[Fix] Auto scale lr (#1584)

tools/train.py

@@ -90,15 +90,15 @@ def main():
     if args.resume:
         cfg.resume = True
 
+    # enable automatically scaling LR
     if args.auto_scale_lr:
-        if cfg.get('auto_scale_lr'):
-            cfg.auto_scale_lr = True
+        if 'auto_scale_lr' in cfg and \
+                'base_batch_size' in cfg.auto_scale_lr:
+            cfg.auto_scale_lr.enable = True
         else:
-            print_log(
-                'auto_scale_lr does not exist in your config, '
-                'please set `auto_scale_lr = dict(base_batch_size=xx)',
-                logger='current',
-                level=logging.WARNING)
+            raise RuntimeError('Can not find "auto_scale_lr" or '
+                               '"auto_scale_lr.base_batch_size" in your'
+                               ' configuration file.')
 
     # build the runner from config
     if 'runner_type' not in cfg: