[NEW FEATURE] RFC: Add Intel GMBUS support

[Bin Meng]

+Simon

Hi Eric,

On Fri, Sep 22, 2023 at 6:10 AM Eric Schikschneit
<eric.schikschneit at novatechautomation.com> wrote:
>
> I have begun working on adding support for the Intel Graphics Management bus to U-Boot. Currently the x86 bring up process (as explored on the Baytrail series of Atom SOCs) relys on the Intel Video BIOS to do all setup and configuration of the GPU. This method of adding video support works on earlier versions of the silicon. With later versions I have found that the OEM BIOS needs to capture the monitor data over the GMBUS in order to initialize the GPU properly. I have logic analyzer captures available for anyone who is curious. My purpose for this patch is a skeleton placeholder that I will be working from, and I am asking for community collaboration with this. I have hardware available for testing as needed, and some details can be provided upon request.

Would you share the documentation that describes the Intel GM bus, if
publicly available?

Based on the info you provided, did you mean with later new revision
BayTrail chips, the video bios initialization is not enough in U-Boot?
AFAIU, the U-Boot BayTrail support relies on Intel FSP to do any
chipset-specific work, including the video bios setup.

Regards,
Bin