Re: [PATCH v3 2/3] serial: sh-sci: Drop check for zero baud rate from uart_get_baud_rate()

[Hugo Villeneuve]

On Wed, 22 Apr 2026 10:05:38 -0400
Hugo Villeneuve <hugo@xxxxxxxxxxx> wrote:

> Hi,
> 
> On Wed, 22 Apr 2026 10:59:23 +0200
> Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote:
> 
> > Hi Biju,
> > 
> > On Wed, 22 Apr 2026 at 09:26, Biju Das <biju.das.jz@xxxxxxxxxxxxxx> wrote:
> > > > From: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
> > > > On Mon, 20 Apr 2026 at 16:04, Biju <biju.das.au@xxxxxxxxx> wrote:
> > > > > From: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
> > > > >
> > > > > On DT systems, a zero baud rate from uart_get_baud_rate() is not
> 
> The fact that uart_get_baud_rate() cannot return zero is not related
> to the system using DT or not, so I would drop this "On DT systems, "
> from the commit message.
> 
> > > > > possible even earlycon derives its bit rate from chosen/stdout-path.
> > > > > The zero baud guard and its associated done label are therefore dead code. So remove it.
> > > > >
> > > > > Also drop the unused done label from rsci_set_termios().
> > > > >
> > > > > Signed-off-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
> > > >
> > > > > --- a/drivers/tty/serial/sh-sci.c
> > > > > +++ b/drivers/tty/serial/sh-sci.c
> > > > > @@ -2719,8 +2719,6 @@ static void sci_set_termios(struct uart_port *port, struct ktermios *termios,
> > > > >                 max_freq = max(max_freq, s->clk_rates[i]);
> > > > >
> > > > >         baud = uart_get_baud_rate(port, termios, old, 0, max_freq / min_sr(s));
> > > > > -       if (!baud)
> > > > > -               goto done;
> > > > >
> > > > >         /*
> > > > >          * There can be multiple sources for the sampling clock.  Find
> > > > > the one
> > > >
> > > > I am afraid you are missing that sh-sci is also used on SH, without DT?
> > >
> > > Ok, please share your thoughts to handle divide_by_zero fault for
> > > SH platforms on the code path after done label??
> > 
> > Someone has to check on an SH platform (or qemu rts7751r2d) if
> > this can happen. It might have been broken along the road, as people
> > only use earlyprintk when debugging a problem that requires it.
> 
> Geert: this "goto done" is not related to the earlyprintk block, which
> is untouched by this patch?

Hi Biju,
I cannot see any follow-up for these patches. My series for "serial:
core: improve safety of uart_get_baud_rate()" has been accepted and
integrated, so now the renesas sh-sci and rsci are the only drivers
still checking (for nothing) the zero return value of
uart_get_baud_rate().

I plan on sending two patches to address only that for sh-sci and rsci,
unless you are preparing a new serie that includes it?

Hugo.