Re: [PATCH v2] watchdog: s3c2410_wdt: Only register for cpufreq on ARM_S3C24XX_CPUFREQ

[Wim Van Sebroeck]

Hi Doug,

> On modern SoCs the watchdog timer is parented on a clock that doesn't
> change every time we have a cpufreq change.  That means we don't need
> to constantly adjust the watchdog timer, so avoid registering for and
> dealing with cpufreq transitions unless we've actually got
> CONFIG_ARM_S3C24XX_CPUFREQ defined.
> 
> Note that this is more than just an optimization.  The s3c2410
> watchdog driver actually pats the watchdog on every CPU frequency
> change.  On modern systems these happen many times per second (even in
> a system where "nothing" is happening).  That effectively makes any
> userspace watchdog program useless (the watchdog is constantly patted
> by the kernel).  If we need ARM_S3C24XX_CPUFREQ defined on a
> multiplatform kernel we'll need to make sure that kernel supports
> common clock and change this to user common clock framework.
> 
> Signed-off-by: Doug Anderson <dianders@xxxxxxxxxxxx>
> ---
> Changes in v2:
> - Use the updated config name.

Patch added to linux-watchdog-next.

Kind regards,
Wim.

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