linux-kernel - Re: [PATCH v2 1/3] units: Add SI metric prefix definitions

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Message-ID: <YL5B1tIPNpQiWrQ/@smile.fi.intel.com>
Date:   Mon, 7 Jun 2021 18:57:10 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Joe Perches <joe@...ches.com>
Cc:     linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jarkko Nikula <jarkko.nikula@...ux.intel.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        wsa@...nel.org
Subject: Re: [PATCH v2 1/3] units: Add SI metric prefix definitions

On Mon, Jun 07, 2021 at 08:43:02AM -0700, Joe Perches wrote:
> On Mon, 2021-06-07 at 18:23 +0300, Andy Shevchenko wrote:
> > Sometimes it's useful to have well-defined SI metric prefix to be used
> > to self-describe the formulas or equations.

...

> > +/* 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

> Somewhat surprisingly to me, this seems safe.
> 
> (though I suggest using UL and ULL rather than L and LL)

Okay.

> The only use of any of these seems to be:
> 
> sound/pcmcia/vx/vxp_ops.c:      [VX_MICRO]      = 0x0c,         // MICRO
> sound/pcmcia/vx/vxp_ops.c:              vx_outb(chip, MICRO, level);
> sound/pcmcia/vx/vxp_ops.c:                      vx_outb(chip, MICRO, vx_compute_mic_level(chip->mic_level));
> 
> and these vx_outb uses are themselves macros that prepend VX_ to the 2nd arg.

Is it a real issue there?

(Yes, I saw it, but I didn't check compilation in the assumption that units.h
 is not anyhow included in that file).

Okay, I have compiled it, no problems registered.

-- 
With Best Regards,
Andy Shevchenko