linux-kernel - Re: [PATCH 9/9 -v2] imx: serial: use tty_encode_baud

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Date:	Tue, 16 Jun 2009 09:28:01 +0200
From:	Sascha Hauer <s.hauer@...gutronix.de>
To:	Oskar Schirmer <os@...ix.com>
Cc:	Sascha Hauer <kernel@...gutronix.de>, linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Alan Cox <alan@...rguk.ukuu.org.uk>
Subject: Re: [PATCH 9/9 -v2] imx: serial: use tty_encode_baud_rate to set
	true rate

Hi,

On Wed, Jun 10, 2009 at 02:08:36PM +0200, Oskar Schirmer wrote:
> real baud rate may be different from the one requested.
> for upper layers, set the nearest value to the real rate
> in favour of the rate previously requested.
> 
> Signed-off-by: Oskar Schirmer <os@...ix.com>
> ---
>  drivers/serial/imx.c |    7 +++++++
>  1 files changed, 7 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/serial/imx.c b/drivers/serial/imx.c
> index 1c00e2a..c367160 100644
> --- a/drivers/serial/imx.c
> +++ b/drivers/serial/imx.c
> @@ -818,6 +818,7 @@ imx_set_termios(struct uart_port *port, struct ktermios *termios,
>  	unsigned int old_csize = old ? old->c_cflag & CSIZE : CS8;
>  	unsigned int div, ufcr;
>  	unsigned long num, denom;
> +	uint64_t tdiv64;
>  
>  	/*
>  	 * If we don't support modem control lines, don't allow
> @@ -930,6 +931,12 @@ imx_set_termios(struct uart_port *port, struct ktermios *termios,
>  	rational_best_approximation(16 * div * baud, sport->port.uartclk,
>  		1 << 16, 1 << 16, &num, &denom);
>  
> +	tdiv64 = sport->port.uartclk;
> +	tdiv64 *= num;
> +	do_div(tdiv64, denom * 16 * div);
> +	tty_encode_baud_rate(sport->port.info->port.tty,
> +		(speed_t)tdiv64, (speed_t)tdiv64);
> +
>  	num -= 1;
>  	denom -= 1;
>  

This patch breaks booting with a serial console on i.MX UARTs. The
following patch fixes this. Alan, please consider applying it.

Sascha


>From 4ac2e4dbb3bd31d67a395740b1d4f8206441141b Mon Sep 17 00:00:00 2001
From: Sascha Hauer <s.hauer@...gutronix.de>
Date: Tue, 16 Jun 2009 09:24:57 +0200
Subject: [PATCH] i.MX serial driver: Check for NULL pointer deref before calling  tty_encode_baud_rate

Signed-off-by: Sascha Hauer <s.hauer@...gutronix.de>
---
 drivers/serial/imx.c |   12 +++++++-----
 1 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/serial/imx.c b/drivers/serial/imx.c
index 285b414..5d7b58f 100644
--- a/drivers/serial/imx.c
+++ b/drivers/serial/imx.c
@@ -924,11 +924,13 @@ imx_set_termios(struct uart_port *port, struct ktermios *termios,
 	rational_best_approximation(16 * div * baud, sport->port.uartclk,
 		1 << 16, 1 << 16, &num, &denom);
 
-	tdiv64 = sport->port.uartclk;
-	tdiv64 *= num;
-	do_div(tdiv64, denom * 16 * div);
-	tty_encode_baud_rate(sport->port.info->port.tty,
-		(speed_t)tdiv64, (speed_t)tdiv64);
+	if (port->info && port->info->port.tty) {
+		tdiv64 = sport->port.uartclk;
+		tdiv64 *= num;
+		do_div(tdiv64, denom * 16 * div);
+		tty_encode_baud_rate(sport->port.info->port.tty,
+				(speed_t)tdiv64, (speed_t)tdiv64);
+	}
 
 	num -= 1;
 	denom -= 1;
-- 
1.6.3.1


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