HEVC Decoding for 4:2:2 sources?

NVIDIA's NVDEC supports 12 bit sources up to 8kx8k but only at 4:2:0.
Does Resolve temporarily double the vertical CbCr dimension to allow hardware accelerated support for 4:2:2 sources or does Resolve disable the hardware accelerated path for all 4:2:2 sources?

I 99.9% sure you can't decode 4:2:2 file using 4:2:0 capable decoder. It doesn't work the way you described it, specially for such a complex codecs like h265. If it would that would be actually great.

I believe Andrew is right. There is nothing to double in Cb and Cr planes before the frame comes out of decoder.