Keep Coding

I have an Activity where the 1st Fragment (whose orientation is locked) solicits input from a user. This data is used to determine how to orient the 2nd Fragment. This orientation will also be locked.
I am guessing I will have to make a call to setRequestedOrientation( ActivityInfo.SCREEN_ORIENTATION_PORTRAIT) either from the Activity or the 2nd Fragment.
My question is where best to do this. Does it really make a difference? Can this action be performed w/o undergoing an Activity restart?

If changing the setRequestedOrientation state requires the screen to rotate then it will restart the activity.
For example if you request ActivityInfo.SCREEN_ORIENTATION_PORTRAIT while the screen is in landscape, it will restart.
However it will not restart if the phone is already in that orientation.