Add multistep DPM-Solver discrete scheduler

docs/source/api/schedulers.mdx

@@ -70,6 +70,12 @@ Original paper can be found [here](https://arxiv.org/abs/2010.02502).
 
 [[autodoc]] DDPMScheduler
 
+#### Multistep DPM-Solver
+
+Original paper can be found [here](https://arxiv.org/abs/2206.00927) and the [improved version](https://arxiv.org/abs/2211.01095). The original implementation can be found [here](https://github.com/LuChengTHU/dpm-solver).
+
+[[autodoc]] DPMSolverMultistepScheduler
+
 #### Variance exploding, stochastic sampling from Karras et. al
 
 Original paper can be found [here](https://arxiv.org/abs/2006.11239).

src/diffusers/__init__.py

@@ -42,6 +42,7 @@
     from .schedulers import (
         DDIMScheduler,
         DDPMScheduler,
+        DPMSolverMultistepScheduler,
         EulerAncestralDiscreteScheduler,
         EulerDiscreteScheduler,
         IPNDMScheduler,
@@ -92,6 +93,7 @@
     from .schedulers import (
         FlaxDDIMScheduler,
         FlaxDDPMScheduler,
+        FlaxDPMSolverMultistepScheduler,
         FlaxKarrasVeScheduler,
         FlaxLMSDiscreteScheduler,
         FlaxPNDMScheduler,

src/diffusers/pipelines/stable_diffusion/pipeline_flax_stable_diffusion.py

@@ -14,7 +14,12 @@
 
 from ...models import FlaxAutoencoderKL, FlaxUNet2DConditionModel
 from ...pipeline_flax_utils import FlaxDiffusionPipeline
-from ...schedulers import FlaxDDIMScheduler, FlaxLMSDiscreteScheduler, FlaxPNDMScheduler
+from ...schedulers import (
+    FlaxDDIMScheduler,
+    FlaxDPMSolverMultistepScheduler,
+    FlaxLMSDiscreteScheduler,
+    FlaxPNDMScheduler,
+)
 from ...utils import logging
 from . import FlaxStableDiffusionPipelineOutput
 from .safety_checker_flax import FlaxStableDiffusionSafetyChecker
@@ -43,7 +48,8 @@ class FlaxStableDiffusionPipeline(FlaxDiffusionPipeline):
         unet ([`FlaxUNet2DConditionModel`]): Conditional U-Net architecture to denoise the encoded image latents.
         scheduler ([`SchedulerMixin`]):
             A scheduler to be used in combination with `unet` to denoise the encoded image latens. Can be one of
-            [`FlaxDDIMScheduler`], [`FlaxLMSDiscreteScheduler`], or [`FlaxPNDMScheduler`].
+            [`FlaxDDIMScheduler`], [`FlaxLMSDiscreteScheduler`], [`FlaxPNDMScheduler`], or
+            [`FlaxDPMSolverMultistepScheduler`].
         safety_checker ([`FlaxStableDiffusionSafetyChecker`]):
             Classification module that estimates whether generated images could be considered offensive or harmful.
             Please, refer to the [model card](https://huggingface.co/runwayml/stable-diffusion-v1-5) for details.
@@ -57,7 +63,9 @@ def __init__(
         text_encoder: FlaxCLIPTextModel,
         tokenizer: CLIPTokenizer,
         unet: FlaxUNet2DConditionModel,
-        scheduler: Union[FlaxDDIMScheduler, FlaxPNDMScheduler, FlaxLMSDiscreteScheduler],
+        scheduler: Union[
+            FlaxDDIMScheduler, FlaxPNDMScheduler, FlaxLMSDiscreteScheduler, FlaxDPMSolverMultistepScheduler
+        ],
         safety_checker: FlaxStableDiffusionSafetyChecker,
         feature_extractor: CLIPFeatureExtractor,
         dtype: jnp.dtype = jnp.float32,

src/diffusers/pipelines/stable_diffusion/pipeline_stable_diffusion.py

@@ -11,6 +11,7 @@
 from ...pipeline_utils import DiffusionPipeline
 from ...schedulers import (
     DDIMScheduler,
+    DPMSolverMultistepScheduler,
     EulerAncestralDiscreteScheduler,
     EulerDiscreteScheduler,
     LMSDiscreteScheduler,
@@ -59,7 +60,12 @@ def __init__(
         tokenizer: CLIPTokenizer,
         unet: UNet2DConditionModel,
         scheduler: Union[
-            DDIMScheduler, PNDMScheduler, LMSDiscreteScheduler, EulerDiscreteScheduler, EulerAncestralDiscreteScheduler
+            DDIMScheduler,
+            PNDMScheduler,
+            LMSDiscreteScheduler,
+            EulerDiscreteScheduler,
+            EulerAncestralDiscreteScheduler,
+            DPMSolverMultistepScheduler,
         ],
         safety_checker: StableDiffusionSafetyChecker,
         feature_extractor: CLIPFeatureExtractor,

src/diffusers/schedulers/__init__.py

@@ -19,6 +19,7 @@
 if is_torch_available():
     from .scheduling_ddim import DDIMScheduler
     from .scheduling_ddpm import DDPMScheduler
+    from .scheduling_dpmsolver_multistep import DPMSolverMultistepScheduler
     from .scheduling_euler_ancestral_discrete import EulerAncestralDiscreteScheduler
     from .scheduling_euler_discrete import EulerDiscreteScheduler
     from .scheduling_ipndm import IPNDMScheduler
@@ -35,6 +36,7 @@
 if is_flax_available():
     from .scheduling_ddim_flax import FlaxDDIMScheduler
     from .scheduling_ddpm_flax import FlaxDDPMScheduler
+    from .scheduling_dpmsolver_multistep_flax import FlaxDPMSolverMultistepScheduler
     from .scheduling_karras_ve_flax import FlaxKarrasVeScheduler
     from .scheduling_lms_discrete_flax import FlaxLMSDiscreteScheduler
     from .scheduling_pndm_flax import FlaxPNDMScheduler