libcamera: uvc: Report sensor timestamp

Report the sensor's timestamp in the Request metadata using the
completed buffer timestamp.

The UVC driver reports timestamps of SOE event through metadata, for
which there is no support in the current pipeline implementation.

Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Reviewed-by: Hirokazu Honda <hiroh@chromium.org>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>

src/libcamera/pipeline/uvcvideo/uvcvideo.cpp

@@ -662,6 +662,10 @@ void UVCCameraData::bufferReady(FrameBuffer *buffer)
 {
 	Request *request = buffer->request();
 
+	/* \todo Use the UVC metadata to calculate a more precise timestamp */
+	request->metadata().set(controls::SensorTimestamp,
+				buffer->metadata().timestamp);
+
 	pipe_->completeBuffer(request, buffer);
 	pipe_->completeRequest(request);
 }