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References: <20220408122636.505737-1-valentin.caron@foss.st.com> <20220408122636.505737-4-valentin.caron@foss.st.com>
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From:   Geert Uytterhoeven <geert@linux-m68k.org>
Date:   Mon, 11 Apr 2022 16:59:13 +0200
Message-ID: <CAMuHMdWD8fxeqPUaT_CwnYdq02aaTsnQM_G-YyOGWooS5epCeQ@mail.gmail.com>
Subject: Re: [PATCH V2 3/3] serial: stm32: add earlycon support
To:     Valentin Caron <valentin.caron@foss.st.com>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jonathan Corbet <corbet@lwn.net>,
        Jiri Slaby <jirislaby@kernel.org>,
        Maxime Coquelin <mcoquelin.stm32@gmail.com>,
        Alexandre Torgue <alexandre.torgue@foss.st.com>,
        Erwan Le Ray <erwan.leray@foss.st.com>,
        "open list:SERIAL DRIVERS" <linux-serial@vger.kernel.org>,
        linux-stm32@st-md-mailman.stormreply.com,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        "open list:DOCUMENTATION" <linux-doc@vger.kernel.org>
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Hi Valentin,

On Fri, Apr 8, 2022 at 3:14 PM Valentin Caron
<valentin.caron@foss.st.com> wrote:
> Add early console support in stm32 uart driver.
>
> Signed-off-by: Alexandre Torgue <alexandre.torgue@foss.st.com>
> Signed-off-by: Valentin Caron <valentin.caron@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@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