Upvote:3
There is some inconsitency that is published by the German diplomatic missions as far as visas are concerned so here goes:
Save these you will need a transit visa on your way back. Also all of this is conditional on you transiting through one of 6 airports in Germany (Cologne/Bonn, Munich, Dusseldorf, Frankfurt, Berlin, or Hamburg) and don't have another stop in between in a different Schengen country.
Having said all that it might be a good idea to contact a German consulate to get the information directly since the published information on their consulate pages is somewhat inconsistent.