linux-kernel - Re: [PATCH 0/2] Introduce new iio resolution standard attribute

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Message-ID: <7b0599b5-15ae-7104-5298-805b6377f39d@axis.com>
Date: Mon, 18 Dec 2023 16:08:00 +0100
From: Mårten Lindahl <martenli@...s.com>
To: Jonathan Cameron <jic23@...nel.org>
Cc: Lars-Peter Clausen <lars@...afoo.de>, linux-iio@...r.kernel.org,
 linux-kernel@...r.kernel.org, kernel@...s.com
Subject: Re: [PATCH 0/2] Introduce new iio resolution standard attribute

On 12/17/23 15:10, Jonathan Cameron wrote:
> On Fri, 15 Dec 2023 13:43:03 +0100
> Mårten Lindahl <marten.lindahl@...s.com> wrote:
>
>> This patch introduces a new IIO standard attribute to set the bit
>> resolution of the data *_raw readings dynamically using sysfs.
>>
>> The VCNL4040/4200 proximity/ambient light sensors support 12-bit
>> (default) and 16-bit ADC resolutions. This can be dynamically changed,
>> so to support this with the standard iio channel configuration a new iio
>> attribute should be added.
>>
>> The VCNL4040 devices will use this for setting proximity high definition
>> (16-bit resolution).
>>
>> Signed-off-by: Mårten Lindahl <marten.lindahl@...s.com>
> Hi Mårten,
>
> What is the use case?  We've had lots of devices capable of doing this
> sort of resolution change, but never yet come up with a reason to do so for
> the sysfs interfaces on the basis the overhead of the sysfs interfaces is
> high enough the best bet is almost always to use the highest available resolution
> and don't worry that the read takes a little longer.
>
> Jonathan

Hi Jonathan!

My use case probably does not differ from others, in that 12 bits does 
not give enough precision. So it's just a dynamic feature that the 
sensor has, but as you suggest to hard code this to the highest works 
fine for me. I just didn't feel confident enough to do that :)

I'll make a single patch for this change instead. Thanks!

Kind regards

Mårten

>
>> ---
>> Mårten Lindahl (2):
>>        iio: core: Introduce resolution standard attribute
>>        iio: light: vcnl4000: Add ps high definition for vcnl4040
>>
>>   drivers/iio/industrialio-core.c |  1 +
>>   drivers/iio/light/vcnl4000.c    | 87 ++++++++++++++++++++++++++++++++++++++++-
>>   include/linux/iio/types.h       |  1 +
>>   3 files changed, 87 insertions(+), 2 deletions(-)
>> ---
>> base-commit: a39b6ac3781d46ba18193c9dbb2110f31e9bffe9
>> change-id: 20231212-vcnl4000-ps-hd-38d42abf9095
>>
>> Best regards,