Bug#774896: Exynos4 CONFIG_HZ
2015-01-18 17:57 GMT+01:00 Sten Spans <sten@blinkenlights.nl>:
>
> With the improvements in upstream support for exynos4 devices
> I've been looking into adding support odroid devices to Debian's
> armmp kernel. The kernel config changes needed are quite minimal
> as can be seen here:
>
> https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=774896
>
> Mostly enabling support and various modules.
>
> However as Ian Campbell notes, enabling ARCH_EXYNOS4 triggers
> the following from arch/arm/Kconfig:
> config HZ_FIXED
> int
> default 200 if ARCH_EBSA110 || ARCH_S3C24XX || \
> ARCH_S5PV210 || ARCH_EXYNOS4
> default AT91_TIMER_HZ if ARCH_AT91
> default SHMOBILE_TIMER_HZ if ARCH_SHMOBILE_LEGACY
> default 0
>
> This forces CONFIG_HZ=200 for the entire armmp kernel, which is
> undesirable. The reason for this setting isn't very clear to either
> me or Ian. I personally have verified that HZ=250 (the default for debian
> armmp kernels) boots fine.
>
> Is there a particular reason for this setting?
> Would a patch removing this requirement for ARCH_EXYNOS4 be accepted?
+Cc Kukjin Kim
I cannot find a valid reason for fixed 200 Hz, especially that other
values (<100, 1000>) are working. Maybe Kukjin will share some light
on this?
Best regards,
Krzysztof
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