linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: "Vaittinen, Matti" <Matti.Vaittinen@fi.rohmeurope.com>
To: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Matti Vaittinen <mazziesaccount@gmail.com>,
	Liam Girdwood <lgirdwood@gmail.com>,
	Mark Brown <broonie@kernel.org>, Jiri Kosina <trivial@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Yury Norov <yury.norov@gmail.com>,
	Kumar Kartikeya Dwivedi <memxor@gmail.com>,
	Rasmus Villemoes <linux@rasmusvillemoes.dk>,
	Geert Uytterhoeven <geert+renesas@glider.be>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/4] bitops: Add single_bit_set()
Date: Mon, 22 Nov 2021 12:42:21 +0000	[thread overview]
Message-ID: <2c22b52f-9a1f-06f5-f008-d568096f5c4d@fi.rohmeurope.com> (raw)
In-Reply-To: <YZt+x2moR632x///@smile.fi.intel.com>

On 11/22/21 13:28, Andy Shevchenko wrote:
> On Mon, Nov 22, 2021 at 01:03:25PM +0200, Matti Vaittinen wrote:
>> There are cases when it is useful to check a bit-mask has only one bit
>> set. Add a generic helper for it instead of baking own one for each
>> user.
>>
>> Signed-off-by: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
>> ---
>> I am not at all sure what would be the best place for this. Please let
>> me know if you think some other file would be more appropriate.
> 
> So, you decided to reinvent hamming weight...
> Please, drop this patch and use corresponding hweight() call.
> 

Thanks Andy.

There are few differences to hamming weight here. We scan only given 
amount of bits - and we will end scanning immediately when we hit second 
set bit. Oh, and obviously we only return information whether there is 
exactly one bit set. So no, this is not hamming weight().

Yet, I think you are correct. My use-case does not warrant adding this. 
I have no need for scanning only certain amount of bits.

I think I actually tried using hweight() at some point but don't really 
remember why I rolled the single_bit_set. (I remember the hweight() 
usage because I had to do some googling as I had never heard term 
hamming weight before).

I'll see how it works out and if (when) it does I'll respin the series 
w/o this as you suggested. So thanks.

--Matti

-- 
The Linux Kernel guy at ROHM Semiconductors

Matti Vaittinen, Linux device drivers
ROHM Semiconductors, Finland SWDC
Kiviharjunlenkki 1E
90220 OULU
FINLAND

~~ this year is the year of a signature writers block ~~

  reply	other threads:[~2021-11-22 12:42 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-22 11:03 [PATCH 0/4] Provide event map helper for regulator drivers Matti Vaittinen
2021-11-22 11:03 ` [PATCH 1/4] bitops: Add single_bit_set() Matti Vaittinen
2021-11-22 11:28   ` Andy Shevchenko
2021-11-22 12:42     ` Vaittinen, Matti [this message]
2021-11-22 12:57       ` Andy Shevchenko
2021-11-22 13:00         ` Andy Shevchenko
2021-11-22 13:18         ` Vaittinen, Matti
2021-11-23 10:42           ` David Laight
2021-11-23 10:47             ` Andy Shevchenko
2021-11-23 10:58               ` David Laight
2021-11-23 13:43                 ` 'Andy Shevchenko'
2021-11-23 14:36                   ` David Laight
2021-11-23 11:42             ` Vaittinen, Matti
2021-11-22 17:54         ` Yury Norov
2021-11-22 19:56           ` Andy Shevchenko
2021-11-23  7:51             ` Yury Norov
2021-11-23  5:26           ` Vaittinen, Matti
2021-11-23  7:33             ` Yury Norov
2021-11-23  9:03               ` Andy Shevchenko
2021-11-23  9:10                 ` Geert Uytterhoeven
2021-11-22 11:03 ` [PATCH 2/4] regulators: Add regulator_err2notif() helper Matti Vaittinen
2021-11-22 11:04 ` [PATCH 3/4] regulators: irq_helper: Provide helper for trivial IRQ notifications Matti Vaittinen
2021-11-22 11:48   ` Andy Shevchenko
2021-11-22 12:44     ` Vaittinen, Matti
2021-11-22 11:04 ` [PATCH 4/4] regulator: Drop unnecessary struct member Matti Vaittinen

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=2c22b52f-9a1f-06f5-f008-d568096f5c4d@fi.rohmeurope.com \
    --to=matti.vaittinen@fi.rohmeurope.com \
    --cc=akpm@linux-foundation.org \
    --cc=andriy.shevchenko@linux.intel.com \
    --cc=broonie@kernel.org \
    --cc=geert+renesas@glider.be \
    --cc=lgirdwood@gmail.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux@rasmusvillemoes.dk \
    --cc=mazziesaccount@gmail.com \
    --cc=memxor@gmail.com \
    --cc=trivial@kernel.org \
    --cc=yury.norov@gmail.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).