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

[Romain D. <do...@ir...>]

Gerd Knorr wrote:
> That's IMHO no excuse.  The old ones can't be changed without breaking
> compatibility of course, but for new ones it should be done the
> RightWay[tm].

You're right, but then you need to know what prefix you can
use. I asked for pm3fb and got no response. I don't know
what to use for adding IOCTL to generic FB stuff...

And as long as it's a draft it's easy to change :-)

> And please add some comments saying which is planar/packed.

will do.

> There still would be image data in the buffer, and the image has some
> width / height.  Even if you are going to use that image buffer for
> something else than overlay (texture, bitblit or whatever).
> 
> IMHO it is important to let the driver pick the buffer size to avoid
> trouble due to hardware limitations / alignment issues / ...
> which the application doesn't know about.

My current idea was the app was told about alignement issue
in _CAP, and could require the size it needs by computing
(pixelsize*paddedX*paddedY), and require that size or more.
The driver return the base adress of the buffer (or 0 for
failure) and the actual size of the buffer (>= required
or 0 for failure). Also, it returns the number of the buffer
if it was (-1) as you suggested.

I agree the driver can do the size computing by itself,
but I still thinks it's better to keep the actual
data size in the _START call to allow for larger-than-
image buffer.

> Hmm, is this _really_ a problem?  Do you want to mix that with
> console?  I'd expect graphic applications whould use that only,
> like fbtv, dvd players (there is a fb-based one IIRC), ...

Yes, if you want to be able to use the text console while
displaying stuff like video or a still image. One could
use `fbi' (:-) to display a background picture or `fbtv'
for background movie/video stream. It's an overlay,
it should behave nicely toward the foreground app,
even fbcon. IMHO :-)

-- 
DOLBEAU Romain               | l'histoire est entierement vraie, puisque
ENS Cachan / Ker Lann        |     je l'ai imaginee d'un bout a l'autre
do...@ir...             |           -- Boris Vian