[coreboot] $7 cheap FT232H board as EHCI debug dongle for coreboot - would it work?

[Kyösti Mälkki]

On Mon, Mar 5, 2018 at 12:18 PM, Mike Banon <mikebdp2 at gmail.com> wrote:
> Hi Kyosti, Thank you very much for your reply!
>
> I will try to get a couple of these FT232H boards: perhaps just 1 is
> required for the successful setup, but these boards are not common
> (just 15 or 20 search results) so maybe its' a good idea to take 2 ;)
>

Not likely those PCBs have gone through much testing on assembly line,
how about 4...

> If this FT232H board works, it would be an ideal replacement both for
> commercial AMIDebug Rx / Ajays NET20DC (because much cheaper) and
> FX2LP (because no DIY will be required). Maybe this info could even be
> added to the official coreboot wiki, but I don't have an account there
> and it seems hard to get, so I'm using the DangerousPrototypes wiki
>

It won't become a compatible replacement, as you would need to modify
the (proprietary) software of both device-under-test and the host.
FT232H could be made to work with linux kernel early_printk=dbgp but I
don't think anyone has done that.

FX2LP approach was able to mimic the net20dc USB descriptors,
including the special response of debug feature and endpoint number
assignment.

> Will write an update when I'd get the boards and test them with AMD
> G505S laptop. I'm curious what Lenovo G505S is writing to the coreboot
> log while it boots

It writes just the same you get with cbmem -c utility, assuming you
can reach OS on the DUT.

Kyösti