[V1][Bugfix] Fix handing of `second_per_grid_ts` for Qwen2-VL & Qwen2.5-VL (#14548)

Signed-off-by: Roger Wang <ywang@roblox.com>

vllm/model_executor/layers/rotary_embedding.py

@@ -923,14 +923,19 @@ class MRotaryEmbedding(RotaryEmbedding):
     def get_input_positions(
         input_tokens: List[int],
         hf_config: PretrainedConfig,
-        image_grid_thw: Union[List[List[int]], torch.Tensor],
-        video_grid_thw: Union[List[List[int]], torch.Tensor],
-        second_per_grid_ts: Optional[List[float]] = None,
+        image_grid_thw: Optional[Union[List[List[int]], torch.Tensor]],
+        video_grid_thw: Optional[Union[List[List[int]], torch.Tensor]],
+        second_per_grid_ts: Optional[List[float]],
         context_len: int = 0,
         seq_len: Optional[int] = None,
     ) -> Tuple[List[List[int]], int]:
         """Get mrope input positions and delta value."""
 
+        image_grid_thw = [] if image_grid_thw is None else image_grid_thw
+        video_grid_thw = [] if video_grid_thw is None else video_grid_thw
+        second_per_grid_ts = [] if second_per_grid_ts is None else \
+            second_per_grid_ts
+
         llm_positions, mrope_position_delta = \
             MRotaryEmbedding.get_input_positions_tensor(
                 input_tokens=input_tokens,
@@ -950,7 +955,7 @@ class MRotaryEmbedding(RotaryEmbedding):
         hf_config: PretrainedConfig,
         image_grid_thw: Union[List[List[int]], torch.Tensor],
         video_grid_thw: Union[List[List[int]], torch.Tensor],
-        second_per_grid_ts: Optional[List[float]] = None,
+        second_per_grid_ts: List[float],
         context_len: int = 0,
         seq_len: Optional[int] = None,
     ) -> Tuple[torch.Tensor, int]:
@@ -1006,7 +1011,7 @@ class MRotaryEmbedding(RotaryEmbedding):
                     video_grid_thw[video_index][2],
                 )
                 video_second_per_grid_t = 1.0
-                if second_per_grid_ts is not None:
+                if second_per_grid_ts:
                     video_second_per_grid_t = second_per_grid_ts[video_index]
                 video_index += 1
                 remain_videos -= 1