[Linux-fbdev-devel] Re: fbdev, console, (video) overlay/underlay & fbtv

[Gerd K. <kr...@by...>]

> It's done. Hello Mr. Knorr :-)
> 
> The idea would be to add (video?) overlay support to the fbdev
> layer.  [ ... ]

> Would that be enough for fbtv (and similar app) ? would
> that be useful ?

fbtv does not need very much: just some piece of memory where it can ask
the bt848 to dma stuff to, and some way to enable the overlay for that.
You can have a look at the code, it already can do that on matrox cards
(by mmaping the mmio area and programming the hardware itself), see
matrox.c.

When adding such ioctls to the kernel fbdev drivers I'd try to avoid
limiting it to one overlay, which in turn means that just two ioctls are
not enougth.  IMHO it should look like this:

  (1) A ioctl to allocate a piece of offscreen memory for overlay
      (with size foo and format bar).
  (2) A ioctl to ask the driver to start overlay at x,y,w,h.
  (3) A ioctl to stop overlay
  (4) A ioctl to free the memory.

There also should be some way to figure out the supported formats.
Either a fixed list of formats and ioctl (1) returning -EINVAL for
unsupported ones or yet another ioctl to list the available ones.  It
needs to be clear what happens on console switches.  Some way to set
the chroma key color would be useful too (maybe in ioctl (2) ?).

> Could such an interface be added to ruby or should we wait
> after ruby is integrated in 2.5.x ?

BTW: What is ruby?

  Gerd

-- 
Damn lot people confuse usability and eye-candy.