From: Joe Perches <joe@perches.com>
To: Guenter Roeck <linux@roeck-us.net>
Cc: linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org,
Zhang Rui <rui.zhang@intel.com>,
Eduardo Valentin <eduardo.valentin@ti.com>
Subject: Re: [PATCH] thermal: Fix KELVIN_TO_CELSIUS macro
Date: Sun, 23 Mar 2014 21:25:32 -0700 [thread overview]
Message-ID: <1395635132.13968.40.camel@joe-AO722> (raw)
In-Reply-To: <1395634496-25040-1-git-send-email-linux@roeck-us.net>
On Sun, 2014-03-23 at 21:14 -0700, Guenter Roeck wrote:
> It is always a good idea to use paranthesis around macro parameters
> to avoid undesired side effects.
>
> In this specific case, KELVIN_TO_CELSIUS() is used in
> drivers/platform/x86/asus-wmi.c with parameter "value & 0xFFFF",
> which due to operator evaluation order causes more or less random
> results.
Maybe it's better to use a statement expression to avoid
multiple calculations of t
Maybe;
#define KELVIN_TO_CELSIUS(t) \
({ \
long _t = (long)(t) - 2732; \
_t >= 0 ? (_t + 5) / 10 : (_t - 5) / 10; \
})
next prev parent reply other threads:[~2014-03-24 4:25 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-24 4:14 [PATCH] thermal: Fix KELVIN_TO_CELSIUS macro Guenter Roeck
2014-03-24 4:25 ` Joe Perches [this message]
2014-03-24 5:30 ` Guenter Roeck
2014-04-03 2:40 ` Zhang Rui
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