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

Jiri Slaby (SUSE)
2025-06-11T10:04:00Z

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)
+ 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
--
2.49.0