72 (respectively 144 hours) visa free in Shanghai

I am reading that I have to inform airline carrier about intention to apply for 72/144 free transit in Shanghai before boarding flight. I have contacted China Eastern Airline and their representative told me that it's sufficient to enter passport information in my flight ticket booking, nothing else has to be done. Several online websites states airline has to inform immigration authority in Shanghai about my intention to enter China under this policy in advance but representative of China Eastern Airline informed me bit differently. Could you please let me know what is the proper policy? Is entering passport details in my flight ticket booking sufficient if my transit port of entry will be Shanghai Pudong Airport? Thank you.