ipa: simple: softisp: Extend to pass metadata

Extend the Simple IPA IPC to support returning a metadata ControlList
when the process call has completed.

A new signal from the IPA is introduced to report the metadata,
similarly to what the hardware pipelines do.

Merge the metadata reported by the ISP into any completing request to
provide to the application.  Completion of a request is delayed until
this is done; this doesn't apply to canceled requests.

Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Signed-off-by: Milan Zamazal <mzamazal@redhat.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

include/libcamera/internal/software_isp/software_isp.h

@@ -85,6 +85,7 @@ public:
 	Signal<FrameBuffer *> inputBufferReady;
 	Signal<FrameBuffer *> outputBufferReady;
 	Signal<uint32_t, uint32_t> ispStatsReady;
+	Signal<uint32_t, const ControlList &> metadataReady;
 	Signal<const ControlList &> setSensorControls;
 
 private:

include/libcamera/ipa/soft.mojom

@@ -33,4 +33,5 @@ interface IPASoftInterface {
 interface IPASoftEventInterface {
 	setSensorControls(libcamera.ControlList sensorControls);
 	setIspParams();
+	metadataReady(uint32 frame, libcamera.ControlList metadata);
 };