Serial console via USB (USBTTY) ...
Herbert Poetzl
herbert at 13thfloor.at
Thu Apr 1 20:45:16 CEST 2021
On Thu, Apr 01, 2021 at 07:36:14PM +0300, Andy Shevchenko wrote:
> 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).
Got it, thanks!
>>>> 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?
Yeah, is there a specific function driver which was ported
from Linux to U-Boot already or would the serial driver
be the first one?
>>>> - 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!
Thanks a bunch,
Herbert
>> Best,
>> Herbert
>>> --
>>> With Best Regards,
>>> Andy Shevchenko
> --
> With Best Regards,
> Andy Shevchenko
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