[coreboot] [PATCH] Implement DRAM buffer strength programming for 440BX

Keith Hui buurin at gmail.com
Sun Mar 14 06:02:53 CET 2010

> > Below are debug outputs of my new RAM init code. As you can see it
> > isn't quite working. Can this output help in finding out why?
> No. You'll have to run a diff between the old (working?) and the new
> code and do a binary search over the changes to find out what's causing
> the trouble.
> Stefan

Thank you!

With your hint, I realized that I have made too many changes at once and
will have to make and test them one by one instead.

The result is this patch. It implements a full SDRAM buffer strength
programming algorithm in set_dram_buffer_strength(), checked against my
P2B-LS factory BIOS. With this in place, I now have 133MHz (!) stability
with three 256MB PC133 modules, and can boot Fedora 11 all the way to the
init daemon (actually upstart, but that's another story). Not to login
prompt yet. We'll find out why later.

This again assumes a 4-DIMM board because that's all I have. I need someone
with a 3-DIMM board to test it.

As a bonus, there's a big comment block within that illustrates the
algorithm. :-)

Signed-off-by: Keith Hui <buurin at gmail.com>
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