Perhaps you want this :

sub subroutine_1 {
  my $val = subroutine_2();
  print "$val this is subroutine_2 output!";
}

sub subroutine_2 {
  return "w00t!";
}
[download]

It does not pass it back to subroutine_2 but should give you a rough idea of how things like these work.