Re: [PATCH] serial: sh-sci: optimize max_freq determination

[Geert Uytterhoeven]

Hi Hugo,

On Sat, 18 Apr 2026 at 07:24, Hugo Villeneuve <hugo@xxxxxxxxxxx> wrote:
> From: Hugo Villeneuve <hvilleneuve@xxxxxxxxxxxx>
>
> Follow example of rsci driver to avoid code duplication and useless
> max_freq search when port->uartclk is set to zero.
>
> Signed-off-by: Hugo Villeneuve <hvilleneuve@xxxxxxxxxxxx>

Thanks for your patch!

> --- a/drivers/tty/serial/sh-sci.c
> +++ b/drivers/tty/serial/sh-sci.c
> @@ -2711,14 +2711,15 @@ static void sci_set_termios(struct uart_port *port, struct ktermios *termios,
>          * setup the baud rate generator hardware for us already.
>          */
>         if (!port->uartclk) {
> -               baud = uart_get_baud_rate(port, termios, old, 0, 115200);
> -               goto done;

There was no "useless max_freq search", due to this goto?

> +               max_freq = 115200;
> +       } else {
> +               for (i = 0; i < SCI_NUM_CLKS; i++)
> +                       max_freq = max(max_freq, s->clk_rates[i]);
> +
> +               max_freq /= min_sr(s);
>         }
>
> -       for (i = 0; i < SCI_NUM_CLKS; i++)
> -               max_freq = max(max_freq, s->clk_rates[i]);
> -
> -       baud = uart_get_baud_rate(port, termios, old, 0, max_freq / min_sr(s));
> +       baud = uart_get_baud_rate(port, termios, old, 0, max_freq);
>         if (!baud)
>                 goto done;
>

Due to removing the goto above (for the casual reader: this is the
earlyprintk case, when port->uartclk is zero), the code will now
continue here, calculating transmission parameters and setting best_clk,
and overwriting the register configuration done by the bootloader.

Gr{oetje,eeting}s,

                        Geert

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

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