[WIP][LoRA] start supporting kijai wan lora. (#11579)

* start supporting kijai wan lora.

* diff_b keys.

* Apply suggestions from code review

Co-authored-by: Aryan <aryan@huggingface.co>

* merge ready

---------

Co-authored-by: Aryan <aryan@huggingface.co>

Author: sayakpaul

src/diffusers/loaders/lora_conversion_utils.py

@@ -1596,48 +1596,131 @@ def _convert_non_diffusers_wan_lora_to_diffusers(state_dict):
     converted_state_dict = {}
     original_state_dict = {k[len("diffusion_model.") :]: v for k, v in state_dict.items()}
 
-    num_blocks = len({k.split("blocks.")[1].split(".")[0] for k in original_state_dict})
+    num_blocks = len({k.split("blocks.")[1].split(".")[0] for k in original_state_dict if "blocks." in k})
     is_i2v_lora = any("k_img" in k for k in original_state_dict) and any("v_img" in k for k in original_state_dict)
+    lora_down_key = "lora_A" if any("lora_A" in k for k in original_state_dict) else "lora_down"
+    lora_up_key = "lora_B" if any("lora_B" in k for k in original_state_dict) else "lora_up"
+
+    diff_keys = [k for k in original_state_dict if k.endswith((".diff_b", ".diff"))]
+    if diff_keys:
+        for diff_k in diff_keys:
+            param = original_state_dict[diff_k]
+            all_zero = torch.all(param == 0).item()
+            if all_zero:
+                logger.debug(f"Removed {diff_k} key from the state dict as it's all zeros.")
+                original_state_dict.pop(diff_k)
+
+    # For the `diff_b` keys, we treat them as lora_bias.
+    # https://huggingface.co/docs/peft/main/en/package_reference/lora#peft.LoraConfig.lora_bias
 
     for i in range(num_blocks):
         # Self-attention
         for o, c in zip(["q", "k", "v", "o"], ["to_q", "to_k", "to_v", "to_out.0"]):
             converted_state_dict[f"blocks.{i}.attn1.{c}.lora_A.weight"] = original_state_dict.pop(
-                f"blocks.{i}.self_attn.{o}.lora_A.weight"
+                f"blocks.{i}.self_attn.{o}.{lora_down_key}.weight"
             )
             converted_state_dict[f"blocks.{i}.attn1.{c}.lora_B.weight"] = original_state_dict.pop(
-                f"blocks.{i}.self_attn.{o}.lora_B.weight"
+                f"blocks.{i}.self_attn.{o}.{lora_up_key}.weight"
             )
+            if f"blocks.{i}.self_attn.{o}.diff_b" in original_state_dict:
+                converted_state_dict[f"blocks.{i}.attn1.{c}.lora_B.bias"] = original_state_dict.pop(
+                    f"blocks.{i}.self_attn.{o}.diff_b"
+                )
 
         # Cross-attention
         for o, c in zip(["q", "k", "v", "o"], ["to_q", "to_k", "to_v", "to_out.0"]):
             converted_state_dict[f"blocks.{i}.attn2.{c}.lora_A.weight"] = original_state_dict.pop(
-                f"blocks.{i}.cross_attn.{o}.lora_A.weight"
+                f"blocks.{i}.cross_attn.{o}.{lora_down_key}.weight"
             )
             converted_state_dict[f"blocks.{i}.attn2.{c}.lora_B.weight"] = original_state_dict.pop(
-                f"blocks.{i}.cross_attn.{o}.lora_B.weight"
+                f"blocks.{i}.cross_attn.{o}.{lora_up_key}.weight"
             )
+            if f"blocks.{i}.cross_attn.{o}.diff_b" in original_state_dict:
+                converted_state_dict[f"blocks.{i}.attn2.{c}.lora_B.bias"] = original_state_dict.pop(
+                    f"blocks.{i}.cross_attn.{o}.diff_b"
+                )
 
         if is_i2v_lora:
             for o, c in zip(["k_img", "v_img"], ["add_k_proj", "add_v_proj"]):
                 converted_state_dict[f"blocks.{i}.attn2.{c}.lora_A.weight"] = original_state_dict.pop(
-                    f"blocks.{i}.cross_attn.{o}.lora_A.weight"
+                    f"blocks.{i}.cross_attn.{o}.{lora_down_key}.weight"
                 )
                 converted_state_dict[f"blocks.{i}.attn2.{c}.lora_B.weight"] = original_state_dict.pop(
-                    f"blocks.{i}.cross_attn.{o}.lora_B.weight"
+                    f"blocks.{i}.cross_attn.{o}.{lora_up_key}.weight"
                 )
+                if f"blocks.{i}.cross_attn.{o}.diff_b" in original_state_dict:
+                    converted_state_dict[f"blocks.{i}.attn2.{c}.lora_B.bias"] = original_state_dict.pop(
+                        f"blocks.{i}.cross_attn.{o}.diff_b"
+                    )
 
         # FFN
         for o, c in zip(["ffn.0", "ffn.2"], ["net.0.proj", "net.2"]):
             converted_state_dict[f"blocks.{i}.ffn.{c}.lora_A.weight"] = original_state_dict.pop(
-                f"blocks.{i}.{o}.lora_A.weight"
+                f"blocks.{i}.{o}.{lora_down_key}.weight"
             )
             converted_state_dict[f"blocks.{i}.ffn.{c}.lora_B.weight"] = original_state_dict.pop(
-                f"blocks.{i}.{o}.lora_B.weight"
+                f"blocks.{i}.{o}.{lora_up_key}.weight"
             )
+            if f"blocks.{i}.{o}.diff_b" in original_state_dict:
+                converted_state_dict[f"blocks.{i}.ffn.{c}.lora_B.bias"] = original_state_dict.pop(
+                    f"blocks.{i}.{o}.diff_b"
+                )
+
+    # Remaining.
+    if original_state_dict:
+        if any("time_projection" in k for k in original_state_dict):
+            converted_state_dict["condition_embedder.time_proj.lora_A.weight"] = original_state_dict.pop(
+                f"time_projection.1.{lora_down_key}.weight"
+            )
+            converted_state_dict["condition_embedder.time_proj.lora_B.weight"] = original_state_dict.pop(
+                f"time_projection.1.{lora_up_key}.weight"
+            )
+            if "time_projection.1.diff_b" in original_state_dict:
+                converted_state_dict["condition_embedder.time_proj.lora_B.bias"] = original_state_dict.pop(
+                    "time_projection.1.diff_b"
+                )
+
+        if any("head.head" in k for k in state_dict):
+            converted_state_dict["proj_out.lora_A.weight"] = original_state_dict.pop(
+                f"head.head.{lora_down_key}.weight"
+            )
+            converted_state_dict["proj_out.lora_B.weight"] = original_state_dict.pop(f"head.head.{lora_up_key}.weight")
+            if "head.head.diff_b" in original_state_dict:
+                converted_state_dict["proj_out.lora_B.bias"] = original_state_dict.pop("head.head.diff_b")
+
+        for text_time in ["text_embedding", "time_embedding"]:
+            if any(text_time in k for k in original_state_dict):
+                for b_n in [0, 2]:
+                    diffusers_b_n = 1 if b_n == 0 else 2
+                    diffusers_name = (
+                        "condition_embedder.text_embedder"
+                        if text_time == "text_embedding"
+                        else "condition_embedder.time_embedder"
+                    )
+                    if any(f"{text_time}.{b_n}" in k for k in original_state_dict):
+                        converted_state_dict[f"{diffusers_name}.linear_{diffusers_b_n}.lora_A.weight"] = (
+                            original_state_dict.pop(f"{text_time}.{b_n}.{lora_down_key}.weight")
+                        )
+                        converted_state_dict[f"{diffusers_name}.linear_{diffusers_b_n}.lora_B.weight"] = (
+                            original_state_dict.pop(f"{text_time}.{b_n}.{lora_up_key}.weight")
+                        )
+                    if f"{text_time}.{b_n}.diff_b" in original_state_dict:
+                        converted_state_dict[f"{diffusers_name}.linear_{diffusers_b_n}.lora_B.bias"] = (
+                            original_state_dict.pop(f"{text_time}.{b_n}.diff_b")
+                        )
 
     if len(original_state_dict) > 0:
-        raise ValueError(f"`state_dict` should be empty at this point but has {original_state_dict.keys()=}")
+        diff = all(".diff" in k for k in original_state_dict)
+        if diff:
+            diff_keys = {k for k in original_state_dict if k.endswith(".diff")}
+            if not all("lora" not in k for k in diff_keys):
+                raise ValueError
+            logger.info(
+                "The remaining `state_dict` contains `diff` keys which we do not handle yet. If you see performance issues, please file an issue: "
+                "https://github.com/huggingface/diffusers//issues/new"
+            )
+        else:
+            raise ValueError(f"`state_dict` should be empty at this point but has {original_state_dict.keys()=}")
 
     for key in list(converted_state_dict.keys()):
         converted_state_dict[f"transformer.{key}"] = converted_state_dict.pop(key)