remove str option for quantization config in torchao

Author: howardzhang-cv

docs/source/en/quantization/torchao.md

@@ -29,24 +29,7 @@ from diffusers import DiffusionPipeline, PipelineQuantizationConfig, TorchAoConf
 from torchao.quantization import Int8WeightOnlyConfig
 
 pipeline_quant_config = PipelineQuantizationConfig(
-    quant_mapping={"transformer": TorchAoConfig(Int8WeightOnlyConfig(group_size=128)))}
-)
-pipeline = DiffusionPipeline.from_pretrained(
-    "black-forest-labs/FLUX.1-dev",
-    quantization_config=pipeline_quant_config,
-    torch_dtype=torch.bfloat16,
-    device_map="cuda"
-)
-```
-
-For simple use cases, you could also provide a string identifier in [`TorchAo`] as shown below.
-
-```py
-import torch
-from diffusers import DiffusionPipeline, PipelineQuantizationConfig, TorchAoConfig
-
-pipeline_quant_config = PipelineQuantizationConfig(
-    quant_mapping={"transformer": TorchAoConfig("int8wo")}
+    quant_mapping={"transformer": TorchAoConfig(Int8WeightOnlyConfig(group_size=128))}
 )
 pipeline = DiffusionPipeline.from_pretrained(
     "black-forest-labs/FLUX.1-dev",
@@ -91,17 +74,6 @@ Weight-only quantization stores the model weights in a specific low-bit data typ
 
 Dynamic activation quantization stores the model weights in a low-bit dtype, while also quantizing the activations on-the-fly to save additional memory. This lowers the memory requirements from model weights, while also lowering the memory overhead from activation computations. However, this may come at a quality tradeoff at times, so it is recommended to test different models thoroughly.
 
-The quantization methods supported are as follows:
-
-| **Category** | **Full Function Names** | **Shorthands** |
-|--------------|-------------------------|----------------|
-| **Integer quantization** | `int4_weight_only`, `int8_dynamic_activation_int4_weight`, `int8_weight_only`, `int8_dynamic_activation_int8_weight` | `int4wo`, `int4dq`, `int8wo`, `int8dq` |
-| **Floating point 8-bit quantization** | `float8_weight_only`, `float8_dynamic_activation_float8_weight`, `float8_static_activation_float8_weight` | `float8wo`, `float8wo_e5m2`, `float8wo_e4m3`, `float8dq`, `float8dq_e4m3`, `float8dq_e4m3_tensor`, `float8dq_e4m3_row` |
-| **Floating point X-bit quantization** | `fpx_weight_only` | `fpX_eAwB` where `X` is the number of bits (1-7), `A` is exponent bits, and `B` is mantissa bits. Constraint: `X == A + B + 1` |
-| **Unsigned Integer quantization** | `uintx_weight_only` | `uint1wo`, `uint2wo`, `uint3wo`, `uint4wo`, `uint5wo`, `uint6wo`, `uint7wo` |
-
-Some quantization methods are aliases (for example, `int8wo` is the commonly used shorthand for `int8_weight_only`). This allows using the quantization methods described in the torchao docs as-is, while also making it convenient to remember their shorthand notations.
-
 Refer to the [official torchao documentation](https://docs.pytorch.org/ao/stable/index.html) for a better understanding of the available quantization methods and the exhaustive list of configuration options available.
 
 ## Serializing and Deserializing quantized models
@@ -111,8 +83,9 @@ To serialize a quantized model in a given dtype, first load the model with the d
 ```python
 import torch
 from diffusers import AutoModel, TorchAoConfig
+from torchao.quantization import Int8WeightOnlyConfig
 
-quantization_config = TorchAoConfig("int8wo")
+quantization_config = TorchAoConfig(Int8WeightOnlyConfig())
 transformer = AutoModel.from_pretrained(
     "black-forest-labs/Flux.1-Dev",
     subfolder="transformer",
@@ -137,18 +110,19 @@ image = pipe(prompt, num_inference_steps=30, guidance_scale=7.0).images[0]
 image.save("output.png")
 ```
 
-If you are using `torch<=2.6.0`, some quantization methods, such as `uint4wo`, cannot be loaded directly and may result in an `UnpicklingError` when trying to load the models, but work as expected when saving them. In order to work around this, one can load the state dict manually into the model. Note, however, that this requires using `weights_only=False` in `torch.load`, so it should be run only if the weights were obtained from a trustable source.
+If you are using `torch<=2.6.0`, some quantization methods, such as `uint4` weight-only, cannot be loaded directly and may result in an `UnpicklingError` when trying to load the models, but work as expected when saving them. In order to work around this, one can load the state dict manually into the model. Note, however, that this requires using `weights_only=False` in `torch.load`, so it should be run only if the weights were obtained from a trustable source.
 
 ```python
 import torch
 from accelerate import init_empty_weights
 from diffusers import FluxPipeline, AutoModel, TorchAoConfig
+from torchao.quantization import IntxWeightOnlyConfig
 
 # Serialize the model
 transformer = AutoModel.from_pretrained(
     "black-forest-labs/Flux.1-Dev",
     subfolder="transformer",
-    quantization_config=TorchAoConfig("uint4wo"),
+    quantization_config=TorchAoConfig(IntxWeightOnlyConfig(dtype=torch.uint4)),
     torch_dtype=torch.bfloat16,
 )
 transformer.save_pretrained("/path/to/flux_uint4wo", safe_serialization=False, max_shard_size="50GB")