From: Arnd Bergmann <arnd@arndb.de>
To: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@lists.codethink.co.uk,
linux-samsung-soc@vger.kernel.org, linux-pm@vger.kernel.org,
Viresh Kumar <viresh.kumar@linaro.org>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
Ben Dooks <ben.dooks@codethink.co.uk>
Subject: Re: [PATCH 1/2] cpufreq: exynos: use relaxed IO accesors
Date: Wed, 22 Jun 2016 11:53:32 +0200 [thread overview]
Message-ID: <3668897.kYSEflAvDO@wuerfel> (raw)
In-Reply-To: <1466587984-14105-1-git-send-email-ben.dooks@codethink.co.uk>
On Wednesday, June 22, 2016 10:33:03 AM CEST Ben Dooks wrote:
> The use of __raw IO accesors is not endian safe and should be used
> sparingly. The relaxed variants should be as lightweight and also
> are endian safe.
>
> Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
>
Why not use the normal readl/writel() here instead of the relaxed version?
Either one should work here, but in general I'd recommend using the
non-relaxed version unless code is particularly performance sensitive.
The main argument for that is to not let people get used to using
_relaxed() all the time because it causes some very hard to debug
problems in the cases where you actually need the barriers.
Arnd
WARNING: multiple messages have this Message-ID (diff)
From: arnd@arndb.de (Arnd Bergmann)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 1/2] cpufreq: exynos: use relaxed IO accesors
Date: Wed, 22 Jun 2016 11:53:32 +0200 [thread overview]
Message-ID: <3668897.kYSEflAvDO@wuerfel> (raw)
In-Reply-To: <1466587984-14105-1-git-send-email-ben.dooks@codethink.co.uk>
On Wednesday, June 22, 2016 10:33:03 AM CEST Ben Dooks wrote:
> The use of __raw IO accesors is not endian safe and should be used
> sparingly. The relaxed variants should be as lightweight and also
> are endian safe.
>
> Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
>
Why not use the normal readl/writel() here instead of the relaxed version?
Either one should work here, but in general I'd recommend using the
non-relaxed version unless code is particularly performance sensitive.
The main argument for that is to not let people get used to using
_relaxed() all the time because it causes some very hard to debug
problems in the cases where you actually need the barriers.
Arnd
next prev parent reply other threads:[~2016-06-22 9:53 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-22 9:33 [PATCH 1/2] cpufreq: exynos: use relaxed IO accesors Ben Dooks
2016-06-22 9:33 ` Ben Dooks
2016-06-22 9:35 ` Viresh Kumar
2016-06-22 9:35 ` Viresh Kumar
2016-06-22 9:37 ` Ben Dooks
2016-06-22 9:37 ` Ben Dooks
2016-06-22 9:53 ` Arnd Bergmann [this message]
2016-06-22 9:53 ` Arnd Bergmann
2016-06-22 10:36 ` Krzysztof Kozlowski
2016-06-22 10:36 ` Krzysztof Kozlowski
2016-06-22 10:37 ` Viresh Kumar
2016-06-22 10:37 ` Viresh Kumar
2016-06-22 11:59 ` Krzysztof Kozlowski
2016-06-22 11:59 ` Krzysztof Kozlowski
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