On 7/28/06, Dieter <[EMAIL PROTECTED]> wrote:
> > > I think that it is the other way around. PC MotherBoards are going to
> > > request a VGA mode that needs to be supported. This VGA mode is only
> > > used until the OS loads a graphics driver. Linux uses VGA/VESA for text
> > > mode console so that is going to be needed unless we have a Kernel
> > > driver for console mode.
> >
> > This seems like a good time for a reminder of the following. If the
> > system firmware wants to talk at say 640x480 but you have a fixed
> > frequency or limited multi-scan monitor that does not do 640x480,
> > the board needs to convert.
>
> Our video controller design doesn't provision for scaling.
Perhaps I'm misunderstanding something, but it looks to me like
you've gone from scaling to integer-only scaling to no scaling?
Well, for the moment.
I'm thinking about some future changes to the video controller to
support scaling:
Instead of reading pixels into a fifo, they're read into a scanline buffer.
There are two buffers that you can load.
When you SEND pixels, you can indicate how to weight the blending of
the two buffers, as well as horizontal stretch and blend.
We'll need registers to track the blending factors for modes that
don't have a small common denominator.
This way, you can scale up as much as you want and down by a factor of two.
Beyond a certain point, it becomes more cost-effective to throw out
the programmable design and just do a fixed register design that is
designed to do arbitrary scaling.
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