[PATCH] watchdog: kempld-wdt: Use the correct value when configuring the prescaler with the watchdog

[PATCH] watchdog: kempld-wdt: Use the correct value when configuring the prescaler with the watchdog

[gundberg]

Use the prescaler index, rather than its value, to configure the watchdog.
This will prevent a mismatch with the prescaler used to calculate the cycles.

Signed-off-by: Per Gundberg <per.gundberg@icomera.com>
---
 drivers/watchdog/kempld_wdt.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- src/drivers/watchdog/kempld_wdt.c.orig	2014-04-24 07:32:08.463745055 +0000
+++ src/drivers/watchdog/kempld_wdt.c	2014-04-24 07:34:09.839739808 +0000
@@ -163,7 +163,7 @@ static int kempld_wdt_set_stage_timeout(
 	kempld_get_mutex(pld);
 	stage_cfg = kempld_read8(pld, KEMPLD_WDT_STAGE_CFG(stage->id));
 	stage_cfg &= ~STAGE_CFG_PRESCALER_MASK;
-	stage_cfg |= STAGE_CFG_SET_PRESCALER(prescaler);
+	stage_cfg |= STAGE_CFG_SET_PRESCALER(PRESCALER_21);
 	kempld_write8(pld, KEMPLD_WDT_STAGE_CFG(stage->id), stage_cfg);
 	kempld_write32(pld, KEMPLD_WDT_STAGE_TIMEOUT(stage->id),
 			stage_timeout);

Re: [PATCH] watchdog: kempld-wdt: Use the correct value when configuring the prescaler with the watchdog

[Guenter Roeck]

On Thu, Apr 24, 2014 at 03:49:19PM +0200, gundberg wrote:
> Use the prescaler index, rather than its value, to configure the watchdog.
> This will prevent a mismatch with the prescaler used to calculate the cycles.
> 
> Signed-off-by: Per Gundberg <per.gundberg@icomera.com>

Good catch. Looks correct to me. Michael, any comments ?

Reviewed-by: Guenter Roeck <linux@roeck-us.net>

> ---
>  drivers/watchdog/kempld_wdt.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> --- src/drivers/watchdog/kempld_wdt.c.orig	2014-04-24 07:32:08.463745055 +0000
> +++ src/drivers/watchdog/kempld_wdt.c	2014-04-24 07:34:09.839739808 +0000
> @@ -163,7 +163,7 @@ static int kempld_wdt_set_stage_timeout(
>  	kempld_get_mutex(pld);
>  	stage_cfg = kempld_read8(pld, KEMPLD_WDT_STAGE_CFG(stage->id));
>  	stage_cfg &= ~STAGE_CFG_PRESCALER_MASK;
> -	stage_cfg |= STAGE_CFG_SET_PRESCALER(prescaler);
> +	stage_cfg |= STAGE_CFG_SET_PRESCALER(PRESCALER_21);
>  	kempld_write8(pld, KEMPLD_WDT_STAGE_CFG(stage->id), stage_cfg);
>  	kempld_write32(pld, KEMPLD_WDT_STAGE_TIMEOUT(stage->id),
>  			stage_timeout);
> --
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Re: [PATCH] watchdog: kempld-wdt: Use the correct value when configuring the prescaler with the watchdog

[Michael Brunner]

On Thu, 24 Apr 2014 08:15:40 -0700, Guenter Roeck <linux@roeck-us.net>
wrote:
> On Thu, Apr 24, 2014 at 03:49:19PM +0200, gundberg wrote:
> > Use the prescaler index, rather than its value, to configure the
> > watchdog. This will prevent a mismatch with the prescaler used to
> > calculate the cycles.
> > 
> > Signed-off-by: Per Gundberg <per.gundberg@icomera.com>
> 
> Good catch. Looks correct to me. Michael, any comments ?
> 
> Reviewed-by: Guenter Roeck <linux@roeck-us.net>

Setting the prescaler incorrectly this way can cause the system to
reboot nearly immediately when activating the watchdog - not good.
This should also be applied to the stable revisions as this code is
included since 3.11.

Reviewed-by: Michael Brunner <michael.brunner@kontron.com>
Tested-by: Michael Brunner <michael.brunner@kontron.com>

Thanks,
Michael

Re: [PATCH] watchdog: kempld-wdt: Use the correct value when configuring the prescaler with the watchdog

[Wim Van Sebroeck]

Hi Per,

> Use the prescaler index, rather than its value, to configure the watchdog.
> This will prevent a mismatch with the prescaler used to calculate the
> cycles.
> 
> Signed-off-by: Per Gundberg <per.gundberg@icomera.com>
> ---
>  drivers/watchdog/kempld_wdt.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> --- src/drivers/watchdog/kempld_wdt.c.orig    2014-04-24 07:32:08.463745055
> +0000
> +++ src/drivers/watchdog/kempld_wdt.c    2014-04-24 07:34:09.839739808 +0000
> @@ -163,7 +163,7 @@ static int kempld_wdt_set_stage_timeout(
>      kempld_get_mutex(pld);
>      stage_cfg = kempld_read8(pld, KEMPLD_WDT_STAGE_CFG(stage->id));
>      stage_cfg &= ~STAGE_CFG_PRESCALER_MASK;
> -    stage_cfg |= STAGE_CFG_SET_PRESCALER(prescaler);
> +    stage_cfg |= STAGE_CFG_SET_PRESCALER(PRESCALER_21);
>      kempld_write8(pld, KEMPLD_WDT_STAGE_CFG(stage->id), stage_cfg);
>      kempld_write32(pld, KEMPLD_WDT_STAGE_TIMEOUT(stage->id),
>              stage_timeout);

This patch has been added to linux-watchdog-next.

Kind regards,
Wim.