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SubjectRe: [PATCH] serial: earlycon: prefer EARLYCON_DECLARE() variant
Hi Greg,


Am 2020-02-20 18:46, schrieb Michael Walle:
> If a driver exposes early consoles with EARLYCON_DECLARE() and
> OF_EARLYCON_DECLARE(), pefer the non-OF variant if the user specifies
> it
> by
> earlycon=<driver>,<options>
>
> The rationale behind this is that some drivers register multiple setup
> functions under the same driver name. Eg.
>
> OF_EARLYCON_DECLARE(lpuart, "fsl,vf610-lpuart",
> lpuart_early_console_setup);
> OF_EARLYCON_DECLARE(lpuart32, "fsl,ls1021a-lpuart",
> lpuart32_early_console_setup);
> OF_EARLYCON_DECLARE(lpuart32, "fsl,imx7ulp-lpuart",
> lpuart32_imx_early_console_setup);
> EARLYCON_DECLARE(lpuart, lpuart_early_console_setup);
> EARLYCON_DECLARE(lpuart32, lpuart32_early_console_setup);
>
> It depends on the order of the entries which console_setup() actually
> gets called. To make things worse, I guess it also depends on the
> compiler how these are ordered. Thus always prefer the
> EARLYCON_DECLARE()
> ones.

Do you have an opinon on this proposal?

-michael

>
> Signed-off-by: Michael Walle <michael@walle.cc>
> ---
> drivers/tty/serial/earlycon.c | 11 +++++++++++
> 1 file changed, 11 insertions(+)
>
> diff --git a/drivers/tty/serial/earlycon.c
> b/drivers/tty/serial/earlycon.c
> index c14873b67803..2ae9190b64bb 100644
> --- a/drivers/tty/serial/earlycon.c
> +++ b/drivers/tty/serial/earlycon.c
> @@ -170,6 +170,7 @@ static int __init register_earlycon(char *buf,
> const struct earlycon_id *match)
> int __init setup_earlycon(char *buf)
> {
> const struct earlycon_id **p_match;
> + bool empty_compatible = true;
>
> if (!buf || !buf[0])
> return -EINVAL;
> @@ -177,6 +178,7 @@ int __init setup_earlycon(char *buf)
> if (early_con.flags & CON_ENABLED)
> return -EALREADY;
>
> +again:
> for (p_match = __earlycon_table; p_match < __earlycon_table_end;
> p_match++) {
> const struct earlycon_id *match = *p_match;
> @@ -185,6 +187,10 @@ int __init setup_earlycon(char *buf)
> if (strncmp(buf, match->name, len))
> continue;
>
> + /* prefer entries with empty compatible */
> + if (empty_compatible && *match->compatible)
> + continue;
> +
> if (buf[len]) {
> if (buf[len] != ',')
> continue;
> @@ -195,6 +201,11 @@ int __init setup_earlycon(char *buf)
> return register_earlycon(buf, match);
> }
>
> + if (empty_compatible) {
> + empty_compatible = false;
> + goto again;
> + }
> +
> return -ENOENT;
> }

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