libcamera: camera: Reset request sequence number on stop/start

We now have V4L2VideoDevice ensuring that sensor sequence numbers
start from zero [1], and we desire that these should match the Request
sequence number as well.

[1] 1c9dc0fd89 ("libcamera: v4l2_videodevice: Identify non-zero stream starts")

Signed-off-by: Umang Jain <umang.jain@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

src/libcamera/camera.cpp

@@ -497,7 +497,7 @@ Camera::Private::~Private()
  * facilitate debugging of internal request usage.
  *
  * The requestSequence_ tracks the number of requests queued to a camera
- * over its lifetime.
+ * over a single capture session.
  */
 
 static const char *const camera_state_names[] = {
@@ -1181,6 +1181,8 @@ int Camera::start(const ControlList *controls)
 
 	LOG(Camera, Debug) << "Starting capture";
 
+	ASSERT(d->requestSequence_ == 0);
+
 	ret = d->pipe_->invokeMethod(&PipelineHandler::start,
 				     ConnectionTypeBlocking, this, controls);
 	if (ret)