linux-kernel - Re: [PATCH v2] thermal: consistently use int for temperatures

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Date:	Thu, 23 Jul 2015 14:07:59 +0200
From:	Pavel Machek <pavel@....cz>
To:	Sascha Hauer <s.hauer@...gutronix.de>
Cc:	linux-pm@...r.kernel.org, Zhang Rui <rui.zhang@...el.com>,
	Eduardo Valentin <edubezval@...il.com>,
	linux-kernel@...r.kernel.org,
	Punit Agrawal <punit.agrawal@....com>,
	Jean Delvare <jdelvare@...e.de>,
	Peter Feuerer <peter@...e.net>,
	Heiko Stuebner <heiko@...ech.de>,
	Lukasz Majewski <l.majewski@...sung.com>,
	Stephen Warren <swarren@...dotorg.org>,
	Thierry Reding <thierry.reding@...il.com>,
	linux-acpi@...r.kernel.org, platform-driver-x86@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-omap@...r.kernel.org,
	linux-samsung-soc@...r.kernel.org,
	Guenter Roeck <linux@...ck-us.net>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Maxime Ripard <maxime.ripard@...e-electrons.com>,
	Darren Hart <dvhart@...radead.org>, lm-sensors@...sensors.org
Subject: Re: [PATCH v2] thermal: consistently use int for temperatures

On Tue 2015-07-21 09:21:32, Sascha Hauer wrote:
> The thermal code uses int, long and unsigned long for temperatures
> in different places.
> 
> Using an unsigned type limits the thermal framework to positive
> temperatures without need. Also several drivers currently will report
> temperatures near UINT_MAX for temperatures below 0°C. This will probably
> immediately shut the machine down due to overtemperature if started below
> 0°C.
> 
> 'long' is 64bit on several architectures. This is not needed since INT_MAX °mC
> is above the melting point of all known materials.

Can we do something like

typedef millicelsius_t int;

...to document the units?

> Consistently use a plain 'int' for temperatures throughout the thermal code and
> the drivers. This only changes the places in the drivers where the temperature
> is passed around as pointer, when drivers internally use another type this is
> not changed.

									Pavel

-- 
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