diff --git a/bitsandbytes/functional.py b/bitsandbytes/functional.py
index a76aadb73..2b4a1e246 100644
--- a/bitsandbytes/functional.py
+++ b/bitsandbytes/functional.py
@@ -1067,7 +1067,7 @@ def dequantize_fp4(
     quant_state: Optional[QuantState] = None,
     absmax: Optional[torch.Tensor] = None,
     out: Optional[torch.Tensor] = None,
-    blocksize: int = 64,
+    blocksize: Optional[int] = None,
 ) -> torch.Tensor:
     return dequantize_4bit(A, quant_state, absmax, out, blocksize, "fp4")
 
@@ -1077,7 +1077,7 @@ def dequantize_nf4(
     quant_state: Optional[QuantState] = None,
     absmax: Optional[torch.Tensor] = None,
     out: Optional[torch.Tensor] = None,
-    blocksize: int = 64,
+    blocksize: Optional[int] = None,
 ) -> torch.Tensor:
     return dequantize_4bit(A, quant_state, absmax, out, blocksize, "nf4")
 
@@ -1087,8 +1087,8 @@ def dequantize_4bit(
     quant_state: Optional[QuantState] = None,
     absmax: Optional[torch.Tensor] = None,
     out: Optional[torch.Tensor] = None,
-    blocksize: int = 64,
-    quant_type="fp4",
+    blocksize: Optional[int] = None,
+    quant_type: Optional[str] = "fp4",
 ) -> torch.Tensor:
     """Dequantizes a packed 4-bit quantized tensor.
 
@@ -1106,9 +1106,9 @@ def dequantize_4bit(
             Required if `quant_state` is not provided and ignored otherwise.
         out (`torch.Tensor`, *optional*): A tensor to use to store the result.
         blocksize (`int`, *optional*):
-            The size of the blocks. Defaults to 64.
+            The size of the blocks. Defaults to 64 if not HIP_ENVIRONMENT else 128.
             Valid values are 64, 128, 256, 512, 1024, 2048, and 4096.
-        quant_type (`str`, *optional*): The data type to use: `nf4` or `fp4`. Defaults to `fp4`.
+        quant_type (`str`, *optional*): The data type to use: `nf4` or `fp4`. Defaults to "fp4".
 
     Raises:
         ValueError: Raised when the input data type or blocksize is not supported.
@@ -1118,9 +1118,9 @@ def dequantize_4bit(
     """
     ensure_backend_is_available(A.device.type)
     if quant_state is not None:
-        absmax = absmax or quant_state.absmax
-        quant_type = quant_type or quant_state.quant_type
-        blocksize = blocksize or quant_state.blocksize
+        absmax = quant_state.absmax
+        quant_type = quant_state.quant_type
+        blocksize = quant_state.blocksize
     if blocksize is None:
         # Some AMD GPUs have warpsize 64
         # Set default blocksize to 128 (~warpsize 64 in kernel) for HIP
diff --git a/bitsandbytes/nn/modules.py b/bitsandbytes/nn/modules.py
index 0ea82575a..961f746ba 100755
--- a/bitsandbytes/nn/modules.py
+++ b/bitsandbytes/nn/modules.py
@@ -487,6 +487,7 @@ def _save_to_state_dict(self, destination, prefix, keep_vars):
                 self.weight.data = reverse_4bit_compress_format(self.weight.data.reshape(1, -1))
 
             self.weight.quant_state.ipex = False
+            self.ipex_linear_is_set = False
 
         super()._save_to_state_dict(destination, prefix, keep_vars)  # saving weight and bias
 
@@ -496,15 +497,13 @@ def _save_to_state_dict(self, destination, prefix, keep_vars):
 
     def set_ipex_linear(self, x: torch.Tensor):
         if (
-            (x.device.type in ("cpu", "xpu"))
-            and not getattr(self.weight.quant_state, "ipex", False)
+            not getattr(self.weight.quant_state, "ipex", False)
             and self.weight.data.dtype == torch.uint8
             and self.weight.quant_state.shape[1] % self.weight.quant_state.blocksize == 0
             and self.weight.quant_state.quant_type == "nf4"
-            and not self.training
-            and x.requires_grad == False
         ):
-            enable_ipex_fusion(self, x)
+            if x.device.type == "xpu" or (x.device.type == "cpu" and not self.training and x.requires_grad == False):
+                enable_ipex_fusion(self, x)
 
     def forward(self, x: torch.Tensor):
         # Check if ipex fusion can be used
@@ -695,7 +694,7 @@ def to(self: T, tensor: Tensor, non_blocking: bool = ...) -> T: ...
     def to(self, *args, **kwargs):
         device, dtype, non_blocking, convert_to_format = torch._C._nn._parse_to(*args, **kwargs)
 
-        if device in ("cuda", "xpu", "cpu"):
+        if device is not None and device.type in ("cuda", "xpu", "cpu"):
             if device.type == "cuda" and self.data.device.type == "cpu":
                 return self.cuda(device)
             elif device.type == "cpu":