The AGC class was not documented while developing. Extend that to reference the origins of the implementation, and improve the descriptions on how the algorithm operates internally. While at it, rename the functions which have bad names. Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com> Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>