pixel transparency - TI81XXFB_BLENDING_PIXEL not supported ?

Hello,

I am using graphic sdk, with eglfs. (I use DM8148.)

On trying to configure:

1. transparent keying disable

2, TI81XXFB_BLENDING_PIXEL 

I get that only the video layer is displayed while the graphic is not displayed at all , I probably missed some required configurations ?

/*Set Global Alpha Blending*/
regp.blendtype = TI81XXFB_BLENDING_PIXEL;


if (ioctl(display_fd, TIFB_SET_PARAMS, &regp) < 0) {
perror ("TIFB_SET_PARAMS.\n");
close(display_fd);
exit(1);
}

Is it poosible to get effect of opacity (alpha blending) between the video and the graphics ?

Does controling /fbX affects only graphic layers ? What about the video layer ?

Do I also need to change the video for alpha blending or is it suffecient to configure the graphic layer for alpha blending ?

Thanks for any idea,

Ran