[PATCH V2 3/3] serial: stm32: add earlycon support

[Valentin CARON]

On 4/11/22 16:59, Geert Uytterhoeven wrote:
> Hi Valentin,
>
> On Fri, Apr 8, 2022 at 3:14 PM Valentin Caron
> <valentin.caron at foss.st.com> wrote:
>> Add early console support in stm32 uart driver.
>>
>> Signed-off-by: Alexandre Torgue <alexandre.torgue at foss.st.com>
>> Signed-off-by: Valentin Caron <valentin.caron at foss.st.com>
> Thanks for your patch!
>
>> --- a/Documentation/admin-guide/kernel-parameters.txt
>> +++ b/Documentation/admin-guide/kernel-parameters.txt
>> @@ -1264,6 +1264,12 @@
>>                          address must be provided, and the serial port must
>>                          already be setup and configured.
>>
>> +               stm32,<addr>
>> +                       Use early console provided by ST Microelectronics
>> +                       serial driver for STM32 SoCs. A valid base address
>> +                       must be provided, and the serial port must already
>> +                       be setup and configured.
> Why do you need this parameter?
>
> Given this driver uses DT, can't it figure out the serial port address
> from chosen/stdout-path?
>
> +OF_EARLYCON_DECLARE(stm32, "st,stm32h7-uart", early_stm32_h7_serial_setup);
> +OF_EARLYCON_DECLARE(stm32, "st,stm32f7-uart", early_stm32_f7_serial_setup);
> +OF_EARLYCON_DECLARE(stm32, "st,stm32-uart", early_stm32_f4_serial_setup);
>
> Gr{oetje,eeting}s,
>
>                          Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at linux-m68k.org
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                  -- Linus Torvalds

Hi Geert,

I took the example of other serial drivers.
Both methods work (with earlycon/stdout-path and with 
earlycon=stm32,0xXXXXXXX)
but your right, the second will probably never used on this driver.

Should I remove it ?

Thanks,
Valentin