From e4edcf55ba4d5254973137107ae2b376f7635f45 Mon Sep 17 00:00:00 2001
From: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
Date: Fri, 11 Oct 2024 10:24:58 +0200
Subject: rkisp1_path: Allow to pre-queue video buffers

In order to pre-queue video buffers, the memory management mode of the
video device should be switched to DMABUF and the buffer cache needs to
be initialized. This is done by the V4L2VideoDevice::importBuffers()
function.

Currently the RkISP1Path class calls importBuffers() in its start()
function, preventing buffer pre-queueing before starting the video
device.

Break out the buffer import operation to a pre-queue buffer function
to allow buffer pre-queueing.

Signed-off-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
---
 src/libcamera/pipeline/rkisp1/rkisp1_path.cpp | 30 ++++++++++++++++++++++-----
 src/libcamera/pipeline/rkisp1/rkisp1_path.h   |  2 ++
 2 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/src/libcamera/pipeline/rkisp1/rkisp1_path.cpp b/src/libcamera/pipeline/rkisp1/rkisp1_path.cpp
index 1999094e..3ce059a2 100644
--- a/src/libcamera/pipeline/rkisp1/rkisp1_path.cpp
+++ b/src/libcamera/pipeline/rkisp1/rkisp1_path.cpp
@@ -474,6 +474,31 @@ int RkISP1Path::configure(const StreamConfiguration &config,
 	return 0;
 }
 
+/*
+ * NOTE: the 'buffers' will be empty after calling this function.
+ */
+int RkISP1Path::preQueueBuffers(std::deque<FrameBuffer *> &buffers)
+{
+	/* \todo Make buffer count user configurable. */
+	int ret = video_->importBuffers(RKISP1_BUFFER_COUNT);
+	if (ret)
+		return ret;
+
+	/* Pre-queue buffers in the video output. */
+	while (!buffers.empty()) {
+		auto buf = buffers.front();
+		buffers.pop_front();
+
+		ret = video_->queueBuffer(buf);
+		if (ret) {
+			LOG(RkISP1, Error) << "Failed to pre-queue capture buffers";
+			return ret;
+		}
+	}
+
+	return 0;
+}
+
 int RkISP1Path::start()
 {
 	int ret;
@@ -481,11 +506,6 @@ int RkISP1Path::start()
 	if (running_)
 		return -EBUSY;
 
-	/* \todo Make buffer count user configurable. */
-	ret = video_->importBuffers(RKISP1_BUFFER_COUNT);
-	if (ret)
-		return ret;
-
 	ret = video_->streamOn();
 	if (ret) {
 		LOG(RkISP1, Error)
diff --git a/src/libcamera/pipeline/rkisp1/rkisp1_path.h b/src/libcamera/pipeline/rkisp1/rkisp1_path.h
index ce9a5666..4ec7ce5c 100644
--- a/src/libcamera/pipeline/rkisp1/rkisp1_path.h
+++ b/src/libcamera/pipeline/rkisp1/rkisp1_path.h
@@ -7,6 +7,7 @@
 
 #pragma once
 
+#include <deque>
 #include <map>
 #include <memory>
 #include <set>
@@ -57,6 +58,7 @@ public:
 		return video_->exportBuffers(bufferCount, buffers);
 	}
 
+	int preQueueBuffers(std::deque<FrameBuffer *> &buffers);
 	int start();
 	void stop();
 
-- 
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