Some top layer parames of reference_unet don't need grad, what is the reason?

[BugsMaker0513]

Some top layer parames of reference_unet don't need grad

for name, param in reference_unet.named_parameters():
    if "up_blocks.3" in name:
        param.requires_grad_(False)
    else:
        param.requires_grad_(True)

[hjrPhoebus]

same question

[iyc2]

same question +1

[penguin4466]

same question +2