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Date: Tue, 16 Apr 2024 18:29:56 +0000
To: linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Jiri Slaby <jirislaby@kernel.org>
From: Michael Pratt <mcpratt@pm.me>
Cc: Wander Lairson Costa <wander@redhat.com>, =?utf-8?Q?Ilpo_J=C3=A4rvinen?= <ilpo.jarvinen@linux.intel.com>, Andy Shevchenko <andriy.shevchenko@linux.intel.com>, Vamshi Gajjela <vamshigajjela@google.com>, Michael Pratt <mcpratt@pm.me>
Subject: [PATCH v2 2/3] serial: 8250: Store whether fifo device is enabled
Message-ID: <20240416182741.22514-3-mcpratt@pm.me>
In-Reply-To: <20240416182741.22514-1-mcpratt@pm.me>
References: <20240416182741.22514-1-mcpratt@pm.me>
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Currently, there are 7 checks for whether to enable
the internal fifo device of a 8250/16550 type uart.

Instead of checking all 7 values again whenever
we need to know whether we have the fifo device enabled,
store the result as a struct member of uart_8250_port.

This can, for example, lessen the amount
of calculations done during a write operation.

Signed-off-by: Michael Pratt <mcpratt@pm.me>
---
V1 -> V2: new commit

 drivers/tty/serial/8250/8250_port.c | 2 ++
 include/linux/serial_8250.h         | 1 +
 2 files changed, 3 insertions(+)

diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/=
8250_port.c
index fc9dd5d45295..5b0cfe6bc98c 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -3392,6 +3392,8 @@ void serial8250_console_write(struct uart_8250_port *=
up, const char *s,
 =09=09 */
 =09=09!(up->port.flags & UPF_CONS_FLOW);
=20
+=09up->fifo_enable =3D use_fifo;
+
 =09if (likely(use_fifo))
 =09=09serial8250_console_fifo_write(up, s, count);
 =09else
diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h
index fd59ed2cca53..017429f0e743 100644
--- a/include/linux/serial_8250.h
+++ b/include/linux/serial_8250.h
@@ -127,6 +127,7 @@ struct uart_8250_port {
 =09struct list_head=09list;=09=09/* ports on this IRQ */
 =09u32=09=09=09capabilities;=09/* port capabilities */
 =09u16=09=09=09bugs;=09=09/* port bugs */
+=09unsigned int=09=09fifo_enable;=09/* fifo enabled if capable */
 =09unsigned int=09=09tx_loadsz;=09/* transmit fifo load size */
 =09unsigned char=09=09acr;
 =09unsigned char=09=09fcr;
--=20
2.30.2