linux-kernel - Re: [PATCH] iio: st_lsm6dsx: Replace scnprintf with sysfs

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Message-ID: <20250702163342.00003c66@huawei.com>
Date: Wed, 2 Jul 2025 16:33:42 +0100
From: Jonathan Cameron <Jonathan.Cameron@...wei.com>
To: David Lechner <dlechner@...libre.com>
CC: Andy Shevchenko <andriy.shevchenko@...el.com>, Akshay Bansod
	<akbansd@...il.com>, Lorenzo Bianconi <lorenzo@...nel.org>, "Jonathan
 Cameron" <jic23@...nel.org>, Nuno Sá <nuno.sa@...log.com>,
	Andy Shevchenko <andy@...nel.org>,
	<linux-kernel-mentees@...ts.linuxfoundation.org>,
	<linux-iio@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] iio: st_lsm6dsx: Replace scnprintf with sysfs_emit

On Wed, 2 Jul 2025 10:04:23 -0500
David Lechner <dlechner@...libre.com> wrote:

> On 7/2/25 9:55 AM, Andy Shevchenko wrote:
> > On Wed, Jul 02, 2025 at 09:16:51AM -0500, David Lechner wrote:  
> >> On 7/2/25 8:58 AM, Akshay Bansod wrote:  
> >>> Update the sysfs interface for sampling frequency and scale attributes.
> >>> Replace `scnprintf()` with `sysfs_emit_at()` which is PAGE_SIZE-aware
> >>> and recommended for use in sysfs.  
> > 
> > ...
> >   
> >>> +		len += sysfs_emit_at(buf, len, "%d.%03d ",
> >>>  				 odr_table->odr_avl[i].milli_hz / 1000,
> >>>  				 odr_table->odr_avl[i].milli_hz % 1000);  
> >>
> >> Let's keep checkpatch happy and change the indent of the wrapped lines to
> >> line up with ( since the ( moved.  
> > 
> > While I see the point, wouldn't be better to have 1000 replaced with MILLI
> > at the same time?
> >   
> 
> For anything with 3 zeros, I don't consider MILLI better (or worse).
> Science shows that the average human can easily see 3 or 4 things
> without having to count them [1]. So it is only when we start getting
> more 0s than that is when I think we should be picky about using macros
> instead.
> 
> And in this particular case, we are converting milli to micro so `1000`
> should be replaced by `(MICRO / MILLI)` if we are going to do that.
No we aren't.

This one is converting from milli_hz to hz + sticking to milli for the decimal
part.

Lots of other IIO cases where you would have been right, but I think not here.
> 
> [1]: https://www.scientificamerican.com/article/your-brain-finds-it-easy-to-size-up-four-objects-but-not-five-heres-why/
> 
>