linux-kernel - Re: [PATCHv2] OMAP: Enable Magic SysRq on serial console ttyOx

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Date:	Thu, 20 Jan 2011 07:58:06 +0100
From:	Thomas Weber <thomas.weber.linux@...glemail.com>
To:	Govindraj <govindraj.ti@...il.com>
CC:	Thomas Weber <weber@...science.de>,
	"G, Manjunath Kondaiah" <manjugk@...com>,
	linux-omap@...r.kernel.org, Tony Lindgren <tony@...mide.com>,
	"Govindraj.R" <govindraj.raja@...com>,
	Greg Kroah-Hartman <gregkh@...e.de>,
	Andrei Emeltchenko <andrei.emeltchenko@...ia.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCHv2] OMAP: Enable Magic SysRq on serial console ttyOx

Am 19.01.2011 14:58, schrieb Govindraj:
> On Wed, Jan 19, 2011 at 7:01 PM, Thomas Weber <weber@...science.de> wrote:
>> Am 19.01.2011 14:00, schrieb G, Manjunath Kondaiah:
>>> On Wed, Jan 19, 2011 at 03:01:39PM +0530, Govindraj wrote:
>>>> On Wed, Jan 19, 2011 at 2:11 PM, Thomas Weber <weber@...science.de> wrote:
>>>>> Magic SysRq key is not working for OMAP on new serial
>>>>> console ttyOx because SUPPORT_SYSRQ is not defined
>>>>> for omap-serial.
>>>>>
>>>>> This patch defines SUPPORT_SYSRQ in omap-serial and
>>>>> enables handling of Magic SysRq character.
>>>>>
>>>>> Signed-off-by: Thomas Weber <weber@...science.de>
>>>>
>>>> Looks fine to me.
>>>>
>>>> Acked-by: Govindraj.R <govindraj.raja@...com>
>>> I tried to use SysRq key on minicom after applying this patch, it looks
>>> like it is not triggering sysrq event.
>>>
>>> Am I missing anything?
>>>
>>> -Manjunath
>>> --
>> Hello Manjunath,
>>
>> Do you have CONFIG_MAGIC_SYSRQ enabled?
>> Magic SysRq key in Kernel Hacking
>>
>> I tested it on Devkit8000 (beagle board clone).
>>
> 
> re-setting lsr_break_flag to 0 in receive chars is causing issues
> in getting sysrq key break sequence on omap-serial.c
> 
> Manju,
> 
> can you try this change on your environment.
> With below change works for me on 3430SDP/4430SDP.
> key sequence I checked.
> [alt + b + t]  => shows trace of tasks running.
> [alt + b + b] => system reboot.
> 
> 
> diff --git a/drivers/serial/omap-serial.c b/drivers/serial/omap-serial.c
> index 1201eff..6df623e 100644
> --- a/drivers/serial/omap-serial.c
> +++ b/drivers/serial/omap-serial.c
> @@ -20,6 +20,10 @@
>   * this driver as required for the omap-platform.
>   */
> 
> +#if defined(CONFIG_SERIAL_OMAP_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
> +#define SUPPORT_SYSRQ
> +#endif
> +
>  #include <linux/module.h>
>  #include <linux/init.h>
>  #include <linux/console.h>
> @@ -190,7 +194,6 @@ static inline void receive_chars(struct
> uart_omap_port *up, int *status)
>                         if (up->port.line == up->port.cons->index) {
>                                 /* Recover the break flag from console xmit */
>                                 lsr |= up->lsr_break_flag;
> -                               up->lsr_break_flag = 0;
>                         }
>  #endif
>                         if (lsr & UART_LSR_BI)
> 
> 
> --
> Thanks,
> Govindraj.R
> --

Hello,

both version works for me.

Thomas

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