[libcamera-devel] [PATCH] libcamera: camera_sensor: Adjust properties::Rotation

[Jacopo Mondi]

As the CameraSensor::validateTransform() function compensate
for the sensor's mounting rotation, the properties::Rotation value
should be adjusted to make sure application that receive already
"corrected" images do not get confused by Rotation still reporting
a value.

However, as an image sensor can only compensate rotations by applying
H/V flips, only correct Rotation when the mounting rotation is 180
degrees.

Signed-off-by: Jacopo Mondi <jacopo.mondi at ideasonboard.com>
---
 src/libcamera/camera.cpp        |  3 +--
 src/libcamera/camera_sensor.cpp | 21 ++++++++++++++++++---
 2 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/src/libcamera/camera.cpp b/src/libcamera/camera.cpp
index 99683e498697..3e252f3b8f8d 100644
--- a/src/libcamera/camera.cpp
+++ b/src/libcamera/camera.cpp
@@ -397,8 +397,7 @@ CameraConfiguration::Status CameraConfiguration::validateColorSpaces(ColorSpaceF
  *
  * The transform is a user-specified 2D plane transform that will be applied
  * to the camera images by the processing pipeline before being handed to
- * the application. This is subsequent to any transform that is already
- * required to fix up any platform-defined rotation.
+ * the application.
  *
  * The usual 2D plane transforms are allowed here (horizontal/vertical
  * flips, multiple of 90-degree rotations etc.), but the validate() function
diff --git a/src/libcamera/camera_sensor.cpp b/src/libcamera/camera_sensor.cpp
index 60bf87b49e6e..f3a5aa37149f 100644
--- a/src/libcamera/camera_sensor.cpp
+++ b/src/libcamera/camera_sensor.cpp
@@ -461,7 +461,17 @@ int CameraSensor::initProperties()

 	const auto &rotationControl = controls.find(V4L2_CID_CAMERA_SENSOR_ROTATION);
 	if (rotationControl != controls.end()) {
+		/*
+		 * validateTransform() compensates for the mounting rotation.
+		 * However, as a camera sensor can only compensate rotations
+		 * by applying H/VFlips, only rotation of 180 degrees are
+		 * automatically compensated. The other valid rotations (Rot90
+		 * and Rot270) require transposition, which the camera sensor
+		 * cannot perform, so leave them untouched.
+		 */
 		propertyValue = rotationControl->second.def().get<int32_t>();
+		if (propertyValue == 180 && supportFlips_)
+			propertyValue = 0;
 		properties_.set(properties::Rotation, propertyValue);
 	}

@@ -1028,10 +1038,15 @@ void CameraSensor::updateControlInfo()
  */
 Transform CameraSensor::validateTransform(Transform *transform) const
 {
-	/* Adjust the requested transform to compensate the sensor rotation. */
-	int32_t rotation = properties().get(properties::Rotation).value_or(0);
-	bool success;
+	/* Adjust the requested transform to compensate the sensor mounting rotation. */
+	const ControlInfoMap &controls = subdev_->controls();
+	int rotation = 0;

+	const auto &rotationControl = controls.find(V4L2_CID_CAMERA_SENSOR_ROTATION);
+	if (rotationControl != controls.end())
+		rotation = rotationControl->second.def().get<int32_t>();
+
+	bool success;
 	Transform rotationTransform = transformFromRotation(rotation, &success);
 	if (!success)
 		LOG(CameraSensor, Warning) << "Invalid rotation of " << rotation
--
2.40.1