linux-kernel - [PATCH] serial: fix termios settings in open

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Date:	Tue, 29 Jun 2010 22:31:40 +0200
From:	Arnd Bergmann <arnd@...db.de>
To:	Greg Kroah-Hartman <gregkh@...e.de>
Cc:	linux-kernel@...r.kernel.org, Arnd Bergmann <arnd@...db.de>,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	Tony Luck <tony.luck@...el.com>
Subject: [PATCH] serial: fix termios settings in open

Move termios initialization in open into uart_dtr_rts to make sure
it always gets called when necessary. Based on a suggestion from
Alan Cox.

Alan writes:
Ok this sort of makes sense. Something isn't getting initialised and both
getty and minicom will do a termios set which is sorting it out.
This is occurring because the generic block_til_ready sets
ASYNCB_NORMAL_ACTIVE so the termios updating gets skipped.

This patch should cure it and then we can think about doing it more
elegantly by getting the serial layer to use tty_port_open, kfifo and
the like and removing the tons of repeated crap in all the drivers.

Signed-off-by: Arnd Bergmann <arnd@...db.de>
Reported-by: Tony Luck <tony.luck@...el.com>
Cc: Alan Cox <alan@...rguk.ukuu.org.uk>
Cc: Tony Luck <tony.luck@...el.com>
---

Greg, please apply to you tty series. I thought there was a bug
in this patch but it turns out that this was incorrect. There
is still something fishy on my system with hardware flow control,
but it seems to be a preexisting condition, so this patch is actually
good, unlike what I said before. Please apply next to "serial: Use
block_til_ready helper", which introduces the ploblem.

 drivers/serial/serial_core.c |   19 +++++++++----------
 1 files changed, 9 insertions(+), 10 deletions(-)

diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
index 78b1eac..cd85112 100644
--- a/drivers/serial/serial_core.c
+++ b/drivers/serial/serial_core.c
@@ -1533,8 +1533,16 @@ static void uart_dtr_rts(struct tty_port *port, int onoff)
 	struct uart_state *state = container_of(port, struct uart_state, port);
 	struct uart_port *uport = state->uart_port;

-	if (onoff)
+	if (onoff) {
 		uart_set_mctrl(uport, TIOCM_DTR | TIOCM_RTS);
+
+		/*
+		 * If this is the first open to succeed,
+		 * adjust things to suit.
+		 */
+		if (!test_and_set_bit(ASYNCB_NORMAL_ACTIVE, &port->flags))
+			uart_update_termios(port->tty, state);
+	}
 	else
 		uart_clear_mctrl(uport, TIOCM_DTR | TIOCM_RTS);
 }
@@ -1649,15 +1657,6 @@ static int uart_open(struct tty_struct *tty, struct file *filp)
 	if (retval == 0)
 		retval = tty_port_block_til_ready(port, tty, filp);

-	/*
-	 * If this is the first open to succeed, adjust things to suit.
-	 */
-	if (retval == 0 && !(port->flags & ASYNC_NORMAL_ACTIVE)) {
-		set_bit(ASYNCB_NORMAL_ACTIVE, &port->flags);
-
-		uart_update_termios(tty, state);
-	}
-
 fail:
 	return retval;
 }
-- 
1.7.1

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