Fixes for issue #33763 in idefics2 model (#33766)

src/transformers/models/idefics2/modeling_idefics2.py

@@ -1348,17 +1348,18 @@ def forward(
         past_seen_tokens = 0
         # kept for BC (non `Cache` `past_key_values` inputs)
         return_legacy_cache = False
-        if use_cache and not isinstance(past_key_values, Cache):
-            return_legacy_cache = True
-            if past_key_values is None:
-                past_key_values = DynamicCache()
-            else:
-                past_key_values = DynamicCache.from_legacy_cache(past_key_values)
-                logger.warning_once(
-                    "We detected that you are passing `past_key_values` as a tuple of tuples. This is deprecated and "
-                    "will be removed in v4.47. Please convert your cache or use an appropriate `Cache` class "
-                    "(https://huggingface.co/docs/transformers/kv_cache#legacy-cache-format)"
-                )
+        if use_cache:
+            if not isinstance(past_key_values, Cache):
+                return_legacy_cache = True
+                if past_key_values is None:
+                    past_key_values = DynamicCache()
+                else:
+                    past_key_values = DynamicCache.from_legacy_cache(past_key_values)
+                    logger.warning_once(
+                        "We detected that you are passing `past_key_values` as a tuple of tuples. This is deprecated and "
+                        "will be removed in v4.47. Please convert your cache or use an appropriate `Cache` class "
+                        "(https://huggingface.co/docs/transformers/kv_cache#legacy-cache-format)"
+                    )
             past_seen_tokens = past_key_values.get_seq_length()
 
         if inputs_embeds is not None and input_ids is None and past_seen_tokens == 0: