linux-kernel - [PATCH v2 1/3] serial: core: Store fifo timeout again

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Message-ID: <20240416182741.22514-2-mcpratt@pm.me>
Date: Tue, 16 Apr 2024 18:29:28 +0000
From: Michael Pratt <mcpratt@...me>
To: linux-kernel@...r.kernel.org, linux-serial@...r.kernel.org, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Jiri Slaby <jirislaby@...nel.org>
Cc: Wander Lairson Costa <wander@...hat.com>, Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>, Andy Shevchenko <andriy.shevchenko@...ux.intel.com>, Vamshi Gajjela <vamshigajjela@...gle.com>, Michael Pratt <mcpratt@...me>
Subject: [PATCH v2 1/3] serial: core: Store fifo timeout again

This is a partial revert of Commit f9008285bb69
("serial: Drop timeout from uart_port").

In order to prevent having to calculate a timeout
for the fifo device during a write operation, if enabled,
calculate it ahead of time and store the value of the timeout
in a struct member of uart_port.

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

 drivers/tty/serial/serial_core.c | 3 +++
 include/linux/serial_core.h      | 1 +
 2 files changed, 4 insertions(+)

diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index ff85ebd3a007..9b3176d684a4 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -414,6 +414,9 @@ uart_update_timeout(struct uart_port *port, unsigned int cflag,
 
 	temp *= NSEC_PER_SEC;
 	port->frame_time = (unsigned int)DIV64_U64_ROUND_UP(temp, baud);
+
+	if (port->fifosize > 1)
+		port->timeout = uart_fifo_timeout(port);
 }
 EXPORT_SYMBOL(uart_update_timeout);
 
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index 0a0f6e21d40e..c6422021152f 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -561,6 +561,7 @@ struct uart_port {
 
 	bool			hw_stopped;		/* sw-assisted CTS flow state */
 	unsigned int		mctrl;			/* current modem ctrl settings */
+	unsigned long		timeout;		/* character-based timeout */
 	unsigned int		frame_time;		/* frame timing in ns */
 	unsigned int		type;			/* port type */
 	const struct uart_ops	*ops;
-- 
2.30.2