libcamera: framebuffer: Add Fence to FrameBuffer

Add to the FrameBuffer::Private class a unique pointer to a
Fence.

The Fence will be used to signal the availability of the Framebuffer for
incoming data transfer.

The Fence will be associated to a FrameBuffer at Request::addBuffer()
time, and if correctly signalled, reset by the core at Request queue
time.

If a FrameBuffer completes with errors, due to a Fence wait failure, the
Fence will still be owned by the FrameBuffer and it is application
responsibility to correctly reset it before reusing the buffer.

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

include/libcamera/framebuffer.h

@@ -9,6 +9,7 @@
 
 #include <assert.h>
 #include <limits>
+#include <memory>
 #include <stdint.h>
 #include <vector>
 
@@ -18,6 +19,7 @@
 
 namespace libcamera {
 
+class Fence;
 class Request;
 
 struct FrameMetadata {
@@ -67,6 +69,8 @@ public:
 	unsigned int cookie() const { return cookie_; }
 	void setCookie(unsigned int cookie) { cookie_ = cookie; }
 
+	std::unique_ptr<Fence> releaseFence();
+
 	void cancel() { metadata_.status = FrameMetadata::FrameCancelled; }
 
 private:

include/libcamera/internal/framebuffer.h

@@ -7,8 +7,12 @@
 
 #pragma once
 
+#include <memory>
+#include <utility>
+
 #include <libcamera/base/class.h>
 
+#include <libcamera/fence.h>
 #include <libcamera/framebuffer.h>
 
 namespace libcamera {
@@ -24,7 +28,11 @@ public:
 	void setRequest(Request *request) { request_ = request; }
 	bool isContiguous() const { return isContiguous_; }
 
+	Fence *fence() const { return fence_.get(); }
+	void setFence(std::unique_ptr<Fence> fence) { fence_ = std::move(fence); }
+
 private:
+	std::unique_ptr<Fence> fence_;
 	Request *request_;
 	bool isContiguous_;
 };