do we need a special permit to visit Nyinchi and the surroundings?

Hello, we plan to visit Nyinchi and stay there 3 days sometime in May, and plan to visit the entrance of Tsangpo gorge and enjoy the scenic mountain of Namcha Barwa, also we plan to go up to 徒步嘎龙拉,thank you for your advice.
Best Regards,
Francois