Bug#774896: Exynos4 CONFIG_HZ

From	Salvatore Bonaccorso <carnil@debian.org>
Newsgroups	linux.debian.bugs.dist, linux.debian.kernel
Subject	Bug#774896: Exynos4 CONFIG_HZ
Date	2021-04-30 14:30 +0200
Message-ID	<C9Arn-7rb-3@gated-at.bofh.it> (permalink)
References	<oK1wl-hM-9@gated-at.bofh.it> <oKhKN-7Fo-5@gated-at.bofh.it> <oGqCZ-1p6-1@gated-at.bofh.it> <oKhKN-7Fo-5@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Cross-posted to 2 groups.

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Hi,

On Mon, Jan 19, 2015 at 11:23:04AM +0100, Krzysztof Kozłowski wrote:
> 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?

I'm not sure if this bugreport is still relevant, but in any case
upstream changed this in da6b21e97e39 ("ARM: Drop fixed 200 Hz timer
requirement from Samsung platforms").

In case the bugreport is not anymore relevant, let's close it.

Regards,
Salvatore

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Bug#774896: Exynos4 CONFIG_HZ Salvatore Bonaccorso <carnil@debian.org> - 2021-04-30 14:30 +0200

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