libcamera: pipeline_handler: Move waitingRequests_ into camera class

The waiting requests of one camera should not be able to influence
queuing to another camera. Currently a request that is in the
waitingQueue and waiting for preparation blocks all requests of other
cameras even if they are already prepared. To fix that replace the
single waitingRequests_ queue with one queue per camera.

Signed-off-by: Stefan Klug <stefan.klug@ideasonboard.com>
Reviewed-by: Umang Jain <uajain@igalia.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Tested-by: Sven Püschel <s.pueschel@pengutronix.de>

src/libcamera/camera.cpp

@@ -628,6 +628,15 @@ Camera::Private::~Private()
  * PipelineHandler::completeRequest()
  */
 
+/**
+ * \var Camera::Private::waitingRequests_
+ * \brief The queue of waiting requests
+ *
+ * This queue tracks all requests that can not yet be queued to the device.
+ * Either because they are not yet prepared or because the maximum number of
+ * queued requests was reached.
+ */
+
 /**
  * \var Camera::Private::controlInfo_
  * \brief The set of controls supported by the camera

src/libcamera/pipeline_handler.cpp

@@ -363,15 +363,16 @@ void PipelineHandler::stop(Camera *camera)
 	/* Stop the pipeline handler and let the queued requests complete. */
 	stopDevice(camera);
 
+	Camera::Private *data = camera->_d();
+
 	/* Cancel and signal as complete all waiting requests. */
-	while (!waitingRequests_.empty()) {
-		Request *request = waitingRequests_.front();
-		waitingRequests_.pop();
+	while (!data->waitingRequests_.empty()) {
+		Request *request = data->waitingRequests_.front();
+		data->waitingRequests_.pop();
 		cancelRequest(request);
 	}
 
 	/* Make sure no requests are pending. */
-	Camera::Private *data = camera->_d();
 	ASSERT(data->queuedRequests_.empty());
 
 	data->requestSequence_ = 0;
@@ -414,7 +415,9 @@ void PipelineHandler::registerRequest(Request *request)
 	 * Connect the request prepared signal to notify the pipeline handler
 	 * when a request is ready to be processed.
 	 */
-	request->_d()->prepared.connect(this, &PipelineHandler::doQueueRequests);
+	request->_d()->prepared.connect(this, [this, request]() {
+		doQueueRequests(request->_d()->camera());
+	});
 }
 
 /**
@@ -444,7 +447,9 @@ void PipelineHandler::queueRequest(Request *request)
 {
 	LIBCAMERA_TRACEPOINT(request_queue, request);
 
-	waitingRequests_.push(request);
+	Camera *camera = request->_d()->camera();
+	Camera::Private *data = camera->_d();
+	data->waitingRequests_.push(request);
 
 	request->_d()->prepare(300ms);
 }
@@ -478,15 +483,16 @@ void PipelineHandler::doQueueRequest(Request *request)
  * Iterate the list of waiting requests and queue them to the device one
  * by one if they have been prepared.
  */
-void PipelineHandler::doQueueRequests()
+void PipelineHandler::doQueueRequests(Camera *camera)
 {
-	while (!waitingRequests_.empty()) {
-		Request *request = waitingRequests_.front();
+	Camera::Private *data = camera->_d();
+	while (!data->waitingRequests_.empty()) {
+		Request *request = data->waitingRequests_.front();
 		if (!request->_d()->prepared_)
 			break;
 
 		doQueueRequest(request);
-		waitingRequests_.pop();
+		data->waitingRequests_.pop();
 	}
 }