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

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Date:	Thu, 20 Jan 2011 17:18:56 +0530
From:	"G, Manjunath Kondaiah" <manjugk@...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

On Wed, Jan 19, 2011 at 07:28:20PM +0530, Govindraj wrote:
> 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.

With below patch, it works fine on TeraTerm. However, I am not able to
perform the same on minicom.

Tested-by: Manjunath G Kondaiah <manjugk@...com>

-Manjunath

> 
> 
> 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
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