Display optimization

[Jim Gettys]

On Wed, 2006-10-11 at 00:57 +0200, Bert Freudenberg wrote:
> Hi folks,
> 
> I just read again that the display does "about 800×600 in color  
> mode". However, from the prototype I got the impression that "color  
> mode" means not much more than switching the backlight on, right? 

No, it involves deswizzling and AA.

> The  
> frame-buffer will still be 1200x900. 

Yes, we'll always run in 1200x900 in the frame buffer.

> Also I think someone mentioned  
> there is no video scaling hardware, just the optional anti-aliasing  
> in color mode.

Incorrect: the geode has both YUV->RGB and scaling hardware.

> 
> So am I right in assuming that from the software's pov, it doesn't  
> really matter, X will always run at 1200x900x16? Has it been decided  
> if it will be 5-6-5 or 4-4-4-4, yet? Or is that configurable?
16 bits for sure.
Haven't decided for certain about 565 versus 4444.
> 
> For optimal speed I'd like to avoid pixmap conversion, so what is the  
> fastest way to get bits to the screen? Is there a way to get direct  
> frame buffer access, or is XSHM the way to go, or something  
> completely different?

You can clock the difference between UNIX domain sockets and XSHM; some
apps it won't be significant, despite predictions to the contrary in
advance.  Sockets on Linux are wicked fast.
                                - Jim

> 
> - Bert -
> 
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-- 
Jim Gettys
One Laptop Per Child