Documentation/video4linux/gspca.txt

The fact that the kernel is licensed under the GPL does mean that a complying party has to
publish it's code changes.

This does not mean they have to submit them to upstream even though this is often done out of
courtesy.
Furthermore, _nothing_ in the GPL stipulates that Debian or Ubuntu or anyone else takes some
patches from Xandros and adds them to their distribution.
Furthermore, I'd argue that Distributions like Debian and Fedora, who track upstream quite
closely, will not be applying third-party patches from Xandros.

The way of getting changes into these distributions is to submit code to upstream and work on
it until it has been merged into mainline, then the changes will trickle down to the
distributions again.