refactor(config): Move device & amp args to PreTrainedConfig (#812)

Co-authored-by: Simon Alibert <75076266+aliberts@users.noreply.github.com>

lerobot/scripts/train.py

@@ -120,7 +120,7 @@ def train(cfg: TrainPipelineConfig):
         set_seed(cfg.seed)
 
     # Check device is available
-    device = get_safe_torch_device(cfg.device, log=True)
+    device = get_safe_torch_device(cfg.policy.device, log=True)
     torch.backends.cudnn.benchmark = True
     torch.backends.cuda.matmul.allow_tf32 = True
 
@@ -138,13 +138,12 @@ def train(cfg: TrainPipelineConfig):
     logging.info("Creating policy")
     policy = make_policy(
         cfg=cfg.policy,
-        device=device,
         ds_meta=dataset.meta,
     )
 
     logging.info("Creating optimizer and scheduler")
     optimizer, lr_scheduler = make_optimizer_and_scheduler(cfg, policy)
-    grad_scaler = GradScaler(device, enabled=cfg.use_amp)
+    grad_scaler = GradScaler(device.type, enabled=cfg.policy.use_amp)
 
     step = 0  # number of policy updates (forward + backward + optim)
 
@@ -218,7 +217,7 @@ def train(cfg: TrainPipelineConfig):
             cfg.optimizer.grad_clip_norm,
             grad_scaler=grad_scaler,
             lr_scheduler=lr_scheduler,
-            use_amp=cfg.use_amp,
+            use_amp=cfg.policy.use_amp,
         )
 
         # Note: eval and checkpoint happens *after* the `step`th training update has completed, so we
@@ -249,7 +248,10 @@ def train(cfg: TrainPipelineConfig):
         if cfg.env and is_eval_step:
             step_id = get_step_identifier(step, cfg.steps)
             logging.info(f"Eval policy at step {step}")
-            with torch.no_grad(), torch.autocast(device_type=device.type) if cfg.use_amp else nullcontext():
+            with (
+                torch.no_grad(),
+                torch.autocast(device_type=device.type) if cfg.policy.use_amp else nullcontext(),
+            ):
                 eval_info = eval_policy(
                     eval_env,
                     policy,