NemotronH default mamba_ssm_cache_dtype=float32; enable auto-hook for NemotronHNanoVLV2Config (#39032)

Signed-off-by: Netanel Haber <58652339+netanel-haber@users.noreply.github.com>

vllm/model_executor/models/config.py

@@ -7,7 +7,9 @@ from vllm.logger import init_logger
 from vllm.utils.math_utils import round_up
 
 if TYPE_CHECKING:
-    from vllm.config import ModelConfig, VllmConfig
+    from transformers import PretrainedConfig
+
+    from vllm.config import CacheConfig, ModelConfig, VllmConfig
 
 
 logger = init_logger(__name__)
@@ -346,17 +348,20 @@ class MambaModelConfig(VerifyAndUpdateConfig):
 
 
 class NemotronHForCausalLMConfig(VerifyAndUpdateConfig):
-    @staticmethod
-    def verify_and_update_config(vllm_config: "VllmConfig") -> None:
+    DEFAULT_MAMBA_SSM_CACHE_DTYPE = "float32"
+    """Only `float32` is known to have no accuracy issues by default."""
+
+    @classmethod
+    def update_mamba_ssm_cache_dtype(
+        cls, *, cache_config: "CacheConfig", hf_config: "PretrainedConfig"
+    ) -> None:
         """Update mamba_ssm_cache_dtype for NemotronH models when set to 'auto'
         (or not explicitly set), to the value specified in the HF config, or to
-        float16 if not specified.
+        `float32` if not specified.
         """
-        cache_config = vllm_config.cache_config
         if cache_config.mamba_ssm_cache_dtype == "auto":
-            hf_config = vllm_config.model_config.hf_config
             mamba_ssm_cache_dtype = getattr(
-                hf_config, "mamba_ssm_cache_dtype", "float16"
+                hf_config, "mamba_ssm_cache_dtype", cls.DEFAULT_MAMBA_SSM_CACHE_DTYPE
             )
             logger.info(
                 "Updating mamba_ssm_cache_dtype to '%s' for NemotronH model",
@@ -364,8 +369,22 @@ class NemotronHForCausalLMConfig(VerifyAndUpdateConfig):
             )
             cache_config.mamba_ssm_cache_dtype = mamba_ssm_cache_dtype
 
+    @classmethod
+    def verify_and_update_config(cls, vllm_config: "VllmConfig") -> None:
+        cls.update_mamba_ssm_cache_dtype(
+            cache_config=vllm_config.cache_config,
+            hf_config=vllm_config.model_config.hf_config,
+        )
+
 
 class NemotronHNanoVLV2Config(VerifyAndUpdateConfig):
+    @classmethod
+    def verify_and_update_config(cls, vllm_config: "VllmConfig") -> None:
+        NemotronHForCausalLMConfig.update_mamba_ssm_cache_dtype(
+            cache_config=vllm_config.cache_config,
+            hf_config=vllm_config.model_config.hf_config.text_config,
+        )
+
     @staticmethod
     def verify_and_update_model_config(model_config: "ModelConfig") -> None:
         mm_config = model_config.multimodal_config