backward compatibility

src/f5_tts/model/modules.py

@@ -443,7 +443,7 @@ class AttnProcessor:
     def __init__(
         self,
         pe_attn_head: int | None = None,  # number of attention head to apply rope, None for all
-        attn_backend: str = "flash_attn",
+        attn_backend: str = "torch",  # "torch" or "flash_attn"
         attn_mask_enabled: bool = True,
     ):
         if attn_backend == "flash_attn":
@@ -655,7 +655,7 @@ class DiTBlock(nn.Module):
         dropout=0.1,
         qk_norm=None,
         pe_attn_head=None,
-        attn_backend="flash_attn",
+        attn_backend="torch",  # "torch" or "flash_attn"
         attn_mask_enabled=True,
     ):
         super().__init__()