linux-kernel - Re: [PATCH v2 1/2] tty: serial: print earlycon info after match->setup

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Date:   Fri, 18 Sep 2020 14:03:11 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Hsin-Yi Wang <hsinyi@...omium.org>
Cc:     "open list:SERIAL DRIVERS" <linux-serial@...r.kernel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Serge Semin <Sergey.Semin@...kalelectronics.ru>,
        Changqi Hu <changqi.hu@...iatek.com>,
        Frank Wunderlich <frank-w@...lic-files.de>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        linux-arm Mailing List <linux-arm-kernel@...ts.infradead.org>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-mediatek@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Enric Balletbo i Serra <enric.balletbo@...labora.com>,
        Eddie Huang <eddie.huang@...iatek.com>
Subject: Re: [PATCH v2 1/2] tty: serial: print earlycon info after match->setup

On Tue, Sep 15, 2020 at 8:50 AM Hsin-Yi Wang <hsinyi@...omium.org> wrote:
>
> 8250 devices may modify iotype in their own earlycon setup. For example:
> 8250_mtk and 8250_uniphier force iotype to be MMIO32. Print earlycon info
> after match->setup to reflect actual earlycon info.

Thanks for an update.
I prefer to see some flag that tells user that options were forced by
the kernel itself (something like err > 0 returned from ->setup()),
but I think it's matter of an additional fix. In principle user can
check the command line and / or DT/ACPI vs. dmesg, although it will
require an extra work.

> Signed-off-by: Hsin-Yi Wang <hsinyi@...omium.org>
> ---
> Change:
> v1->v2: rename function
> ---
>  drivers/tty/serial/earlycon.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/tty/serial/earlycon.c b/drivers/tty/serial/earlycon.c
> index 2ae9190b64bb9..b70877932d47d 100644
> --- a/drivers/tty/serial/earlycon.c
> +++ b/drivers/tty/serial/earlycon.c
> @@ -56,7 +56,6 @@ static void __init earlycon_init(struct earlycon_device *device,
>                                  const char *name)
>  {
>         struct console *earlycon = device->con;
> -       struct uart_port *port = &device->port;
>         const char *s;
>         size_t len;
>
> @@ -70,6 +69,12 @@ static void __init earlycon_init(struct earlycon_device *device,
>         len = s - name;
>         strlcpy(earlycon->name, name, min(len + 1, sizeof(earlycon->name)));
>         earlycon->data = &early_console_dev;
> +}
> +
> +static void __init earlycon_print_info(struct earlycon_device *device)
> +{
> +       struct console *earlycon = device->con;
> +       struct uart_port *port = &device->port;
>
>         if (port->iotype == UPIO_MEM || port->iotype == UPIO_MEM16 ||
>             port->iotype == UPIO_MEM32 || port->iotype == UPIO_MEM32BE)
> @@ -140,6 +145,7 @@ static int __init register_earlycon(char *buf, const struct earlycon_id *match)
>
>         earlycon_init(&early_console_dev, match->name);
>         err = match->setup(&early_console_dev, buf);
> +       earlycon_print_info(&early_console_dev);
>         if (err < 0)
>                 return err;
>         if (!early_console_dev.con->write)
> @@ -302,6 +308,7 @@ int __init of_setup_earlycon(const struct earlycon_id *match,
>         }
>         earlycon_init(&early_console_dev, match->name);
>         err = match->setup(&early_console_dev, options);
> +       earlycon_print_info(&early_console_dev);
>         if (err < 0)
>                 return err;
>         if (!early_console_dev.con->write)
> --
> 2.28.0.618.gf4bc123cb7-goog
>


-- 
With Best Regards,
Andy Shevchenko