Re: [Linux-fbdev-devel] Re: FBdev updates.

[Sven L. <lu...@dp...>]

On Thu, Mar 06, 2003 at 04:05:32PM +0800, Antonino Daplas wrote:
> On Thu, 2003-03-06 at 15:35, Sven Luther wrote:
> > >  
> > > >   And one (or two...) generic questions: why is not pseudo_palette
> > > > u32* pseudo_palette, or even directly u32 pseudo_palette[17] ?
> > > 
> > > pseudo_palette was originally designed to be a pointer to some kind of 
> > > data for color register programming. For example many PPC graphics cards 
> > > have a color register region. Now you could have that point to 
> > 
> > Does this correspond to the LUT i have in my boards ?
> > 
> > BTW, what is the point in having a pseudo_palette if you can store
> > the colors in the onchip LUT table.
> > 
> 
> The hardware clut typically stores each color channel separately.  In
> software terms, this is akin to struct fb_cmap.  The pseudo_palette, on
> the other hand, is a pixel LUT, the contents of which can be directly
> written to the framebuffer without it ever knowing the format at all, ie
> it does not matter if it's RGB or YUV.  This makes the upper layer
> independent of the low-lever driver (at least in terms of colorspace
> formats).

Ok, thanks, ...

Friendly,

Sven Luther