[libcamera-devel] [PATCH 17/20] libcamera: pipeline: simple: Hardcode the number of internal buffers

[Laurent Pinchart]

The number of internal buffers, used between the capture device and the
converter, doesn't need to depend on the number of buffers allocated for
the output stream of the pipeline. Hardcode it to a fixed value.

Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
---
 src/libcamera/pipeline/simple/simple.cpp | 21 +++++++++++++++------
 1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/src/libcamera/pipeline/simple/simple.cpp b/src/libcamera/pipeline/simple/simple.cpp
index 9dffe64ee870..c987e1a0d9cb 100644
--- a/src/libcamera/pipeline/simple/simple.cpp
+++ b/src/libcamera/pipeline/simple/simple.cpp
@@ -228,6 +228,8 @@ protected:
 	int queueRequestDevice(Camera *camera, Request *request) override;
 
 private:
+	static constexpr unsigned int kNumInternalBuffers = 3;
+
 	SimpleCameraData *cameraData(const Camera *camera)
 	{
 		return static_cast<SimpleCameraData *>(
@@ -699,7 +701,7 @@ int SimplePipelineHandler::configure(Camera *camera, CameraConfiguration *c)
 		inputCfg.pixelFormat = pipeConfig->captureFormat;
 		inputCfg.size = pipeConfig->captureSize;
 		inputCfg.stride = captureFormat.planes[0].bpl;
-		inputCfg.bufferCount = cfg.bufferCount;
+		inputCfg.bufferCount = kNumInternalBuffers;
 
 		ret = converter_->configure(inputCfg, { cfg });
 		if (ret < 0) {
@@ -736,13 +738,20 @@ int SimplePipelineHandler::start(Camera *camera, [[maybe_unused]] ControlList *c
 {
 	SimpleCameraData *data = cameraData(camera);
 	V4L2VideoDevice *video = data->video_;
-	unsigned int count = data->streams_[0].configuration().bufferCount;
 	int ret;
 
-	if (data->useConverter_)
-		ret = video->allocateBuffers(count, &data->converterBuffers_);
-	else
-		ret = video->importBuffers(count);
+	if (data->useConverter_) {
+		/*
+		 * When using the converter allocate a fixed number of internal
+		 * buffers.
+		 */
+		ret = video->allocateBuffers(kNumInternalBuffers,
+					     &data->converterBuffers_);
+	} else {
+		/* Otherwise, prepare for using buffers from the only stream. */
+		Stream *stream = &data->streams_[0];
+		ret = video->importBuffers(stream->configuration().bufferCount);
+	}
 	if (ret < 0)
 		return ret;
 
-- 
Regards,

Laurent Pinchart