From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Cc: linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org,
Mika Westerberg <mika.westerberg@linux.intel.com>,
wsa@kernel.org
Subject: Re: [PATCH resend v1 1/3] units: Add SI metric prefix definitions
Date: Mon, 7 Jun 2021 17:24:44 +0300 [thread overview]
Message-ID: <YL4sLLQ/Y+GafaeH@smile.fi.intel.com> (raw)
In-Reply-To: <0466dab7-f2d2-3b7c-52a6-a12a6b09a67f@linux.intel.com>
On Mon, Jun 07, 2021 at 03:33:31PM +0300, Jarkko Nikula wrote:
> On 6/3/21 7:04 PM, Andy Shevchenko wrote:
> > Sometimes it's useful to have well-defined SI metric prefix to be used
> > to self-describe the formulas or equations.
> >
> > List most popular ones in the units.h.
...
> > +/* Metric prefixes in accordance with Système international (d'unités) */
> > +#define PETA 1000000000000000LL
> > +#define TERA 1000000000000LL
> > +#define GIGA 1000000000L
> > +#define MEGA 1000000L
> > +#define KILO 1000L
> > +#define HECTO 100L
> > +#define DECA 10L
> > +#define DECI 10L
> > +#define CENTI 100L
> > +#define MILLI 1000L
> > +#define MICRO 1000000L
> > +#define NANO 1000000000L
> > +#define PICO 1000000000000LL
> > +#define FEMTO 1000000000000000LL
>
> For me milli is always 1/1000.
For me as well. Kernel does not operate with float point numbers.
That's why it's ordered like this.
> Might lead to confusion with these defines if
> idea is to multiply with KILO but divide with MILLI?
If the author of the hypothetical driver doesn't understand this, maybe
they can ask first, but I am an optimist here and I assume that whoever
writes the driver for a sensor / etc has a minimum education to see
what's needed for the certain case.
--
With Best Regards,
Andy Shevchenko
next prev parent reply other threads:[~2021-06-07 14:24 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-03 16:04 [PATCH resend v1 1/3] units: Add SI metric prefix definitions Andy Shevchenko
2021-06-03 16:04 ` [PATCH resend v1 2/3] i2c: designware: Use DIV_ROUND_CLOSEST() macro Andy Shevchenko
2021-06-03 16:04 ` [PATCH resend v1 3/3] i2c: designware: Fix indentation in the header Andy Shevchenko
2021-06-07 12:33 ` [PATCH resend v1 1/3] units: Add SI metric prefix definitions Jarkko Nikula
2021-06-07 14:24 ` Andy Shevchenko [this message]
2021-06-07 14:35 ` Andy Shevchenko
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