linux-kernel - Re: [PATCH v7 6/8] math.h Add macros to round to closest specified power of 2

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Date: Sat, 11 May 2024 23:11:14 +0530
From: Devarsh Thakkar <devarsht@...com>
To: Jani Nikula <jani.nikula@...el.com>,
        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>,
        <benjamin.gaignard@...labora.com>, <sebastian.fricke@...labora.com>,
        <akpm@...ux-foundation.org>, <gregkh@...uxfoundation.org>,
        <adobriyan@...il.com>, <p.zabel@...gutronix.de>, <airlied@...il.com>,
        <daniel@...ll.ch>, <dri-devel@...ts.freedesktop.org>,
        <laurent.pinchart@...asonboard.com>, <praneeth@...com>, <nm@...com>,
        <vigneshr@...com>, <a-bhatia1@...com>, <j-luthra@...com>,
        <b-brnich@...com>, <detheridge@...com>, <p-mantena@...com>,
        <vijayp@...com>, <andrzej.p@...labora.com>, <nicolas@...fresne.ca>
Subject: Re: [PATCH v7 6/8] math.h Add macros to round to closest specified
 power of 2

Hi Jani,

Thanks for the quick review.

On 10/05/24 20:45, Jani Nikula wrote:

[...]
> Moreover, I think the naming of round_up() and round_down() should have
> reflected the fact that they operate on powers of 2. It's unfortunate
> that the difference to roundup() and rounddown() is just the underscore!
> That's just a trap.
> 
> So let's perhaps not repeat the same with round_closest_up() and
> round_closest_down()?
> 

Yes the naming is inspired by existing macros i.e. round_up, round_down
(which round up/down to next pow of 2) and DIV_ROUND_CLOSEST (which
round the divided value to closest value) and there are already a lot of
users for these API's :

  linux-next git:(heads/next-20240509) ✗ grep -nr round_up drivers | wc
    730    4261   74775

  linux-next git:(heads/next-20240509) ✗ grep -nr round_down drivers | wc
    226    1293   22194

 linux-next git:(heads/next-20240509) ✗ grep -nr DIV_ROUND_CLOSEST
drivers | wc
   1207    7461  111822


so I thought to align with existing naming convention assuming
developers are already familiar with this.

But if a wider consensus is to go with a newer naming convention then I
am open to it, although a challenge there would be to keep it short. For
e.g. this one is already 3 words, if we go with more explicit
"round_closest_up_pow_2" it looks quite long in my opinion :) .

Regards
Devarsh