linux-kernel - Re: [PATCH] serial: revert "Use block_til

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Date:	Mon, 21 Jun 2010 22:57:03 +0200
From:	Arnd Bergmann <arnd@...db.de>
To:	Alan Cox <alan@...rguk.ukuu.org.uk>
Cc:	Tony Luck <tony.luck@...el.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	linux-kernel@...r.kernel.org, Greg KH <gregkh@...e.de>,
	Thomas Gleixner <tglx@...utronix.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	John Kacur <jkacur@...hat.com>,
	Al Viro <viro@...iv.linux.org.uk>, Ingo Molnar <mingo@...e.hu>
Subject: Re: [PATCH] serial: revert "Use block_til_ready helper"

On Monday 21 June 2010 16:13:09 Alan Cox wrote:

> and paste it into
> 
> void tty_port_raise_dtr_rts(struct tty_port *port)
> {
>         if (port->ops->dtr_rts)
>                 port->ops->dtr_rts(port, 1);
> 
> 		-->> HERE <<--
> }
> 
> 
> (the mutex is held by the caller)
> 
> That 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.

I had to do it slightly different, see below. This patch also fixes
the garbled output and lets me run cat> and getty on the onboard 16550a,
but unlike the previous patch, I can't get a minicom connection between
the two ports using hardware flow control now, so it seems that there
is still another problem.

Signed-off-by: Arnd Bergmann <arnd@...db.de>

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;
 }
--
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