Messages in this thread | | | Subject | Re: [RFC PATCH] watchdog: s3c2410_wdt: Add max and min timeout values | From | Guenter Roeck <> | Date | Thu, 3 Mar 2016 21:32:03 -0800 |
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On 03/03/2016 04:26 AM, Krzysztof Kozlowski wrote: > 2016-03-03 20:55 GMT+09:00 Javier Martinez Canillas <javier@osg.samsung.com>: >> Hello Guenter, >> >> >> On 03/03/2016 01:50 AM, Guenter Roeck wrote: >>> A watchdog driver using a non-static clock must register a clock change >>> notifier >>> to handle the clock rate change and update its settings accordingly. >>> >>> I would also argue that the maximum timeout should be set to the minimum >>> possible value (probably associated with the highest possible frequency). >>> All other cases might end up causing trouble if a clock frequency >>> chance results in an enforced timeout change, since there is currently >>> no mechanism to inform user space about such a change. >>> >>> Example: maximum possible timeout changes from 1 minute to 30 seconds. >>> The timeout was set to 1 minute, and has to be reduced to 30 seconds. >>> Very likely result is that the watchdog will reset the system because >>> user space still believes that the timeout is 60 seconds and doesn't >>> ping the watchdog often enough to prevent it. >>> >> >> Agreed. >> >> In any case this discussion is not related to this patch since currently >> in mainline the watchdog source clock is fixed and does not change. >> >> So, $SUBJECT solves the issue of not having the fixed .{min,max}_timeout >> defined to allow the watchdog_timeout_invalid() function to check values >> set by WDIOC_SETTIMEOUT and avoid calling the .set_timeout callback. >> >> If later someone tries to scale a parent clock used by many drivers, then >> the submitter should make sure that no regressions are added by the patch. > > Sounds good. For this patch then: > Reviewed-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Agreed.
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Thanks, Guenter
> > Best regards, > Krzysztof > -- > To unsubscribe from this list: send the line "unsubscribe linux-watchdog" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >
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