[PATCH v2 1/2] libcamera: pipeline: Add function to clear acquired media devices

[Paul Elder]

Some pipeline handler implementations, such as the simple pipeline
handler, can encounter systems with multiple media devices that can be
supported.

In a subsequent patch, the simple pipeline handler will be updated so
that it will continue to match other media graphs even if the first
media graph it encounters has an invalid media device. In this case,
there would be a mix of invalid and valid media devices in
mediaDevices_.

Add a function to clear mediaDevices_ so that this can be
prevented.

Signed-off-by: Paul Elder <paul.elder at ideasonboard.com>
---
New in v2
---
 include/libcamera/internal/pipeline_handler.h |  2 ++
 src/libcamera/pipeline_handler.cpp            | 15 +++++++++++++++
 2 files changed, 17 insertions(+)

diff --git a/include/libcamera/internal/pipeline_handler.h b/include/libcamera/internal/pipeline_handler.h
index 972a2fa65310..5fa8bc2f66ee 100644
--- a/include/libcamera/internal/pipeline_handler.h
+++ b/include/libcamera/internal/pipeline_handler.h
@@ -71,6 +71,8 @@ public:
 	CameraManager *cameraManager() const { return manager_; }
 
 protected:
+	void clearMediaDevices();
+
 	void registerCamera(std::shared_ptr<Camera> camera);
 	void hotplugMediaDevice(MediaDevice *media);
 
diff --git a/src/libcamera/pipeline_handler.cpp b/src/libcamera/pipeline_handler.cpp
index d84dff3c9f19..8f12957b75fa 100644
--- a/src/libcamera/pipeline_handler.cpp
+++ b/src/libcamera/pipeline_handler.cpp
@@ -142,6 +142,21 @@ MediaDevice *PipelineHandler::acquireMediaDevice(DeviceEnumerator *enumerator,
 	return media.get();
 }
 
+/**
+ * \brief Clear the list of acquired media devices for this PipelineHandler instance
+ *
+ * This is meant to be used when the Pipeline Handler needs to search multiple
+ * media graphs to create multiple instances of itself, and a partial match
+ * needs to be canceled as an invalid media device was detected. This is to
+ * prevent mediaDevices_ from having a mix of invalid media devices from a
+ * previous failed match and valid media devices from the current succeeding
+ * match.
+ */
+void PipelineHandler::clearMediaDevices()
+{
+	mediaDevices_.clear();
+}
+
 /**
  * \brief Acquire exclusive access to the pipeline handler for the process
  *
-- 
2.47.2