[GSoC] Console via SMBus

[Ahamed Husni]

Hi everyone,

I would like to work with bringing up the Console via SMBus project [1].

This project requires a mainboard with pluggable RAM for the development
so that we can use a RAM breakout board [2] to access the SMBus interface.
Preferably the mainboard should already support coreboot.

Please add your thoughts and concerns about the project and suggest a
mainboard for the project :)

[1] https://www.coreboot.org/Project_Ideas#console_via_SMBus
[2] https://www.joom.com/en/products/5fa9df2ea1684001068ec310

Thank you,
Husni.

[Peter Stuge]

Ahamed Husni wrote:
> Please add your thoughts and concerns about the project and suggest a
> mainboard for the project :)

You're correct that socketed RAM is important for the project;
mainboards with onboard RAM usually have no SPD memory at all,
so the SMBus may not be at all accessible.

Any particular mainboard might not be so important as long as the
SMBus can be accessed somewhere; possibly a cellphone repair store
can help solder the three SMBus wires to a small connector for the
purpose of the project.

But it would be great to also consider what the user story is for
people who want to use this on other mainboards.

Ideally it shouldn't be neccessary to buy a niche product like a RAM
breakout adapter; it would be great to also explore more ways to
access the SMBus signals, e.g. PCI Express optionally has SMBus,
smart batteries have it, etc.

Kind regards

//Peter

[Ahamed Husni]

Hello Peter,

Thank you for your email.

On Fri, Apr 1, 2022 at 6:41 PM Peter Stuge  wrote:
> But it would be great to also consider what the user story is for
> people who want to use this on other mainboards.
>
> Ideally it shouldn't be neccessary to buy a niche product like a RAM
> breakout adapter; it would be great to also explore more ways to
> access the SMBus signals, e.g. PCI Express optionally has SMBus,
> smart batteries have it, etc.

The VGA and HDMI interfaces also use the SMBus.
Theoretically we should be able to use a VGA[3] cable and expose
the wires of pins 12(SDA) and 15(SCL) to access the bus.
I can test that proof of concept if I complete the project earlier
than expected.

[3] https://en.wikipedia.org/wiki/VGA_connector

Thanks,
Husni.