fix: propagate parallel_config through create_default_diffusion (#1878)

Signed-off-by: lishunyang <lishunyang12@163.com>
Signed-off-by: Hongsheng Liu <liuhongsheng4@huawei.com>
Co-authored-by: Gao Han <hgaoaf@connect.ust.hk>
Co-authored-by: Hongsheng Liu <liuhongsheng4@huawei.com>

vllm_omni/diffusion/data.py

@@ -514,12 +514,11 @@ class OmniDiffusionConfig:
         initial_master_port = (self.master_port or 30005) + random.randint(0, 100)
         self.master_port = self.settle_port(initial_master_port, 37)
 
-        # Convert parallel_config dict to DiffusionParallelConfig if needed
-        # This must be done before accessing parallel_config.world_size
-        if isinstance(self.parallel_config, dict):
-            self.parallel_config = DiffusionParallelConfig.from_dict(self.parallel_config)
+        # Convert parallel_config dict/DictConfig to DiffusionParallelConfig
+        # Use Mapping to handle both plain dicts and OmegaConf DictConfig
+        if isinstance(self.parallel_config, Mapping):
+            self.parallel_config = DiffusionParallelConfig.from_dict(dict(self.parallel_config))
         elif not isinstance(self.parallel_config, DiffusionParallelConfig):
-            # If it's neither dict nor DiffusionParallelConfig, use default config
             self.parallel_config = DiffusionParallelConfig()
 
         if self.num_gpus is None: