[libcamera-devel] [PATCH v2 02/10] pipeline: raspberrypi: Add a pipeline config structure

[Naushir Patuck]

Add a configuration structure to store platform specific parameters used by
the pipeline handler. Currently, these only store Unicam buffer counts,
replacing the hardcoded static values in the source code.

In subsequent commits, more parameters will be added to the configuration
structure, and parameters will be read in through a config file.

Signed-off-by: Naushir Patuck <naush at raspberrypi.com>
Reviewed-by: David Plowman <david.plowman at raspberrypi.com>
---
 .../pipeline/raspberrypi/raspberrypi.cpp      | 51 ++++++++++++++++---
 1 file changed, 44 insertions(+), 7 deletions(-)

diff --git a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
index 0e0b71945640..4486d31ea78d 100644
--- a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
+++ b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
@@ -294,6 +294,21 @@ public:
 	/* Have internal buffers been allocated? */
 	bool buffersAllocated_;
 
+	struct Config {
+		/*
+		 * The minimum number of internal buffers to be allocated for
+		 * the Unicam Image stream.
+		 */
+		unsigned int minUnicamBuffers;
+		/*
+		 * The minimum total (internal + external) buffer count used for
+		 * the Unicam Image steram.
+		 */
+		unsigned int minTotalUnicamBuffers;
+	};
+
+	Config config_;
+
 private:
 	void checkRequestCompleted();
 	void fillRequestMetadata(const ControlList &bufferControls,
@@ -346,6 +361,7 @@ private:
 	}
 
 	int registerCamera(MediaDevice *unicam, MediaDevice *isp, MediaEntity *sensorEntity);
+	int configurePipelineHandler(RPiCameraData *data);
 	int queueAllBuffers(Camera *camera);
 	int prepareBuffers(Camera *camera);
 	void mapBuffers(Camera *camera, const RPi::BufferMap &buffers, unsigned int mask);
@@ -1377,6 +1393,12 @@ int PipelineHandlerRPi::registerCamera(MediaDevice *unicam, MediaDevice *isp, Me
 	streams.insert(&data->isp_[Isp::Output0]);
 	streams.insert(&data->isp_[Isp::Output1]);
 
+	int ret = configurePipelineHandler(data.get());
+	if (ret) {
+		LOG(RPI, Error) << "Unable to configure the pipeline handler!";
+		return ret;
+	}
+
 	/* Create and register the camera. */
 	const std::string &id = data->sensor_->id();
 	std::shared_ptr<Camera> camera =
@@ -1389,6 +1411,18 @@ int PipelineHandlerRPi::registerCamera(MediaDevice *unicam, MediaDevice *isp, Me
 	return 0;
 }
 
+int PipelineHandlerRPi::configurePipelineHandler(RPiCameraData *data)
+{
+	RPiCameraData::Config &config = data->config_;
+
+	config = {
+		.minUnicamBuffers = 2,
+		.minTotalUnicamBuffers = 4,
+	};
+
+	return 0;
+}
+
 int PipelineHandlerRPi::queueAllBuffers(Camera *camera)
 {
 	RPiCameraData *data = cameraData(camera);
@@ -1439,25 +1473,28 @@ int PipelineHandlerRPi::prepareBuffers(Camera *camera)
 	for (auto const stream : data->streams_) {
 		unsigned int numBuffers;
 		/*
-		 * For Unicam, allocate a minimum of 4 buffers as we want
-		 * to avoid any frame drops.
+		 * For Unicam, allocate a minimum number of buffers for internal
+		 * use as we want to avoid any frame drops.
 		 */
-		constexpr unsigned int minBuffers = 4;
+		const unsigned int minBuffers = data->config_.minTotalUnicamBuffers;
 		if (stream == &data->unicam_[Unicam::Image]) {
 			/*
 			 * If an application has configured a RAW stream, allocate
 			 * additional buffers to make up the minimum, but ensure
-			 * we have at least 2 sets of internal buffers to use to
-			 * minimise frame drops.
+			 * we have at least minUnicamBuffers sets of internal
+			 * buffers to use to minimise frame drops.
 			 */
-			numBuffers = std::max<int>(2, minBuffers - numRawBuffers);
+			numBuffers = std::max<int>(data->config_.minUnicamBuffers,
+						   minBuffers - numRawBuffers);
 		} else if (stream == &data->isp_[Isp::Input]) {
 			/*
 			 * ISP input buffers are imported from Unicam, so follow
 			 * similar logic as above to count all the RAW buffers
 			 * available.
 			 */
-			numBuffers = numRawBuffers + std::max<int>(2, minBuffers - numRawBuffers);
+			numBuffers = numRawBuffers +
+				     std::max<int>(data->config_.minUnicamBuffers,
+						   minBuffers - numRawBuffers);
 
 		} else if (stream == &data->unicam_[Unicam::Embedded]) {
 			/*
-- 
2.25.1