switch to the proper way of calling xformers

modules/sd_hijack_optimizations.py

@@ -94,39 +94,17 @@ def split_cross_attention_forward(self, x, context=None, mask=None):
 
     return self.to_out(r2)
 
-def _maybe_init(self, x):
-    """
-    Initialize the attention operator, if required We expect the head dimension to be exposed here, meaning that x
-    : B, Head, Length
-    """
-    if self.attention_op is not None:
-        return
-    _, M, K = x.shape
-    try:
-        self.attention_op = xformers.ops.AttentionOpDispatch(
-            dtype=x.dtype,
-            device=x.device,
-            k=K,
-            attn_bias_type=type(None),
-            has_dropout=False,
-            kv_len=M,
-            q_len=M,
-        ).op
-    except NotImplementedError as err:
-        raise NotImplementedError(f"Please install xformers with the flash attention / cutlass components.\n{err}")
-
 def xformers_attention_forward(self, x, context=None, mask=None):
     h = self.heads
     q_in = self.to_q(x)
     context = default(context, x)
     k_in = self.to_k(context)
     v_in = self.to_v(context)
-    q, k, v = map(lambda t: rearrange(t, 'b n (h d) -> (b h) n d', h=h), (q_in, k_in, v_in))
+    q, k, v = map(lambda t: rearrange(t, 'b n (h d) -> b n h d', h=h), (q_in, k_in, v_in))
     del q_in, k_in, v_in
-    self._maybe_init(q)
-    out = xformers.ops.memory_efficient_attention(q, k, v, attn_bias=None, op=self.attention_op)
+    out = xformers.ops.memory_efficient_attention(q, k, v, attn_bias=None)
 
-    out = rearrange(out, '(b h) n d -> b n (h d)', h=h)
+    out = rearrange(out, 'b n h d -> b n (h d)', h=h)
     return self.to_out(out)
 
 def cross_attention_attnblock_forward(self, x):