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52 lines
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Python

# SPDX-License-Identifier: Apache-2.0
import torch
import torch.nn as nn
from fastvideo.layers.activation import get_act_fn
from fastvideo.layers.linear import ReplicatedLinear
from fastvideo.layers.quantization import QuantizationConfig
class MLP(nn.Module):
"""
MLP for DiT blocks, NO gated linear units
"""
def __init__(
self,
input_dim: int,
mlp_hidden_dim: int,
output_dim: int | None = None,
bias: bool = True,
act_type: str = "gelu_pytorch_tanh",
dtype: torch.dtype | None = None,
prefix: str = "",
quant_config: QuantizationConfig | None = None,
):
super().__init__()
self.fc_in = ReplicatedLinear(
input_dim,
mlp_hidden_dim, # For activation func like SiLU that need 2x width
bias=bias,
params_dtype=dtype,
quant_config=quant_config,
prefix=f"{prefix}.fc_in",
)
self.act = get_act_fn(act_type)
if output_dim is None:
output_dim = input_dim
self.fc_out = ReplicatedLinear(mlp_hidden_dim,
output_dim,
bias=bias,
params_dtype=dtype,
quant_config=quant_config,
prefix=f"{prefix}.fc_out")
def forward(self, x: torch.Tensor) -> torch.Tensor:
x, _ = self.fc_in(x)
x = self.act(x)
x, _ = self.fc_out(x)
return x