[coreboot] Intel i855pm northbridge

[Corey Osgood]

On Sat, Oct 4, 2008 at 8:44 PM, Uwe Hermann <uwe at hermann-uwe.de> wrote:

> On Sun, Oct 05, 2008 at 01:27:01AM +0200, Vincent Legoll wrote:
> > I'm trying to understand i855pm code, and reading reset_test.c, I see:
> > #define MCH_DRC 0x70
> >
> > whereas the 252613.pdf I downloaded from intel web site, at:
> > http://www.intel.com/Assets/PDF/datasheet/252613.pdf
> > "Intel(R) 855PM Chipset Memory Controller Hub (MCH) DDR 200/266 MHz
> Datasheet"
> > revision 003, page 71, has the following:
> >
> > 3.7.20. DRC – DRAM Controller Mode Register – Device #0
> > Offset:             7C-7Fh
> > Default:            1000_0001h
> > Access:             Read/Write
> > Size:               32 bits
> >
> > So what am I missing in the 0x70h versus 0x7Ch difference ?
> >
> > Could someone please gently enlighten me ?
>
> Looks like a typo to me, I guess in the code, but it could also be in
> the datasheet.
>
> Be careful with the 855pm code though, I think it's unfinished and
> possibly never ever worked.


My understanding is that it's mostly a straight copy of and old version of
i440bx that was somewhat fixed up but never completed. I'd avoid it like the
plague. I'm pretty sure I requested removing it at one point, but it must
have been shot down.

-Corey


> If you really plan to add support for some
> newer Intel chipsets (which is not a small project mind you), I'd start
> with the i3100 code, which is in good shape quality-wise and has been
> confirmed working on hardware.
>
>
> Uwe.
> --
> http://www.hermann-uwe.de  | http://www.holsham-traders.de
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>
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