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From: Wander Lairson Costa <wander@redhat.com>
To: "Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	"Jiri Slaby" <jirislaby@kernel.org>,
	"Johan Hovold" <johan@kernel.org>,
	"Wander Lairson Costa" <wander@redhat.com>,
	"Maciej W. Rozycki" <macro@orcam.me.uk>,
	"Serge Semin" <fancer.lancer@gmail.com>,
	"Lukas Wunner" <lukas@wunner.de>, "Pali Rohár" <pali@kernel.org>,
	linux-serial@vger.kernel.org (open list:SERIAL DRIVERS),
	linux-kernel@vger.kernel.org (open list)
Cc: rostedt@goodmis.org, senozhatsky@chromium.org,
	andre.goddard@gmail.com, sudipm.mukherjee@gmail.com,
	andy.shevchenko@gmail.com, David.Laight@aculab.com,
	jonathanh@nvidia.com, phil@raspberrypi.com
Subject: [PATCH v4 2/5] serial/8250: Use the cache value of the FCR register
Date: Wed, 16 Mar 2022 11:36:41 -0300	[thread overview]
Message-ID: <20220316143646.13301-3-wander@redhat.com> (raw)
In-Reply-To: <20220316143646.13301-1-wander@redhat.com>

commit 5021d709b31b ("tty: serial: Use fifo in 8250 console driver")
erroneous tries to read the FCR register content, but this register is
write-only.

This patch fixes that by reading the content from the port struct fcr
field.

Thanks to Jon Hunter and Jiri Slaby.

Suggested-by: Jiri Slaby <jirislaby@kernel.org>
Reported-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Wander Lairson Costa <wander@redhat.com>
---
 drivers/tty/serial/8250/8250_port.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 2abb3de11a48..9f3fa9fe2a4e 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -3410,7 +3410,7 @@ void serial8250_console_write(struct uart_8250_port *up, const char *s,
 
 	use_fifo = (up->capabilities & UART_CAP_FIFO) &&
 		port->fifosize > 1 &&
-		(serial_port_in(port, UART_FCR) & UART_FCR_ENABLE_FIFO) &&
+		(up->fcr & UART_FCR_ENABLE_FIFO) &&
 		/*
 		 * After we put a data in the fifo, the controller will send
 		 * it regardless of the CTS state. Therefore, only use fifo
-- 
2.35.1


  parent reply	other threads:[~2022-03-16 14:37 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-03-16 14:36 [PATCH v4 0/5] tty/8250: Use fifo in 8250 console driver Wander Lairson Costa
2022-03-16 14:36 ` [PATCH v4 1/5] serial/8250: " Wander Lairson Costa
2022-03-16 15:27   ` David Laight
2022-03-17 12:27     ` Wander Costa
2022-03-16 14:36 ` Wander Lairson Costa [this message]
2022-03-17  8:29   ` [PATCH v4 2/5] serial/8250: Use the cache value of the FCR register Ilpo Järvinen
2022-03-17 12:03     ` Wander Costa
2022-03-16 14:36 ` [PATCH v4 3/5] serial/8250: Use tx_loadsz as the transmitter fifo size Wander Lairson Costa
2022-03-16 14:36 ` [PATCH v4 4/5] serial/8250: exclude BCM283x from console_fifo_write Wander Lairson Costa
2022-03-16 14:36 ` [PATCH v4 5/5] serial/8250: Only use fifo after the port is initialized in console_write Wander Lairson Costa
2022-03-17  7:06   ` Jiri Slaby
2022-03-17 12:22     ` Wander Costa
2022-03-17  8:43   ` Ilpo Järvinen
2022-03-17 12:23     ` Wander Costa
2022-03-16 16:13 ` [PATCH v4 0/5] tty/8250: Use fifo in 8250 console driver Andy Shevchenko
2022-03-16 16:14   ` Andy Shevchenko
2022-03-16 16:37   ` Wander Costa
2022-03-17 15:47 ` Steven Rostedt

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