text: Title: 'function' object has no attribute 'parameters' when I start to train the backbone in the 10 epoch
  Body: start training backbone.
  Traceback (most recent call last):
    File "../../tools/train.py", line 322, in <module>
      main()
    File "../../tools/train.py", line 317, in main
      train(train_loader, dist_model, optimizer, lr_scheduler, tb_writer)
    File "../../tools/train.py", line 194, in train
      optimizer, lr_scheduler = build_opt_lr(model.module, epoch)
    File "../../tools/train.py", line 77, in build_opt_lr
      for param in getattr(model.backbone, layer).parameters():
  AttributeError: 'function' object has no attribute 'parameters'
  
  How can I deal with it?