diff --git a/src/libcamera/software_isp/debayer.cpp b/src/libcamera/software_isp/debayer.cpp
index 1d135b278..32a2c8378 100644
--- a/src/libcamera/software_isp/debayer.cpp
+++ b/src/libcamera/software_isp/debayer.cpp
@@ -336,6 +336,24 @@ Debayer::~Debayer()
  * debayer processing.
  */
 
+/**
+ * \fn int Debayer::start()
+ * \brief Execute a start signal in the debayer object from workerthread context.
+ *
+ * In the DebayerCPU case this is an empty stub function but
+ * for the GPU case this does something useful. The stub here is to
+ * ensure the right version of the virtual gets called.
+ */
+
+/**
+ * \fn void Debayer::stop()
+ * \brief Stop the debayering process and perform cleanup
+ *
+ * In the DebayerCPU case this is an empty stub function but
+ * for the GPU case this does something useful. The stub here is to
+ * ensure the right version of the virtual gets called.
+ */
+
 /**
  * \fn void Debayer::setParams(DebayerParams &params)
  * \brief Select the bayer params to use for the next frame debayer
diff --git a/src/libcamera/software_isp/debayer.h b/src/libcamera/software_isp/debayer.h
index ff4a92c15..5c0cb3914 100644
--- a/src/libcamera/software_isp/debayer.h
+++ b/src/libcamera/software_isp/debayer.h
@@ -48,6 +48,8 @@ public:
 	strideAndFrameSize(const PixelFormat &outputFormat, const Size &size) = 0;
 
 	virtual void process(uint32_t frame, FrameBuffer *input, FrameBuffer *output, DebayerParams params) = 0;
+	virtual int start() { return 0; }
+	virtual void stop() { }
 
 	virtual SizeRange sizes(PixelFormat inputFormat, const Size &inputSize) = 0;
 
diff --git a/src/libcamera/software_isp/software_isp.cpp b/src/libcamera/software_isp/software_isp.cpp
index 928a2520c..7c9ad9160 100644
--- a/src/libcamera/software_isp/software_isp.cpp
+++ b/src/libcamera/software_isp/software_isp.cpp
@@ -347,7 +347,9 @@ int SoftwareIsp::start()
 		return ret;
 
 	ispWorkerThread_.start();
-	return 0;
+
+	return debayer_->invokeMethod(&DebayerCpu::start,
+				      ConnectionTypeBlocking);
 }
 
 /**
@@ -358,9 +360,11 @@ int SoftwareIsp::start()
  */
 void SoftwareIsp::stop()
 {
+	debayer_->invokeMethod(&DebayerCpu::stop,
+			       ConnectionTypeBlocking);
+
 	ispWorkerThread_.exit();
 	ispWorkerThread_.wait();
-	ispWorkerThread_.removeMessages(debayer_.get());
 
 	Thread::current()->dispatchMessages(Message::Type::InvokeMessage, this);