Serial console via USB (USBTTY) ...

[Andy Shevchenko]

On Thu, Apr 1, 2021 at 7:17 PM Herbert Poetzl <herbert at 13thfloor.at> wrote:
>
>
> Hello Andy!
>
> Thanks for the quick feedback!
>
> On Thu, Apr 01, 2021 at 04:10:57PM +0300, Andy Shevchenko wrote:
> > 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!
>
> Are there any examples of such a conversion or is there
> some guide how to convert drivers from the 'old' framework
> to the 'new' one?
>
> >> 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).
>
> Would definitely be interesting to see, as it seems that
> other function drivers (those are the f_* ones, as far
> as I understood) seem to work just fine.

Here you are: https://github.com/andy-shev/u-boot/tree/topic/f-serial

No guarantees or anything. It's a pile of something.
Tell me when you get it, so I will remove the branch (let's say I'll
do it within 24 hours anyway).

> >> 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.
>
> Okay, how do I best start with that?

Try to read the code of existing functions in U-Boot and Linux kernel?

> >>  - 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).
>
> I understand ...
>
> >>  - Can I help getting this working?
>
> > If you do it yourself. I can help with testing on my platform.
>
> Great! Thanks in advance!



>
> Best,
> Herbert
>
> > --
> > With Best Regards,
> > Andy Shevchenko



-- 
With Best Regards,
Andy Shevchenko