[coreboot] Intel i855pm northbridge

Uwe Hermann uwe at hermann-uwe.de
Sun Oct 5 02:44:51 CEST 2008

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. 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.

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