linux-kernel - Re: [PATCH V2 3/3] serial: stm32: add earlycon support

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Message-ID: <CAMuHMdVyScZaYPcRqcobnaC2LAdfV80KXzCnxwfBE9-Q+72OYQ@mail.gmail.com>
Date:   Thu, 14 Apr 2022 14:24:26 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Valentin CARON <valentin.caron@...s.st.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jonathan Corbet <corbet@....net>,
        Jiri Slaby <jirislaby@...nel.org>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        Erwan Le Ray <erwan.leray@...s.st.com>,
        "open list:SERIAL DRIVERS" <linux-serial@...r.kernel.org>,
        linux-stm32@...md-mailman.stormreply.com,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "open list:DOCUMENTATION" <linux-doc@...r.kernel.org>
Subject: Re: [PATCH V2 3/3] serial: stm32: add earlycon support

Hi Valentin,

On Thu, Apr 14, 2022 at 2:17 PM Valentin CARON
<valentin.caron@...s.st.com> wrote:
> On 4/11/22 16:59, Geert Uytterhoeven wrote:
> > On Fri, Apr 8, 2022 at 3:14 PM Valentin Caron
> > <valentin.caron@...s.st.com> wrote:
> >> Add early console support in stm32 uart driver.
> >>
> >> Signed-off-by: Alexandre Torgue <alexandre.torgue@...s.st.com>
> >> Signed-off-by: Valentin Caron <valentin.caron@...s.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?
>
> 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 ?

I think you should.  The less platform-specific kernel parameters,
the better. And the less bad examples to copy from.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-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