linux-kernel - [PATCH v4 3/5] serial/8250: Use tx_loadsz as the transmitter fifo size

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Message-Id: <20220316143646.13301-4-wander@redhat.com>
Date:   Wed, 16 Mar 2022 11:36:42 -0300
From:   Wander Lairson Costa <wander@...hat.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>,
        Wander Lairson Costa <wander@...hat.com>,
        Johan Hovold <johan@...nel.org>,
        "Maciej W. Rozycki" <macro@...am.me.uk>,
        Lukas Wunner <lukas@...ner.de>,
        Pali Rohár <pali@...nel.org>,
        linux-serial@...r.kernel.org (open list:SERIAL DRIVERS),
        linux-kernel@...r.kernel.org (open list)
Cc:     rostedt@...dmis.org, senozhatsky@...omium.org,
        andre.goddard@...il.com, sudipm.mukherjee@...il.com,
        andy.shevchenko@...il.com, David.Laight@...lab.com,
        jonathanh@...dia.com, phil@...pberrypi.com
Subject: [PATCH v4 3/5] serial/8250: Use tx_loadsz as the transmitter fifo size

Using port_fifosize as the fifo size to transmit data to the serial
console causes data loss in some controllers. Use the correct tx_loadsz
field.

Thanks to Jon Hunter for reporting the issue.

Reported-by: Jon Hunter <jonathanh@...dia.com>
Tested-by: Jon Hunter <jonathanh@...dia.com>
Fixes: 5021d709b31b ("tty: serial: Use fifo in 8250 console driver")
Signed-off-by: Wander Lairson Costa <wander@...hat.com>
---
 drivers/tty/serial/8250/8250_port.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 9f3fa9fe2a4e..d3a93e5d55f7 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -3343,7 +3343,7 @@ static void serial8250_console_fifo_write(struct uart_8250_port *up,
 {
 	int i;
 	const char *end = s + count;
-	unsigned int fifosize = up->port.fifosize;
+	unsigned int fifosize = up->tx_loadsz;
 	bool cr_sent = false;
 
 	while (s != end) {
@@ -3409,7 +3409,7 @@ void serial8250_console_write(struct uart_8250_port *up, const char *s,
 	}
 
 	use_fifo = (up->capabilities & UART_CAP_FIFO) &&
-		port->fifosize > 1 &&
+		up->tx_loadsz > 1 &&
 		(up->fcr & UART_FCR_ENABLE_FIFO) &&
 		/*
 		 * After we put a data in the fifo, the controller will send
-- 
2.35.1