Re: [Linux-fbdev-devel] Supporting various depth

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

On Wed, Jun 13, 2001 at 05:29:44PM +0200, Geert Uytterhoeven wrote:
> On Wed, 13 Jun 2001, Sven LUTHER wrote:
> > On Wed, Jun 13, 2001 at 03:49:41PM +0200, Geert Uytterhoeven wrote:
> > > On Wed, 13 Jun 2001, Romain Dolbeau wrote:
> > > > Is there a way to distinguish 15 and 16 bpp in 16bits pixels in
> > > > the fbdev/fbcon layer ?
> > > 
> > > Yes, by looking at the fb_var_screeninfo.{red,green,blue}.length fields.
> > > 
> > > > pm3fb support RGB565 in 16bpp, and I was just asked for 15bpp
> > > > (RGB555 + 1 bit Alpha or whatever). Do I simply reuse CFB16
> > > > and support both internally, is there a requirement that
> > > > CFB16 is one or the other, ... ?
> > > 
> > > Cfb16 is the memory organization: packed 16 bits per pixel. How a pixel looks
> > > like internally doesn't matter. So both RGB555 and RGB565 use fbcon-cfb16.c.
> > 
> > So i suppose saying fbset -depth 15 could be done to switch the fb to
> > RGBA5551 mode ? 
> 
> No, -depth actually means bits-per-pixel in fbset (yes this is a bug).

Ok, what about the fbdev driver silently converting bpp 15 to bpp 16 and
setting RGB5551 ?

Friendly,

Sven Luther