bugfix

src/lightning/fabric/strategies/ddp.py

@@ -78,7 +78,10 @@ def __init__(
         self._backward_sync_control = _DDPBackwardSyncControl()
         self._ddp_kwargs = kwargs
 
-        self.device_type = self.root_device.type
+        if isinstance(self.accelerator, Accelerator):
+            self.device_type = self.accelerator.get_device_type()
+        else:
+            self.device_type = "cuda"
         self.torch_lib = getattr(torch, self.device_type)
 
     @property

src/lightning/fabric/strategies/deepspeed.py

@@ -299,7 +299,10 @@ def __init__(
 
         self._deepspeed_engine: Optional[DeepSpeedEngine] = None
 
-        self.device_type = self.root_device.type
+        if isinstance(self.accelerator, Accelerator):
+            self.device_type = self.accelerator.get_device_type()
+        else:
+            self.device_type = "cuda"
         self.torch_lib = getattr(torch, self.device_type)
 
     @property

src/lightning/pytorch/strategies/ddp.py

@@ -103,8 +103,10 @@ def __init__(
         self._timeout: Optional[timedelta] = timeout
         self._start_method = start_method
 
-        self.device_type = self.root_device.type
-        self.torch_lib = getattr(torch, self.device_type)
+        try:
+            self.device_type = self.accelerator.get_device_type()
+        except Exception:
+            self.device_type = "cuda"
 
     @property
     def is_distributed(self) -> bool:  # pragma: no-cover

src/lightning/pytorch/strategies/deepspeed.py

@@ -319,7 +319,10 @@ def __init__(
         self.hysteresis = hysteresis
         self.min_loss_scale = min_loss_scale
 
-        self.device_type = self.root_device.type
+        try:
+            self.device_type = self.accelerator.get_device_type()
+        except Exception:
+            self.device_type = "cuda"
         self.torch_lib = getattr(torch, self.device_type)
 
     @override