Carvajal quit Real in August for Bayer - but could be playing first team football for Madrid given their spate of defensive injuries.
Carvajal, however, has no regrets: "Right now, I could be in the Castilla and with options of moving up to the first team, but it is still the second division.
"Now I'm playing in the Bundesliga.
"Barcelona are committed to a youth policy that is going well. Choices are left to the coach, who gives them that opportunity and that faith is being met."