On Fri, 5 Mar 2004, Thomas Winischhofer wrote:
> David Dawes wrote:
> > On Fri, Mar 05, 2004 at 01:38:06AM +0100, Thomas Winischhofer wrote:
> >>What exactly does a video driver have to be able to do if the
> >>SupportConvert32to24 flag is set at calling xf86SetDepthBpp, provided
> >>the hardware supports, for instance, 24bpp (framebuffer depth) only?
> >
> >
> > It has to use a framebuffer layer that can do this conversion. fb
> > can, as can xf24_32bpp (if your driver uses cfb). The s3virge
> > driver is an example that can still be run with the xf24_32bpp
> > method, and it does the following to figure out what to load:
> >
> > case 24:
> > if (pix24bpp == 24) {
> > mod = "cfb24";
> > reqSym = "cfb24ScreenInit";
> > } else {
> > mod = "xf24_32bpp";
> > reqSym = "cfb24_32ScreenInit";
> > }
> >
> > Most drivers use fb these days, and it has support for this built-in,
> > and enabled automatically.
>
> So it is save just to set these, I assume (since my driver uses fb).
> (Just wondered why the *driver* and not the layer taking care of this
> has to (not) set these.)
Do you mean the flag? The layer above does not know whether
or not the driver/HW supports a 24 bpp framebuffer. The "nv" driver,
for example, does not.
Mark.
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