How to obtain a drm lease from X for overlay planes as well as a primary plane?

[John Cox]

Hi all

I am on a Raspberry Pi, I want to display fullscreen video and have a
couple of overlay planes to display controls / subtitles etc. The h/w
can certainly do this.  I need to be able to do this from a starting
point where X is running.

I can successfully find X's output & crtc and grab that using
xcb_randr_create_lease and use that handle to display video. So far so
good.  But I also want to have overlay planes for subtitles etc.  The
handle I've got from the lease only seems to have a PRIMARY & a CURSOR
plane attached so I can't get anything there.

How should I be going about getting some more planes to use for
overlays? Pointers to documentation / examples gratefully received - so
far my google-foo has failed to find anything that works.

I'm sorry if this is the wrong place to ask, but if there is a better
place please say and I'll go there.

Many thanks

John Cox