Fix dtype log when default (None) is used w/o AMP

Author: rwightman

train.py

@@ -597,7 +597,7 @@ def main():
             _logger.info('Using native Torch AMP. Training in mixed precision.')
     else:
         if utils.is_primary(args):
-            _logger.info(f'AMP not enabled. Training in {model_dtype}.')
+            _logger.info(f'AMP not enabled. Training in {model_dtype or torch.float32}.')
 
     # optionally resume from a checkpoint
     resume_epoch = None

validate.py

@@ -192,7 +192,7 @@ def validate(args):
             amp_autocast = partial(torch.autocast, device_type=device.type, dtype=amp_dtype)
             _logger.info('Validating in mixed precision with native PyTorch AMP.')
     else:
-        _logger.info(f'Validating in {model_dtype}. AMP not enabled.')
+        _logger.info(f'Validating in {model_dtype or torch.float32}. AMP not enabled.')
 
     if args.fuser:
         set_jit_fuser(args.fuser)