Fix PixtralHF missing spatial_merge_size (#17571)

Signed-off-by: mgoin <mgoin64@gmail.com>

vllm/model_executor/models/llava.py

@@ -354,9 +354,8 @@ class PixtralHFMultiModalProcessor(
         image_token_id = hf_config.image_token_index
         image_end_id = vocab[processor.image_end_token]
 
-        vision_config = hf_config.vision_config
-        assert isinstance(vision_config, PixtralVisionConfig)
-        encoder_info = PixtralHFEncoderInfo(vision_config)
+        assert isinstance(hf_config.vision_config, PixtralVisionConfig)
+        encoder_info = PixtralHFEncoderInfo(hf_config)
 
         def get_replacement(item_idx: int):
             images = mm_items.get_items("image", ImageProcessorItems)

vllm/model_executor/models/mistral3.py

@@ -272,12 +272,8 @@ class Mistral3MultiModalProcessor(
         image_token_id = hf_config.image_token_index
         image_end_id = vocab[processor.image_end_token]
 
-        vision_config = hf_config.vision_config
-        assert isinstance(vision_config, PixtralVisionConfig)
-        # Need to sneak in spatial_merge_size for Mistral3
-        vision_config.spatial_merge_size = getattr(hf_config,
-                                                   "spatial_merge_size", 1)
-        encoder_info = PixtralHFEncoderInfo(vision_config)
+        assert isinstance(hf_config.vision_config, PixtralVisionConfig)
+        encoder_info = PixtralHFEncoderInfo(hf_config)
 
         def get_replacement(item_idx: int):
             images = mm_items.get_items("image", ImageProcessorItems)

vllm/model_executor/models/pixtral.py

@@ -916,8 +916,9 @@ class PixtralHFEncoderInfo(VisionEncoderInfo[PixtralVisionConfig]):
         return self.vision_config.image_size
 
     def get_patch_size(self) -> int:
-        return (self.vision_config.patch_size *
-                self.vision_config.spatial_merge_size)
+        # spatial_merge_size is needed for Mistral3
+        spatial_merge_size = getattr(self.hf_config, "spatial_merge_size", 1)
+        return self.vision_config.patch_size * spatial_merge_size
 
     def get_patch_grid_length(self) -> int:
         image_size, patch_size = self.get_image_size(), self.get_patch_size()

vllm/model_executor/models/vision.py

@@ -19,10 +19,11 @@ _C = TypeVar("_C", bound=PretrainedConfig)
 
 class VisionEncoderInfo(ABC, Generic[_C]):
 
-    def __init__(self, vision_config: _C) -> None:
+    def __init__(self, hf_config: _C) -> None:
         super().__init__()
 
-        self.vision_config = vision_config
+        self.hf_config = hf_config
+        self.vision_config = hf_config.vision_config
 
     @abstractmethod
     def get_num_image_tokens(
@@ -57,18 +58,14 @@ def get_vision_encoder_info(
     from .pixtral import PixtralHFEncoderInfo, PixtralVisionConfig
     from .siglip import SiglipEncoderInfo, SiglipVisionConfig
 
-    vision_config = hf_config.vision_config
-    if isinstance(vision_config, CLIPVisionConfig):
-        return CLIPEncoderInfo(vision_config)
-    if isinstance(vision_config, PixtralVisionConfig):
-        # Need to sneak in spatial_merge_size for Mistral3
-        vision_config.spatial_merge_size = getattr(hf_config,
-                                                   "spatial_merge_size", 1)
-        return PixtralHFEncoderInfo(vision_config)
-    if isinstance(vision_config, SiglipVisionConfig):
-        return SiglipEncoderInfo(vision_config)
-
-    msg = f"Unsupported vision config: {type(vision_config)}"
+    if isinstance(hf_config.vision_config, CLIPVisionConfig):
+        return CLIPEncoderInfo(hf_config)
+    if isinstance(hf_config.vision_config, PixtralVisionConfig):
+        return PixtralHFEncoderInfo(hf_config)
+    if isinstance(hf_config.vision_config, SiglipVisionConfig):
+        return SiglipEncoderInfo(hf_config)
+
+    msg = f"Unsupported vision config: {type(hf_config.vision_config)}"
     raise NotImplementedError(msg)