tdfx's use of PIOOffset

[Michael]

Hello,

On Wed, 19 Oct 2011 00:53:55 -0700
Jeremy Huddleston <jeremyhu at apple.com> wrote:

> So the tdfx driver has this hunk of code in it currently does the following:
> 
> #if USE_PCIVGAIO
>   hwp->PIOOffset = pTDFX->PIOBase[0] - 0x300;
> #endif
> 
> Can someone please explain to me why it's doing that?

On this particular chip the legacy VGA registers are mapped by the IO BAR instead of getting special treatment.

have fun
Michael