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

[Biju Das]

Hi Hugo,

> -----Original Message-----
> From: Hugo Villeneuve <hugo@xxxxxxxxxxx>
> Sent: 17 April 2026 20:36
> Subject: [PATCH] serial: sh-sci: optimize max_freq determination
> 
> 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>
> ---
> Cc: biju.das.jz@xxxxxxxxxxxxxx
> 
> Biju: if you want, feel free to pickup this patch when you resubmit your serie for "sh-sci/rsci: Fix
> divide by zero and clean up baud rate logic".
> ---
>  drivers/tty/serial/sh-sci.c | 13 +++++++------
>  1 file changed, 7 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c index
> 6c819b6b24258..dcee8b69adab2 100644
> --- 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;
> +		max_freq = 115200;

I have thought about this change. but the below comment made me not to do this change.

<snippet from Geert>
IIRC, baud == 0 can (only?) happen when using earlyprintk on a non-DT
system, where the serial console should just keep on using the settings
programmed by the firmware.  So any config register writes should
be skipped.
</snippet>

Cheers,
Biju

> +	} 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;
> 
> 
> base-commit: a1a81aef99e853dec84241d701fbf587d713eb5b
> --
> 2.47.3