.height;
+	const Size &resolution = sensor_->resolution();
+	float desiredRatio = static_cast<float>(resolution.width) /
+			     resolution.height;
 	float bestRatio = std::numeric_limits<float>::max();
 	Size bestSize;
 	uint32_t bestCode = 0;
-- 
2.31.1