On Thu, 2002-07-25 at 08:50, Dr Andrew C Aitchison wrote:
> On Wed, 24 Jul 2002, hy0 wrote:
>
> > > Actually, the value of this option is processed in this switch
> > > statement:
> > >
> > > switch (info->agpMode) {
> > > case 4: mode |= RADEON_AGP_4X_MODE;
> > > case 2: mode |= RADEON_AGP_2X_MODE;
> > > case 1: default: mode |= RADEON_AGP_1X_MODE;
> > > }
> > >
> > > As you can see, anything except 2 and 4 will set 1x. Even 4 and 2 may
> > > fall back to lower transfer rates depending on the capabilities of the
> > > chip and the AGP bridge. agpgart handles that.
> >
> > There is no break in above switch statement. 3 LSBs will fall through.
> > If agpMode=7, 7 will be passed to the agpgart driver. This is not a bug,
> > agpgart driver
> > (see agpgart_be.c) will use the highest bit according to AGP bridge's
> > capability.
> > That's why I said if you use AGPMode = 3, you'll end up with 2x.
>
> There is no beak, but there is no fall through for 7 or 3:
> agpMode mode
> 7 1
> 6 1
> 5 1
> 4 7
> 3 1
> 2 3
> 1 1
Exactly, and then agpgart picks the highest set bit from mode which is
supported by the chip and the bridge.
--
Earthling Michel D�nzer (MrCooper)/ Debian GNU/Linux (powerpc) developer
XFree86 and DRI project member / CS student, Free Software enthusiast
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