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fix(minimax): enable autocast on all accelerators in VAE decoding - #14766

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li-lizhe wants to merge 2 commits into
huggingface:mainfrom
li-lizhe:fix/minimax-autocast-device
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li-lizhe wants to merge 2 commits into
huggingface:mainfrom
li-lizhe:fix/minimax-autocast-device

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Description: The VAE decode block in the MiniMax H3 modular pipeline only enables fp16 autocast on CUDA devices (enabled=device.type == "cuda"), which disables autocast on other accelerators such as Ascend NPU, Intel XPU, or Apple MPS.

Without autocast on NPU, the VAE decode runs in fp32 (or the tensor's dtype without fp16 acceleration), causing suboptimal performance and potential dtype mismatches when the pipeline expects half-precision computation.

Change:

  • enabled=device.type == "cuda"enabled=device.type != "cpu"
  • Autocast fp16 is now enabled on all accelerator devices while remaining disabled on CPU

Verification on Ascend 910B NPU (torch 2.14.0a0 + torch_npu):

  • torch.autocast(device_type="npu", dtype=torch.float16, enabled=True) produces fp16 output (out.dtype=torch.float16)
  • torch.autocast(device_type="npu", dtype=torch.float16, enabled=False) produces fp32 output (out.dtype=torch.float32)
  • Both work correctly on NPU

The `get_i2v_mask` method had a hardcoded `device="cuda"` default,
which crashes on non-CUDA accelerators (Ascend NPU, etc.) with
"Torch not compiled with CUDA enabled" when called without an
explicit device argument.

Change the default to None and resolve via `self._execution_device`,
matching the pattern used across other pipeline methods.

Verified on Ascend 910B NPU: torch.zeros(device="cuda") crashes,
fix with device-agnostic resolution creates tensors on the correct
device.
The VAE decode block in the MiniMax H3 pipeline only enables fp16
autocast on CUDA (`enabled=device.type == "cuda"`), which disables
autocast on other accelerators such as Ascend NPU, causing
suboptimal performance and potential dtype mismatches.

Change to `enabled=device.type != "cpu"` so autocast is enabled on
any accelerator device while remaining disabled on CPU.

Verified on Ascend 910B NPU: torch.autocast(device_type="npu",
dtype=torch.float16, enabled=True) correctly computes in fp16.
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Hi @li-lizhe, thanks for the PR! It does not appear to link an issue it fixes. If this PR addresses an existing issue, please add a closing keyword (e.g. Fixes #1234) to the PR description so the issue is linked. See the contribution guide for more details. If this PR intentionally does not fix a tracked issue, a maintainer can add the no-issue-needed label to silence this reminder.

Please note that PRs without a linked issue are likely to be automatically closed 10 days after this notice.

Once the PR links an issue (or gets the no-issue-needed label), you can ignore this message — it stays here as a comment, but it no longer applies.

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