linux-kernel - console resume broken since ba15ab0e8de0d4439a91342ad52d55ca9e313f3d

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Message-ID: <20090930151103.GU27039@pengutronix.de>
Date:	Wed, 30 Sep 2009 17:11:03 +0200
From:	Sascha Hauer <s.hauer@...gutronix.de>
To:	linux-kernel@...r.kernel.org
Cc:	Deepak Saxena <dsaxena@...top.org>,
	Greg Kroah-Hartman <gregkh@...e.de>
Subject: console resume broken since
	ba15ab0e8de0d4439a91342ad52d55ca9e313f3d


This patch fixes setting the console speed if console suspend is disabled
by breaking it if it is enabled, see below:

> commit ba15ab0e8de0d4439a91342ad52d55ca9e313f3d
> Author: Deepak Saxena <dsaxena@...top.org>
> Date:   Sat Sep 19 13:13:33 2009 -0700
> 
>     Set proper console speed on resume if console suspend is disabled
>     
>     Commit b5b82df6, from May 2007, breaks no_console_suspend on the OLPC
>     XO laptop. Basically what happens is that upon returning from resume,
>     serial8250_resume_port() will reconfigure the port for high speed
>     mode and all console output will be garbled, making debug of the
>     resume path painful. This patch modifies uart_resume_port() to
>     reset the port to the state it was in before we suspended.
>     
>     Original patch by Marcelo Tosatti
>     
>     Second patch by Deepak then reworked by Alan to fit with the tty changes
>     before it got submitted. Also fixed the console path to set c_i/ospeed as
>     some drivers require the termios fields are valid
>     
>     Signed-off-by: Deepak Saxena <dsaxena@...top.org>
>     Signed-off-by: Alan Cox <alan@...ux.intel.com>
>     Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>
> 
> diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
> index 3fd0134..2514d00 100644
> --- a/drivers/serial/serial_core.c
> +++ b/drivers/serial/serial_core.c
> @@ -2068,11 +2068,29 @@ int uart_resume_port(struct uart_driver *drv, struct uart_port *uport)
>  	struct tty_port *port = &state->port;
>  	struct device *tty_dev;
>  	struct uart_match match = {uport, drv};
> +	struct ktermios termios;
>  
>  	mutex_lock(&port->mutex);
>  
>  	if (!console_suspend_enabled && uart_console(uport)) {
>  		/* no need to resume serial console, it wasn't suspended */
> +		/*
> +		 * First try to use the console cflag setting.
> +		 */
> +		memset(&termios, 0, sizeof(struct ktermios));
> +		termios.c_cflag = uport->cons->cflag;
> +		/*
> +		 * If that's unset, use the tty termios setting.
> +		 */
> +		if (termios.c_cflag == 0)
> +			termios = *state->port.tty->termios;
> +		else {
> +			termios.c_ispeed = termios.c_ospeed =
> +				tty_termios_input_baud_rate(&termios);
> +			termios.c_ispeed = termios.c_ospeed =
> +				tty_termios_baud_rate(&termios);
> +		}
> +		uport->ops->set_termios(uport, &termios, NULL);
>  		mutex_unlock(&port->mutex);
>  		return 0;
>  	}
> @@ -2089,20 +2107,6 @@ int uart_resume_port(struct uart_driver *drv, struct uart_port *uport)
>  	 * Re-enable the console device after suspending.
>  	 */
>  	if (uart_console(uport)) {
> -		struct ktermios termios;
> -
> -		/*
> -		 * First try to use the console cflag setting.
> -		 */
> -		memset(&termios, 0, sizeof(struct ktermios));
> -		termios.c_cflag = uport->cons->cflag;
> -
> -		/*
> -		 * If that's unset, use the tty termios setting.
> -		 */
> -		if (port->tty && termios.c_cflag == 0)
> -			termios = *port->tty->termios;
> -
>  		uart_change_pm(state, 0);
>  		uport->ops->set_termios(uport, &termios, NULL);


We call ->set_termios with an unitialized struct ktermios here.

Any ideas what to do?

Sascha

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