Guenter, On Mon, Nov 25, 2013 at 3:23 PM, Guenter Roeck <linux@xxxxxxxxxxxx> wrote: > On 11/25/2013 02:55 PM, Doug Anderson wrote: >> >> 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 >> CPU_FREQ_S3C24XX 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 CPU_FREQ_S3C24XX 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> >> --- >> drivers/watchdog/s3c2410_wdt.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/watchdog/s3c2410_wdt.c >> b/drivers/watchdog/s3c2410_wdt.c >> index 7d8fd04..4980f84 100644 >> --- a/drivers/watchdog/s3c2410_wdt.c >> +++ b/drivers/watchdog/s3c2410_wdt.c >> @@ -264,7 +264,7 @@ static irqreturn_t s3c2410wdt_irq(int irqno, void >> *param) >> return IRQ_HANDLED; >> } >> >> -#ifdef CONFIG_CPU_FREQ >> +#ifdef CONFIG_CPU_FREQ_S3C24XX >> > Where is the CPU_FREQ_S3C24XX configuration option defined ? I don't see it > in the current upstream kernel, so it appears that this depends on some > out-of-tree changes. Whoops! I guess I just trusted another patch and didn't dig. I was basing this on https://patchwork.kernel.org/patch/3023421/ Ah, I see that Tomasz just found the answer. I'll update my patch. -Doug -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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