[libcamera-devel] [PATCH v3 3/5] libcamera: raspberrypi: Set camera flips correctly from user transform

[David Plowman]

The Raspberry Pi pipeline handler allows all transforms except those
involving a transpose. The user transform is combined with any
inherent rotation of the camera, and the camera's H and V flip bits
are set accordingly.

Signed-off-by: David Plowman <david.plowman at raspberrypi.com>
---
 .../pipeline/raspberrypi/raspberrypi.cpp      | 34 ++++++++++++++++---
 1 file changed, 30 insertions(+), 4 deletions(-)

diff --git a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
index 236aa5c..a3f8438 100644
--- a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
+++ b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
@@ -324,6 +324,8 @@ public:
 	uint32_t expectedSequence_;
 	bool sensorMetadata_;
 
+	Transform transform_;
+
 	/*
 	 * All the functions in this class are called from a single calling
 	 * thread. So, we do not need to have any mutex to protect access to any
@@ -400,8 +402,27 @@ CameraConfiguration::Status RPiCameraConfiguration::validate()
 	if (config_.empty())
 		return Invalid;
 
-	if (transform != Transform::Identity) {
-		transform = Transform::Identity;
+	/*
+	 * What if the platform has a non-90 degree rotation? We can't even
+	 * "adjust" the configuration and carry on. Alternatively, raising an
+	 * error means the platform can never run. Let's just print a warning
+	 * and continue regardless; the rotation is effectively set to zero.
+	 */
+	int32_t rotation = data_->sensor_->properties().get(properties::Rotation);
+	bool success;
+	Transform combined = transform * transformFromRotation(rotation, &success);
+	if (!success)
+		LOG(RPI, Warning) << "Invalid rotation of " << rotation
+				  << " degrees - ignoring";
+
+	/*
+	 * We combine the platform and user transform, but must "adjust away"
+	 * any combined result that includes a transform, as we can't do those.
+	 * Flipping the transpose bit in either input transform causes the
+	 * corresponding bit in the combined result to flip.
+	 */
+	if (!!(combined & Transform::Transpose)) {
+		transform ^= Transform::Transpose;
 		status = Adjusted;
 	}
 
@@ -610,6 +631,9 @@ int PipelineHandlerRPi::configure(Camera *camera, CameraConfiguration *config)
 	for (auto const stream : data->streams_)
 		stream->reset();
 
+	/* We will want to know the transform requested by the application. */
+	data->transform_ = config->transform;
+
 	Size maxSize, sensorSize;
 	unsigned int maxIndex = 0;
 	bool rawStream = false;
@@ -1174,8 +1198,10 @@ int RPiCameraData::configureIPA()
 		/* Configure the H/V flip controls based on the sensor rotation. */
 		ControlList ctrls(unicam_[Unicam::Image].dev()->controls());
 		int32_t rotation = sensor_->properties().get(properties::Rotation);
-		ctrls.set(V4L2_CID_HFLIP, static_cast<int32_t>(!!rotation));
-		ctrls.set(V4L2_CID_VFLIP, static_cast<int32_t>(!!rotation));
+		/* The rotation was already checked in RPiCameraConfiguration::validate. */
+		Transform combined = transform_ * transformFromRotation(rotation);
+		ctrls.set(V4L2_CID_HFLIP, static_cast<int32_t>(!!(combined & Transform::HFlip)));
+		ctrls.set(V4L2_CID_VFLIP, static_cast<int32_t>(!!(combined & Transform::VFlip)));
 		unicam_[Unicam::Image].dev()->setControls(&ctrls);
 	}
 
-- 
2.20.1