RE: [PATCH v3 3/3] serial: rsci: Refactor baud rate clock selection

[Biju Das]

Hi All,

> -----Original Message-----
> From: Biju <biju.das.au@xxxxxxxxx>
> Sent: 20 April 2026 15:04
> Subject: [PATCH v3 3/3] serial: rsci: Refactor baud rate clock selection
> 
> From: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
> 
> Since RSCI only uses a single clock source (SCI_FCK), the multi-clock tracking variables (best_clk,
> min_err, brr1, srr1, cks1) are redundant and removed. ccr0_val and ccr4_val are likewise dropped,
> replaced with hardcoded 0 at their write sites, as they were never modified from their initial zero
> values.
> 
> No functional change intended.
> 
> Signed-off-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
> ---
> v2->v3:
>  * Dropped reported by tag as the goto statement in rsci_set_termios()
>    removed in the previous patch.
>  * baud check removed by previous patch.
>  * Added missing macro CCR0_RE while dropping ccr0_val variable.
>  * Updated commit description.
> v1->v2:
>  * Dropped the check (abs(err) < abs(min_err) as it is always true.
>  * Dropped the check (abs(err) < abs(min_err) as it is always true.
>  * Dropped variables best_clk and min_err as they are no longer needed.
>  * Dropped intermediate variables brr1, cks1 and srr1; results are now
>    written directly into brr, cks and srr.
>  * Moved dev_dbg() inside the if (baud) block.
>  * Dropped ccr0_val and ccr4_val, replaced with hardcoded 0 at their
>    write sites, as they were never modified from their initial values.
>  * Scoped variables err and srr locally within the if (baud) block.
>  * Updated commit description.
> ---
>  drivers/tty/serial/rsci.c | 31 ++++++++++---------------------
>  1 file changed, 10 insertions(+), 21 deletions(-)
> 
> diff --git a/drivers/tty/serial/rsci.c b/drivers/tty/serial/rsci.c index 40db9daa4272..444e89696310
> 100644
> --- a/drivers/tty/serial/rsci.c
> +++ b/drivers/tty/serial/rsci.c
> @@ -217,16 +217,15 @@ static void rsci_set_termios(struct uart_port *port, struct ktermios *termios,
>  			     const struct ktermios *old)
>  {
>  	unsigned int ccr2_val = CCR2_INIT, ccr3_val = CCR3_INIT;
> -	unsigned int ccr0_val = 0, ccr1_val = 0, ccr4_val = 0;
> -	unsigned int brr1 = 255, cks1 = 0, srr1 = 15;
>  	struct sci_port *s = to_sci_port(port);
>  	unsigned int brr = 255, cks = 0;
> -	int min_err = INT_MAX, err;
> -	unsigned long max_freq = 0;
> +	unsigned int ccr1_val = 0;
> +	unsigned long max_freq;

This needs to be initialized to 0. Otherwise it will compare with 
uninitialized stack value on else path.

max_freq = max(max_freq, s->clk_rates[i]);


>  	unsigned int baud, i;
>  	unsigned long flags;
>  	unsigned int ctrl;
> -	int best_clk = -1;
> +	unsigned int srr;

Also, looks this needs to be initialized to 15, when we drop srr1.

sci_scbrr_calc() fails, It will print uninitialized value

Cheers,
Biju