libcamera: pipeline: simple: Hardcode the number of internal buffers

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@ideasonboard.com>
Tested-by: Phi-Bang Nguyen <pnguyen@baylibre.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

1 files changed, 15 insertions, 6 deletions

diff --git a/src/libcamera/pipeline/simple/simple.cpp b/src/libcamera/pipeline/simple/simple.cpp
index 17fd744c..9f822397 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 *>(
@@ -700,7 +702,7 @@ 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) {
@@ -737,13 +739,20 @@ int SimplePipelineHandler::start(Camera *camera, [[maybe_unused]] const ControlL
 {
 	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;