Serial console via USB (USBTTY) ...

[Andy Shevchenko]

On Thu, Apr 1, 2021 at 2:19 PM Herbert Poetzl <herbert at 13thfloor.at> wrote:
>
>
> I'm trying to get a serial console via USB working on
> STM32MP1 but I'm encountering some problems there ...
>
> The u-boot README suggests to add the following config
> entries to the board specific .h file:
>
>  CONFIG_USB_DEVICE
>  CONFIG_USB_TTY
>  CONFIG_USBD_HS (for high speed support)
>  CONFIG_SYS_CONSOLE_IS_IN_ENV
>
> ... but when doing so, I get a number of linker errors
> which suggest that there is something missing:
> https://pastebin.com/raw/bbpCu8jy
>
> Marek (via IRC) suggested that this is because the
> USB_TTY seems to be based on the old gadget framework
> and needs to be updated to the new one.

Precisely!

> It was also suggested that a port of the Linux serial
> function driver would be a good alternative to get
> CDC/ACM functionality into u-boot and that Andy might
> already be working on this ...

I abandoned that, but I can send what I have (it still doesn't
properly work to me).

> So my questions are:
>
>  - What is currently the best/easiest approach to
>    get a serial console via USB working?

Create a support for it. You may consider it as there is no support.

>  - Is the port from Linux in a stage that it can
>    be tested and/or finalized within a easonable
>    amount of time?

Not from me (I started but encountered so many issues here and there,
besides the fact that it's really time consuming).

>  - Can I help getting this working?

If you do it yourself. I can help with testing on my platform.

-- 
With Best Regards,
Andy Shevchenko