Re: Best way to support mulitple planes?

[Ondrej Zajicek <santiago@crfreenet.org>]

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On Sun, Sep 16, 2007 at 10:38:30AM +0800, Antonino A. Daplas wrote:
> On Thu, 2007-09-13 at 16:29 -0500, Timur Tabi wrote:
> > Ville Syrjälä wrote:
> > 
> > Would it be correct to say that applications expect the separate devices 
> > (/dev/fb0, /dev/fb1, etc) to represent different monitors?
> 
> That's not necessarily true. In the strictest sense, each /dev/fbx
> device represents one memory region.  Whether that memory region is
> attached to zero, one or more monitors is up to the driver.

I always perceived fb device as a representation of a sequencer/scanner -
probably because almost all ioctls on a fbdev device make sense for
sequencer (and associated CRT controller and DAC).

> We do not have the infrastructure yet to separate output devices from
> the framebuffer so multi-head/mergefb implementations will still be
> driver specific.

I think it can be done with (almost) present infrastructure - 
one fb device per sequencer (sharing all memory of a card). We can
do  most of multi-head/mergedfb configurations using appropriate vxyres/pan
setting. Perhaps one new ioctl to assign output ports to sequencers and
one new sysfs option for optional memory split (separate parts of memory
accessible through each fb device instead of all memory accessible through
both fb devices).

-- 
Elen sila lumenn' omentielvo

Ondrej 'SanTiago' Zajicek (email: santiago@crfreenet.org, jabber: santiago@njs.netlab.cz)
OpenPGP encrypted e-mails preferred (KeyID 0x11DEADC3, wwwkeys.pgp.net)
"To err is human -- to blame it on a computer is even more so."

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