Re: [PATCH] adjtimex: PPM scaling is by 2^-16

From: Jeff Epler
Date: Fri Jan 02 2015 - 16:15:32 EST


On Fri, Jan 02, 2015 at 05:39:17PM +0100, Laurent Georget wrote:
> + long freq; /* Frequency offset, in units of 2^-16 PPM
> + (parts per million) (see NOTES below) */
...
> +.SH NOTES
> +In struct
> +.IR timex ,
> +.IR freq ,
> +.IR ppsfreq ,
> +and
> +.I stabil
> +are PPM (parts per million) with a 16-bits fractional part, which means that a
> +value of 1 in one of those fields actually means 2^-16 PPM, and 2^16=65535 is
> +1 PPM. This is the case for both input values (in the case of
> +.IR freq )
> +and output values.

I appreciate the addition of the NOTES section, this is likely to be
unclear to first-time readers and that section should clear it up
nicely. Giving the definition of PPM as "parts per million" is good
too.

However, the patch got line-wrapped again (I fixed it manually above).
With line-wrapped fix, consider it

Reviewed-by: Jeff Epler <jepler@xxxxxxxxxxxxxx>

hm, as a separate issue, "ppm" seems to typically be written in
lowercase. see e.g., http://en.wikipedia.org/wiki/Parts-per_notation

Jeff
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/