cam: Cache buffer memory mapping

With the buffer allocator in use it's possible to cache the dmabuf
memory mappings when starting the camera instead of mapping and
unmapping them each time.

Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

3 files changed, 30 insertions, 5 deletions

diff --git a/src/cam/buffer_writer.cpp b/src/cam/buffer_writer.cpp
index 1d7366c8..c5a5eb46 100644
--- a/src/cam/buffer_writer.cpp
+++ b/src/cam/buffer_writer.cpp
@@ -22,6 +22,27 @@ BufferWriter::BufferWriter(const std::string &pattern)
 {
 }
 
+BufferWriter::~BufferWriter()
+{
+	for (auto &iter : mappedBuffers_) {
+		void *memory = iter.second.first;
+		unsigned int length = iter.second.second;
+		munmap(memory, length);
+	}
+	mappedBuffers_.clear();
+}
+
+void BufferWriter::mapBuffer(FrameBuffer *buffer)
+{
+	for (const FrameBuffer::Plane &plane : buffer->planes()) {
+		void *memory = mmap(NULL, plane.length, PROT_READ, MAP_SHARED,
+				    plane.fd.fd(), 0);
+
+		mappedBuffers_[plane.fd.fd()] =
+			std::make_pair(memory, plane.length);
+	}
+}
+
 int BufferWriter::write(FrameBuffer *buffer, const std::string &streamName)
 {
 	std::string filename;
@@ -44,9 +65,7 @@ int BufferWriter::write(FrameBuffer *buffer, const std::string &streamName)
 		return -errno;
 
 	for (const FrameBuffer::Plane &plane : buffer->planes()) {
-		/* \todo Once the FrameBuffer is done cache mapped memory. */
-		void *data = mmap(NULL, plane.length, PROT_READ, MAP_SHARED,
-				  plane.fd.fd(), 0);
+		void *data = mappedBuffers_[plane.fd.fd()].first;
 		unsigned int length = plane.length;
 
 		ret = ::write(fd, data, length);
@@ -61,8 +80,6 @@ int BufferWriter::write(FrameBuffer *buffer, const std::string &streamName)
 				  << length << std::endl;
 			break;
 		}
-
-		munmap(data, length);
 	}
 
 	close(fd);
diff --git a/src/cam/buffer_writer.h b/src/cam/buffer_writer.h
index 5917a7df..8c9b2436 100644
--- a/src/cam/buffer_writer.h
+++ b/src/cam/buffer_writer.h
@@ -7,6 +7,7 @@
 #ifndef __LIBCAMERA_BUFFER_WRITER_H__
 #define __LIBCAMERA_BUFFER_WRITER_H__
 
+#include <map>
 #include <string>
 
 #include <libcamera/buffer.h>
@@ -15,12 +16,16 @@ class BufferWriter
 {
 public:
 	BufferWriter(const std::string &pattern = "frame-#.bin");
+	~BufferWriter();
+
+	void mapBuffer(libcamera::FrameBuffer *buffer);
 
 	int write(libcamera::FrameBuffer *buffer,
 		  const std::string &streamName);
 
 private:
 	std::string pattern_;
+	std::map<int, std::pair<void *, unsigned int>> mappedBuffers_;
 };
 
 #endif /* __LIBCAMERA_BUFFER_WRITER_H__ */
diff --git a/src/cam/capture.cpp b/src/cam/capture.cpp
index dd078eb0..738fa1c2 100644
--- a/src/cam/capture.cpp
+++ b/src/cam/capture.cpp
@@ -116,6 +116,9 @@ int Capture::capture(EventLoop *loop, FrameBufferAllocator *allocator)
 					  << std::endl;
 				return ret;
 			}
+
+			if (writer_)
+				writer_->mapBuffer(buffer.get());
 		}
 
 		requests.push_back(request);