linux-kernel - Re: [PATCH v2 1/6] math.h: Add macros for rounding to the closest value

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Message-ID: <9c41f6b7-6b06-cd5b-74bd-24873c4beaf7@ti.com>
Date: Tue, 27 Aug 2024 16:57:17 +0530
From: Devarsh Thakkar <devarsht@...com>
To: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
CC: <mchehab@...nel.org>, <hverkuil-cisco@...all.nl>,
        <linux-media@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <sebastian.fricke@...labora.com>, <linux-doc@...r.kernel.org>,
        <praneeth@...com>, <nm@...com>, <vigneshr@...com>, <s-jain1@...com>,
        <r-donadkar@...com>, <b-brnich@...com>, <detheridge@...com>,
        <p-mantena@...com>, <vijayp@...com>, <andi.shyti@...ux.intel.com>,
        <nicolas@...fresne.ca>, <jirislaby@...nel.org>, <davidgow@...gle.com>,
        <dlatypov@...gle.com>, <corbet@....net>, <broonie@...nel.org>,
        <jani.nikula@...el.com>, <rdunlap@...radead.org>,
        <nik.borisov@...e.com>, <Dave.Martin@....com>
Subject: Re: [PATCH v2 1/6] math.h: Add macros for rounding to the closest
 value

Hi Andy,

Thanks for the review.

On 26/08/24 23:14, Andy Shevchenko wrote:
> On Mon, Aug 26, 2024 at 08:38:17PM +0530, Devarsh Thakkar wrote:
>> Add below rounding related macros:
>>
>> round_closest_up(x, y) : Rounds x to the closest multiple of y where y is a
>> power of 2, with a preference to round up in case two nearest values are
>> possible.
>>
>> round_closest_down(x, y) : Rounds x to the closest multiple of y where y is
>> a power of 2, with a preference to round down in case two nearest values
>> are possible.
>>
>> roundclosest(x, y) : Rounds x to the closest multiple of y, this macro
>> should generally be used only when y is not multiple of 2 as otherwise
>> round_closest* macros should be used which are much faster.
> 
> I understand the point, but if you need to send a v3, please explain
> the equivalency between roundclosest() and one (or both?) of the
> round_closest_*() in case the argument is power-of-2.
> 

The equivalency between roundclosest w.r.t round_closest is same as
equivalency between existing macros rounddown w.r.t round_down. Functionally
both are same but the former is recommended to be used only for the scenario
where multiple is not power of 2 and latter is faster but is strictly for the
scenario where multiple is power of 2. I think the same is already summarized
well in commit message and further elaborated in the patch itself as part of
header file comments [1] so I personally don't think any update is required
w.r.t this.

[1]: https://lore.kernel.org/all/20240826150822.4057164-2-devarsht@ti.com

Regards
Devarsh