From: Arnd Bergmann <arnd@arndb.de>
To: linux-arm-kernel@lists.infradead.org
Cc: amit daniel kachhap <amit.daniel@samsung.com>,
Daniel Lezcano <daniel.lezcano@linaro.org>,
Kukjin Kim <kgene.kim@samsung.com>,
David Riley <davidriley@chromium.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Doug Anderson <dianders@chromium.org>,
"linux-samsung-soc@vger.kernel.org"
<linux-samsung-soc@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Tomasz Figa <tomasz.figa@gmail.com>
Subject: Re: [PATCH v2] clocksource: exynos-mct: Register the timer for stable udelay
Date: Thu, 19 Jun 2014 12:29:55 +0200 [thread overview]
Message-ID: <4808230.DmzmRfAocp@wuerfel> (raw)
In-Reply-To: <CADGdYn6YObHdRq6A9-L7qbD+EYiPrwhrKkLwyA5Z=0tDoWUzvA@mail.gmail.com>
On Thursday 19 June 2014 15:51:58 amit daniel kachhap wrote:
> I also didn't want to use macros but used as a last option. you want
> me to put more comments here?
> Or something like below is also possible for checking the size of
> (unsigned long) in runtime.
>
> unsigned long x;
> unsigned int size = (char *)(&x + 1) - (char *)(&x);
reimplementing "sizeof (long)"?
> if (size == 4)
> return __raw_readl(reg_base + EXYNOS4_MCT_G_CNT_L);
readl_relaxed(), certainly
> else
> return exynos4_frc_read(&mct_frc);
>
> But this involves extra computation which should not be used for time
> critical functions.
sizeof is a constant expression, the compiler will optimize this.
Arnd
next prev parent reply other threads:[~2014-06-19 10:30 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-19 8:39 [PATCH v2] clocksource: exynos-mct: Register the timer for stable udelay Amit Daniel Kachhap
2014-06-19 9:11 ` Daniel Lezcano
2014-06-19 10:21 ` amit daniel kachhap
2014-06-19 10:29 ` Arnd Bergmann [this message]
2014-06-19 10:30 ` Daniel Lezcano
2014-06-19 11:00 ` amit daniel kachhap
2014-06-19 10:21 ` Tomasz Figa
2014-06-19 16:01 ` Doug Anderson
2014-06-19 16:17 ` Tomasz Figa
2014-06-19 16:31 ` Doug Anderson
2014-06-19 16:40 ` Tomasz Figa
2014-06-20 8:15 ` Will Deacon
2014-06-20 11:19 ` amit daniel kachhap
2014-06-20 17:47 ` Doug Anderson
2014-06-21 9:53 ` amit daniel kachhap
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