Validate --task speed CPU fix (#10244)

segment/val.py

@@ -444,7 +444,7 @@ def main(opt):
 
     else:
         weights = opt.weights if isinstance(opt.weights, list) else [opt.weights]
-        opt.half = True  # FP16 for fastest results
+        opt.half = torch.cuda.is_available() and opt.device != 'cpu'  # FP16 for fastest results
         if opt.task == 'speed':  # speed benchmarks
             # python val.py --task speed --data coco.yaml --batch 1 --weights yolov5n.pt yolov5s.pt...
             opt.conf_thres, opt.iou_thres, opt.save_json = 0.25, 0.45, False