[coreboot] about Ivy Bridge CPU with QM67 PCH

Iru Cai mytbk920423 at gmail.com
Fri Oct 23 13:31:59 CEST 2015


On Sun, Oct 18, 2015 at 06:44:09PM +0200, Peter Stuge wrote:
> Hi,
> Iru Cai wrote:
> > I've been testing the Lenovo T420 port recently, and now I can
> > install an Ivy Bridge processor and run fine on Linux(except some
> > thermal issues).
> That's pretty nice I think.
> > However, the native graphics initialization doesn't work properly
> ..
> > I don't know if someone has tried using mixed generation of CPU and
> > chipset combination with coreboot before,
> Probably not.
I finally found it's lvds_num_lanes in devicetree.cb that breaks
native graphics initilization, because SNB and IVB use different values.
And it has been solved in this upstream commit:

commit c48f5ef3cc623a4b1bccdbc9cb3e1d15505b7ad4
Author: Vladimir Serbinenko <phcoder at gmail.com>
Date:   Sun Oct 11 02:05:55 2015 +0200

    Kill lvds_num_lanes

    Only one value would work with corresponding gma code currently (which one
    depends on board). Going forward, it's possible to compute which number can
    be used, so there is no need to keep this info around.

Thank you Vladimir Serbinenko.

> > I have pushed the patch that makes coreboot support both SNB and
> > IVB processor for review:
> > http://review.coreboot.org/#/c/12087/
> Thanks! There is a source code style issue - you used two spaces
> instead of one tab to indent - please fix that, but other than that
> the patch looks fine to me.
> But the two files gma_{sandy,ivy}bridge_lvds.c are a bit of a mess -
> they need to be cleaned up and can quite easily be unified into a
> single file, without having it become the mess that the i915 kernel
> code is. The key is to have a good data model, and the data model
> seems clear to me from the existing code.
> For fun (or pain), take a look at: git diff 758a41 7137c5
> (sandy..ivy)
> //Peter
> -- 
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Iru Cai
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