libcamera: ipa: Pass a set of controls and return results from ipa::start()

This change allows controls passed into PipelineHandler::start to be
forwarded onto IPAInterface::start(). We also add a return channel if the
pipeline handler must action any of these controls, e.g. setting the
analogue gain or shutter speed in the sensor device.

The IPA interface wrapper isn't addressed as it will soon be replaced by
a new mechanism to handle IPC.

Signed-off-by: Naushir Patuck <naush@raspberrypi.com>
Reviewed-by: David Plowman <david.plowman@raspberrypi.com>
Tested-by: David Plowman <david.plowman@raspberrypi.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

src/libcamera/proxy/ipa_proxy_linux.cpp

@@ -30,7 +30,8 @@ public:
 	{
 		return 0;
 	}
-	int start() override { return 0; }
+	int start([[maybe_unused]] const IPAOperationData &data,
+		  [[maybe_unused]] IPAOperationData *result) override { return 0; }
 	void stop() override {}
 	void configure([[maybe_unused]] const CameraSensorInfo &sensorInfo,
 		       [[maybe_unused]] const std::map<unsigned int, IPAStream> &streamConfig,

src/libcamera/proxy/ipa_proxy_thread.cpp

@@ -26,7 +26,8 @@ public:
 	IPAProxyThread(IPAModule *ipam);
 
 	int init(const IPASettings &settings) override;
-	int start() override;
+	int start(const IPAOperationData &data,
+		  IPAOperationData *result) override;
 	void stop() override;
 
 	void configure(const CameraSensorInfo &sensorInfo,
@@ -50,9 +51,9 @@ private:
 			ipa_ = ipa;
 		}
 
-		int start()
+		int start(const IPAOperationData &data, IPAOperationData *result)
 		{
-			return ipa_->start();
+			return ipa_->start(data, result);
 		}
 
 		void stop()
@@ -111,12 +112,14 @@ int IPAProxyThread::init(const IPASettings &settings)
 	return 0;
 }
 
-int IPAProxyThread::start()
+int IPAProxyThread::start(const IPAOperationData &data,
+			  IPAOperationData *result)
 {
 	running_ = true;
 	thread_.start();
 
-	return proxy_.invokeMethod(&ThreadProxy::start, ConnectionTypeBlocking);
+	return proxy_.invokeMethod(&ThreadProxy::start, ConnectionTypeBlocking,
+				   data, result);
 }
 
 void IPAProxyThread::stop()