linux-kernel - [PATCH 19/33] serial: 8250: extract serial8250_set_trigger_for_slow

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Message-ID: <20250611100319.186924-20-jirislaby@kernel.org>
Date: Wed, 11 Jun 2025 12:03:05 +0200
From: "Jiri Slaby (SUSE)" <jirislaby@...nel.org>
To: gregkh@...uxfoundation.org
Cc: linux-serial@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	"Jiri Slaby (SUSE)" <jirislaby@...nel.org>
Subject: [PATCH 19/33] serial: 8250: extract serial8250_set_trigger_for_slow_speed()

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@...nel.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