[Fix] Fix lint and mmcv version requirement for IPU.

configs/vision_transformer/vit-base-p16_ft-4xb544-ipu_in1k.py

@@ -10,6 +10,8 @@ paramwise_cfg = dict(custom_keys={
     '.pos_embed': dict(decay_mult=0.0)
 })
 
+pretrained = 'https://download.openmmlab.com/mmclassification/v0/vit/pretrain/vit-base-p16_3rdparty_pt-64xb64_in1k-224_20210928-02284250.pth'  # noqa
+
 model = dict(
     head=dict(
         loss=dict(type='CrossEntropyLoss', loss_weight=1.0, _delete_=True), ),
@@ -17,7 +19,7 @@ model = dict(
         img_size=224,
         init_cfg=dict(
             type='Pretrained',
-            checkpoint='https://download.openmmlab.com/mmclassification/v0/vit/pretrain/vit-base-p16_3rdparty_pt-64xb64_in1k-224_20210928-02284250.pth',  # noqa
+            checkpoint=pretrained,
             _delete_=True,
             prefix='backbone')))
 

mmcls/datasets/builder.py

@@ -8,10 +8,14 @@ import numpy as np
 import torch
 from mmcv.parallel import collate
 from mmcv.runner import get_dist_info
-from mmcv.utils import (IS_IPU_AVAILABLE, Registry, build_from_cfg,
-                        digit_version)
+from mmcv.utils import Registry, build_from_cfg, digit_version
 from torch.utils.data import DataLoader
 
+try:
+    from mmcv.utils import IS_IPU_AVAILABLE
+except ImportError:
+    IS_IPU_AVAILABLE = False
+
 if platform.system() != 'Windows':
     # https://github.com/pytorch/pytorch/issues/973
     import resource