Re: [PATCH 19/33] serial: 8250: extract serial8250_set_trigger_for_slow_speed()

Ilpo Järvinen
2025-06-11T12:34:21Z

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On Wed, 11 Jun 2025, Jiri Slaby (SUSE) wrote:

> serial8250_do_set_termios() consists of many registers and up flags
> settings. Extract all these into separate functions. This time, setting
> of trigger level for slow speeds.
>
> Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
> ---
> drivers/tty/serial/8250/8250_port.c | 26 +++++++++++++++++++-------
> 1 file changed, 19 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
> index edfbaa6b7a1b..52385314c426 100644
> --- a/drivers/tty/serial/8250/8250_port.c
> +++ b/drivers/tty/serial/8250/8250_port.c
> @@ -2686,6 +2686,24 @@ static void serial8250_set_mini(struct uart_port *port, struct ktermios *termios
> }
> }
>
> +static void serial8250_set_trigger_for_slow_speed(struct uart_port *port, struct ktermios *termios,
> + unsigned int baud)
> +{
> + struct uart_8250_port *up = up_to_u8250p(port);
> +
> + if (!(up->capabilities & UART_CAP_FIFO))
> + return;
> + if (port->fifosize <= 1)
> + return;
> + if (baud >= 2400)
> + return;
> + if (up->dma)

Nit, I'd have put the DMA check before the speed check.

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

> + return;
> +
> + up->fcr &= ~UART_FCR_TRIGGER_MASK;
> + up->fcr |= UART_FCR_TRIGGER_1;
> +}
> +
> void
> serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios,
> const struct ktermios *old)
> @@ -2710,13 +2728,7 @@ serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios,
> uart_port_lock_irqsave(port, &flags);
>
> up->lcr = cval; /* Save computed LCR */
> -
> - if (up->capabilities & UART_CAP_FIFO && port->fifosize > 1) {
> - if (baud < 2400 && !up->dma) {
> - up->fcr &= ~UART_FCR_TRIGGER_MASK;
> - up->fcr |= UART_FCR_TRIGGER_1;
> - }
> - }
> + serial8250_set_trigger_for_slow_speed(port, termios, baud);
>
> /*
> * MCR-based auto flow control. When AFE is enabled, RTS will be
>

--
i.