Quoting Pavlo Solntsev <pavlo.solntsev@gmail.com>:
Now, I want to submit patches to packages, e.g. libgdamm. What would be the best process: submit a patch via push request in the Debian repo, or push patches to upstream?
If it is (probably) a Debian bug, submit bug (and patch) to the Debian BTS. Ideally, using the "reportbug" command. If it is (probably) an upstream bug, submit the bug to upstream in the form prefered by upstream. Cheers