Re: [PATCH 20/33] serial: 8250: extract serial8250_set_afe()

Ilpo Järvinen
2025-06-11T12:35:20Z

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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 MCR for UART_CAP_AFE ports.
>
> Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
> ---
> drivers/tty/serial/8250/8250_port.c | 32 +++++++++++++++--------------
> 1 file changed, 17 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
> index 52385314c426..b15371838366 100644
> --- a/drivers/tty/serial/8250/8250_port.c
> +++ b/drivers/tty/serial/8250/8250_port.c
> @@ -2704,6 +2704,22 @@ static void serial8250_set_trigger_for_slow_speed(struct uart_port *port, struct
> up->fcr |= UART_FCR_TRIGGER_1;
> }
>
> +/*
> + * MCR-based auto flow control. When AFE is enabled, RTS will be deasserted when the receive FIFO
> + * contains more characters than the trigger, or the MCR RTS bit is cleared.
> + */
> +static void serial8250_set_afe(struct uart_port *port, struct ktermios *termios)
> +{
> + struct uart_8250_port *up = up_to_u8250p(port);
> +
> + if (!(up->capabilities & UART_CAP_AFE))
> + return;
> +
> + up->mcr &= ~UART_MCR_AFE;
> + if (termios->c_cflag & CRTSCTS)
> + up->mcr |= UART_MCR_AFE;
> +}
> +
> void
> serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios,
> const struct ktermios *old)
> @@ -2729,21 +2745,7 @@ serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios,
>
> up->lcr = cval; /* Save computed LCR */
> serial8250_set_trigger_for_slow_speed(port, termios, baud);
> -
> - /*
> - * MCR-based auto flow control. When AFE is enabled, RTS will be
> - * deasserted when the receive FIFO contains more characters than
> - * the trigger, or the MCR RTS bit is cleared.
> - */
> - if (up->capabilities & UART_CAP_AFE) {
> - up->mcr &= ~UART_MCR_AFE;
> - if (termios->c_cflag & CRTSCTS)
> - up->mcr |= UART_MCR_AFE;
> - }
> -
> - /*
> - * Update the per-port timeout.
> - */
> + serial8250_set_afe(port, termios);
> uart_update_timeout(port, termios->c_cflag, baud);
>
> /*
>

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

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