Re: [PATCH] fbdev: workaround for broken X servers

["Antonino A. Daplas" <adaplas@hotpop.com>]

On Friday 05 November 2004 20:15, Geert Uytterhoeven wrote:
> On Fri, 5 Nov 2004, Benjamin Herrenschmidt wrote:
> > > But every existing application that uses (shiver) the kernel headers
> > > will break after this change...
> >
> > Geert, can you explain the whole story please ?
>
> The story about the +1 or the story about the breakage?
>
> The Story About The +1
> ----------------------
> Since the VESA levels do not provide a way to blank (`make it black') the
> screen, the +1 is introduced. Hence 0 means unblank, 1 means black screen,
> 2 means lowest power save level, and so on...

And make it black is usually done in software (by memsetting the screen with
the black color).  

So why not this:  In fbcon_blank(), if the blank parameter is:

0 - unblank the screen, and call info->fbops->fb_blank(VESA_NO_BLANKING), 
     then return a nonzero value to force a redraw.
1,2,3,4 - clear the screen with all black
2,3,4 - call info->fbops->fb_blank(blank - 1);

Similarly, we can do the same thing in fbmem.c:fb_blank(), but without the software
blanking.

Drivers will just need to follow the VESA_* defines in fb.h (which happens to be also
defined in console.h)

Tony 




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