From: Akinobu Mita <akinobu.mita@gmail.com>
To: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: linux-hwmon@vger.kernel.org,
Amit Kucheria <amit.kucheria@verdurent.com>,
Jean Delvare <jdelvare@suse.com>,
Sagi Grimberg <sagi@grimberg.me>,
Linux PM <linux-pm@vger.kernel.org>,
Sujith Thomas <sujith.thomas@intel.com>,
LKML <linux-kernel@vger.kernel.org>,
Linux NVMe Mailinglist <linux-nvme@lists.infradead.org>,
Jens Axboe <axboe@fb.com>, Guenter Roeck <linux@roeck-us.net>,
Keith Busch <kbusch@kernel.org>,
Darren Hart <dvhart@infradead.org>,
Zhang Rui <rui.zhang@intel.com>, Christoph Hellwig <hch@lst.de>,
Andy Shevchenko <andy@infradead.org>
Subject: Re: [PATCH v2 1/8] add header file for kelvin to/from Celsius conversion helpers
Date: Sun, 8 Dec 2019 00:57:28 +0900 [thread overview]
Message-ID: <CAC5umyg3J98ntrezxskdKTgdP-WsL9VjtzHpXxyxGxTZxcaQ8A@mail.gmail.com> (raw)
In-Reply-To: <5f85f65c-78b6-0b63-f975-a216f9823985@linaro.org>
2019年12月7日(土) 1:49 Daniel Lezcano <daniel.lezcano@linaro.org>:
>
> On 28/11/2019 15:54, Akinobu Mita wrote:
> > There are several helper macros to convert kelvin to/from Celsius in
> > <linux/thermal.h> for thermal drivers. These are useful for any other
> > drivers or subsystems, but it's odd to include <linux/thermal.h> just for
> > the helpers.
> >
> > This adds a new <linux/temperature.h> that provides the equivalent inline
> > functions for any drivers or subsystems. It is intended to replace the
> > helpers in <linux/thermal.h>.
> >
> > Cc: Sujith Thomas <sujith.thomas@intel.com>
> > Cc: Darren Hart <dvhart@infradead.org>
> > Cc: Andy Shevchenko <andy@infradead.org>
> > Cc: Zhang Rui <rui.zhang@intel.com>
> > Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
> > Cc: Amit Kucheria <amit.kucheria@verdurent.com>
> > Cc: Jean Delvare <jdelvare@suse.com>
> > Cc: Guenter Roeck <linux@roeck-us.net>
> > Cc: Keith Busch <kbusch@kernel.org>
> > Cc: Jens Axboe <axboe@fb.com>
> > Cc: Christoph Hellwig <hch@lst.de>
> > Cc: Sagi Grimberg <sagi@grimberg.me>
> > Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
> > ---
> > * v2
> > - add deci_kelvin_to_millicelsius_with_offset() in linux/temperature.h
> > - stop including linux/temperature.h from linux/thermal.h
> >
> > include/linux/temperature.h | 51 +++++++++++++++++++++++++++++++++++++++++++++
> > 1 file changed, 51 insertions(+)
> > create mode 100644 include/linux/temperature.h
> >
> > diff --git a/include/linux/temperature.h b/include/linux/temperature.h
> > new file mode 100644
> > index 0000000..679e70a
> > --- /dev/null
> > +++ b/include/linux/temperature.h
> > @@ -0,0 +1,51 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
> > +#ifndef _LINUX_TEMPERATURE_H
> > +#define _LINUX_TEMPERATURE_H
>
> It sounds strange to create a temperature file just for a few conversion
> functions. Why not create an units.h file, so some more conversions
> could be added later (not necessarily related to temperature) ?
Fine with me.
> > +#include <linux/kernel.h>
> > +
> > +#define ABSOLUTE_ZERO_MILLICELSIUS -273150
> > +
> > +static inline long kelvin_to_millicelsius(long t)
>
> Why 'long' ?
There's no specific reason, but the existing DECI_KELVIN_TO_CELSIUS() in
linux/thermal.h converts to 'long'.
Do you prefer changing 'long' to 'int'?
> > +{
> > + return t * 1000 + ABSOLUTE_ZERO_MILLICELSIUS;
> > +}
> > +
> > +static inline long millicelsius_to_kelvin(long t)
> > +{
> > + return DIV_ROUND_CLOSEST(t - ABSOLUTE_ZERO_MILLICELSIUS, 1000);
>
> Please don't duplicate these operations, just do the conversion to the
> right unit and then call a single function.
>
> Replace the constant by macros like what we find in time64.h.
>
> eg.
> #define MILLICELSIUS_PER_CELCIUS 1000
How about this?
#define ABSOLUTE_ZERO_MILLICELSIUS -273150
static inline long milli_kelvin_to_millicelsius(long t)
{
return t + ABSOLUTE_ZERO_MILLICELSIUS;
}
static inline long millicelsius_to_milli_kelvin(long t)
{
return t - ABSOLUTE_ZERO_MILLICELSIUS;
}
#define MILLIDEGREE_PER_DEGREE 1000
#define MILLIDEGREE_PER_DECIDEGREE 100
static inline long kelvin_to_millicelsius(long t)
{
return milli_kelvin_to_millicelsius(t * MILLIDEGREE_PER_DEGREE);
}
static inline long millicelsius_to_kelvin(long t)
{
t = millicelsius_to_milli_kelvin(t);
return DIV_ROUND_CLOSEST(t, MILLIDEGREE_PER_DEGREE);
}
static inline long deci_kelvin_to_celsius(long t)
{
t = milli_kelvin_to_millicelsius(t * MILLIDEGREE_PER_DECIDEGREE);
return DIV_ROUND_CLOSEST(t, MILLIDEGREE_PER_DEGREE);
}
static inline long celsius_to_deci_kelvin(long t)
{
t = millicelsius_to_milli_kelvin(t * MILLIDEGREE_PER_DEGREE);
return DIV_ROUND_CLOSEST(t, MILLIDEGREE_PER_DECIDEGREE);
}
/**
* deci_kelvin_to_millicelsius_with_offset - convert Kelvin to Celsius
* @t: temperature value in decidegrees Kelvin
* @offset: difference between Kelvin and Celsius in millidegrees
*
* Return: temperature value in millidegrees Celsius
*/
static inline long deci_kelvin_to_millicelsius_with_offset(long t, long offset)
{
return t * MILLIDEGREE_PER_DECIDEGREE - offset;
}
static inline long deci_kelvin_to_millicelsius(long t)
{
return milli_kelvin_to_millicelsius(t * MILLIDEGREE_PER_DECIDEGREE);
}
static inline long millicelsius_to_deci_kelvin(long t)
{
t = millicelsius_to_milli_kelvin(t);
return DIV_ROUND_CLOSEST(t, MILLIDEGREE_PER_DECIDEGREE);
}
> So you can really do the cleanup in all the drivers, like removing:
OK. I'll try as much as possible.
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next prev parent reply other threads:[~2019-12-07 15:57 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-28 14:54 [PATCH v2 0/8] add header file for kelvin to/from Celsius conversion helpers Akinobu Mita
2019-11-28 14:54 ` [PATCH v2 1/8] " Akinobu Mita
2019-12-06 16:49 ` Daniel Lezcano
2019-12-07 15:57 ` Akinobu Mita [this message]
2019-11-28 14:54 ` [PATCH v2 2/8] ACPI: thermal: switch to use <linux/temperature.h> helpers Akinobu Mita
2019-11-28 14:54 ` [PATCH v2 3/8] platform/x86: asus-wmi: " Akinobu Mita
2019-11-28 14:54 ` [PATCH v2 4/8] platform/x86: intel_menlow: " Akinobu Mita
2019-11-28 15:02 ` Andy Shevchenko
2019-11-28 14:54 ` [PATCH v2 5/8] thermal: int340x: " Akinobu Mita
2019-11-28 14:54 ` [PATCH v2 6/8] thermal: intel_pch: " Akinobu Mita
2019-11-28 14:54 ` [PATCH v2 7/8] nvme: hwmon: " Akinobu Mita
2019-11-28 15:14 ` Guenter Roeck
2019-12-11 18:33 ` Keith Busch
2019-11-28 14:54 ` [PATCH v2 8/8] thermal: remove kelvin to/from Celsius conversion helpers from <linux/thermal.h> Akinobu Mita
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