I am using IMX6SXSABRESD platform (imx-4.1.15-1.0.0_ga). I'd like to use overlay functionality of LCD Interface. I thought that fb1 is used for overlay surface and fb0 is used for background surface. I don't know how to control ALPHA_CTRL (embedded/override/multiply/rops) specified in the RM (page 2512 of IMX6SXRM.pdf Rev.1, 6/2016). Someone can explain how to use/control overlay on MX6SX?