android: camera_stream: Create buffer pool

Add a FrameBufferAllocator class member to the CameraStream class.
The allocator is constructed for CameraStream instances that needs
internal allocation and automatically deleted.

Allocate FrameBuffers using the allocator_ class member in the
CameraStream class at CameraStream::configure() time and add two
methods to the CameraStream class to get and put FrameBuffer pointers
from the pool of allocated buffers. As buffer allocation can take place
only after the Camera has been configured, move the CameraStream
configuration loop in the CameraDevice class after camera_->configure()
call.

The newly created pool will be used to provide buffers to CameraStream
that need to provide memory to libcamera where to deliver frames.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>

3 files changed, 67 insertions, 11 deletions

diff --git a/src/android/camera_device.cpp b/src/android/camera_device.cpp
index 1e2cbeeb..ecdc0922 100644
--- a/src/android/camera_device.cpp
+++ b/src/android/camera_device.cpp
@@ -1283,6 +1283,17 @@ int CameraDevice::configureStreams(camera3_stream_configuration_t *stream_list)
 	}
 
 	/*
+	 * Once the CameraConfiguration has been adjusted/validated
+	 * it can be applied to the camera.
+	 */
+	int ret = camera_->configure(config_.get());
+	if (ret) {
+		LOG(HAL, Error) << "Failed to configure camera '"
+				<< camera_->id() << "'";
+		return ret;
+	}
+
+	/*
 	 * Configure the HAL CameraStream instances using the associated
 	 * StreamConfiguration and set the number of required buffers in
 	 * the Android camera3_stream_t.
@@ -1295,17 +1306,6 @@ int CameraDevice::configureStreams(camera3_stream_configuration_t *stream_list)
 		}
 	}
 
-	/*
-	 * Once the CameraConfiguration has been adjusted/validated
-	 * it can be applied to the camera.
-	 */
-	int ret = camera_->configure(config_.get());
-	if (ret) {
-		LOG(HAL, Error) << "Failed to configure camera '"
-				<< camera_->id() << "'";
-		return ret;
-	}
-
 	return 0;
 }
 
diff --git a/src/android/camera_stream.cpp b/src/android/camera_stream.cpp
index f899be4f..eac14805 100644
--- a/src/android/camera_stream.cpp
+++ b/src/android/camera_stream.cpp
@@ -26,6 +26,11 @@ CameraStream::CameraStream(CameraDevice *cameraDevice, Type type,
 
 	if (type_ == Type::Internal || type_ == Type::Mapped)
 		encoder_ = std::make_unique<EncoderLibJpeg>();
+
+	if (type == Type::Internal) {
+		allocator_ = std::make_unique<FrameBufferAllocator>(cameraDevice_->camera());
+		mutex_ = std::make_unique<std::mutex>();
+	}
 }
 
 const StreamConfiguration &CameraStream::configuration() const
@@ -46,6 +51,16 @@ int CameraStream::configure()
 			return ret;
 	}
 
+	if (allocator_) {
+		int ret = allocator_->allocate(stream());
+		if (ret < 0)
+			return ret;
+
+		/* Save a pointer to the reserved frame buffers */
+		for (const auto &frameBuffer : allocator_->buffers(stream()))
+			buffers_.push_back(frameBuffer.get());
+	}
+
 	camera3Stream_->max_buffers = configuration().bufferCount;
 
 	return 0;
@@ -109,3 +124,31 @@ int CameraStream::process(const libcamera::FrameBuffer &source,
 
 	return 0;
 }
+
+FrameBuffer *CameraStream::getBuffer()
+{
+	if (!allocator_)
+		return nullptr;
+
+	std::lock_guard<std::mutex> locker(*mutex_);
+
+	if (buffers_.empty()) {
+		LOG(HAL, Error) << "Buffer underrun";
+		return nullptr;
+	}
+
+	FrameBuffer *buffer = buffers_.back();
+	buffers_.pop_back();
+
+	return buffer;
+}
+
+void CameraStream::putBuffer(libcamera::FrameBuffer *buffer)
+{
+	if (!allocator_)
+		return;
+
+	std::lock_guard<std::mutex> locker(*mutex_);
+
+	buffers_.push_back(buffer);
+}
diff --git a/src/android/camera_stream.h b/src/android/camera_stream.h
index 4c51f0fb..8df0101c 100644
--- a/src/android/camera_stream.h
+++ b/src/android/camera_stream.h
@@ -8,11 +8,14 @@
 #define __ANDROID_CAMERA_STREAM_H__
 
 #include <memory>
+#include <mutex>
+#include <vector>
 
 #include <hardware/camera3.h>
 
 #include <libcamera/buffer.h>
 #include <libcamera/camera.h>
+#include <libcamera/framebuffer_allocator.h>
 #include <libcamera/geometry.h>
 #include <libcamera/pixel_format.h>
 
@@ -117,6 +120,8 @@ public:
 	int configure();
 	int process(const libcamera::FrameBuffer &source,
 		    MappedCamera3Buffer *dest, CameraMetadata *metadata);
+	libcamera::FrameBuffer *getBuffer();
+	void putBuffer(libcamera::FrameBuffer *buffer);
 
 private:
 	CameraDevice *cameraDevice_;
@@ -129,7 +134,15 @@ private:
 	 * one or more streams to the Android framework.
 	 */
 	unsigned int index_;
+
 	std::unique_ptr<Encoder> encoder_;
+	std::unique_ptr<libcamera::FrameBufferAllocator> allocator_;
+	std::vector<libcamera::FrameBuffer *> buffers_;
+	/*
+	 * The class has to be MoveConstructible as instances are stored in
+	 * an std::vector in CameraDevice.
+	 */
+	 std::unique_ptr<std::mutex> mutex_;
 };
 
 #endif /* __ANDROID_CAMERA_STREAM__ */