PixArt auto checkpoint loader

Needs better logic for diffusers weights

PixArt/loader.py

@@ -5,6 +5,7 @@ import comfy.model_base
 import comfy.utils
 import comfy.conds
 import torch
+import math 
 from comfy import model_management
 from .diffusers_convert import convert_state_dict
 
@@ -45,7 +46,7 @@ class EXM_PixArt_Model(comfy.model_base.BaseModel):
 
 		return out
 
-def load_pixart(model_path, model_conf):
+def load_pixart(model_path, model_conf=None):
 	state_dict = comfy.utils.load_torch_file(model_path)
 	state_dict = state_dict.get("model", state_dict)
 
@@ -58,6 +59,10 @@ def load_pixart(model_path, model_conf):
 	if "adaln_single.linear.weight" in state_dict:
 		state_dict = convert_state_dict(state_dict) # Diffusers
 
+	# guess auto config
+	if model_conf is None:
+		model_conf = guess_pixart_config(state_dict)
+
 	parameters = comfy.utils.calculate_parameters(state_dict)
 	unet_dtype = model_management.unet_dtype(model_params=parameters)
 	load_device = comfy.model_management.get_torch_device()
@@ -113,3 +118,64 @@ def load_pixart(model_path, model_conf):
 		current_device = "cpu",
 	)
 	return model_patcher
+
+def guess_pixart_config(sd):
+	"""
+	Guess config based on converted state dict.
+	"""
+	# Shared settings based on DiT_XL_2 - could be enumerated
+	config = {
+		"num_heads"   :   16, # get from attention
+		"patch_size"  :    2, # final layer I guess?
+		"hidden_size" : 1152, # pos_embed.shape[2]
+	}
+	config["depth"] = sum([key.endswith(".attn.proj.weight") for key in sd.keys()]) or 28
+
+	try:
+		# this is not present in the diffusers version for sigma?
+		config["model_max_length"] = sd["y_embedder.y_embedding"].shape[0]
+	except KeyError:
+		# need better logic to guess this
+		config["model_max_length"] = 300
+
+	if "pos_embed" in sd:
+		config["input_size"] = int(math.sqrt(sd["pos_embed"].shape[1])) * config["patch_size"]
+		config["pe_interpolation"] = config["input_size"] // (512//8) # dumb guess
+
+	target_arch = "PixArtMS"
+	if config["model_max_length"] == 300:
+		# Sigma
+		target_arch = "PixArtMSSigma"
+		config["micro_condition"] = False
+		if "input_size" not in config:
+			# The diffusers weights for 1K/2K are exactly the same...?
+			# replace patch embed logic with HyDiT?
+			print(f"PixArt: diffusers weights - 2K model will be broken, use manual loading!")
+			config["input_size"] = 1024//8
+	else:
+		# Alpha
+		if "csize_embedder.mlp.0.weight" in sd:
+			# MS (microconds)
+			target_arch = "PixArtMS"
+			config["micro_condition"] = True
+			if "input_size" not in config:
+				config["input_size"] = 1024//8
+				config["pe_interpolation"] = 2
+		else:
+			# PixArt
+			target_arch = "PixArt"
+			if "input_size" not in config:
+				config["input_size"] = 512//8
+				config["pe_interpolation"] = 1
+
+	print("PixArt guessed config:", target_arch, config)
+	return {
+		"target": target_arch,
+		"unet_config": config,
+		"sampling_settings": {
+			"beta_schedule" : "sqrt_linear",
+			"linear_start"  : 0.0001,
+			"linear_end"    : 0.02,
+			"timesteps"     : 1000,
+		}	
+	}

PixArt/nodes.py

@@ -32,6 +32,21 @@ class PixArtCheckpointLoader:
 		)
 		return (model,)
 
+class PixArtCheckpointLoaderSimple(PixArtCheckpointLoader):
+	@classmethod
+	def INPUT_TYPES(s):
+		return {
+			"required": {
+				"ckpt_name": (folder_paths.get_filename_list("checkpoints"),),
+			}
+		}
+	TITLE = "PixArt Checkpoint Loader (auto)"
+
+	def load_checkpoint(self, ckpt_name):
+		ckpt_path = folder_paths.get_full_path("checkpoints", ckpt_name)
+		model = load_pixart(model_path=ckpt_path)
+		return (model,)
+
 class PixArtResolutionSelect():
 	@classmethod
 	def INPUT_TYPES(s):
@@ -245,6 +260,7 @@ class PixArtT5FromSD3CLIP:
 
 NODE_CLASS_MAPPINGS = {
 	"PixArtCheckpointLoader" : PixArtCheckpointLoader,
+	"PixArtCheckpointLoaderSimple" : PixArtCheckpointLoaderSimple,
 	"PixArtResolutionSelect" : PixArtResolutionSelect,
 	"PixArtLoraLoader" : PixArtLoraLoader,
 	"PixArtT5TextEncode" : PixArtT5TextEncode,