linux-kernel - Re: [PATCH] iio: kx022a: Fix acceleration value scaling

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Message-ID: <77b5f4a6-4012-4409-9034-419b852a783f@gmail.com>
Date:   Mon, 23 Oct 2023 09:24:39 +0300
From:   Matti Vaittinen <mazziesaccount@...il.com>
To:     Jagath Jog J <jagathjog1996@...il.com>
Cc:     Matti Vaittinen <matti.vaittinen@...rohmeurope.com>,
        Jonathan Cameron <jic23@...nel.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Mehdi Djait <mehdi.djait.k@...il.com>,
        linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] iio: kx022a: Fix acceleration value scaling

On 10/20/23 19:48, Jagath Jog J wrote:
> On Fri, Oct 20, 2023 at 5:39 PM Matti Vaittinen
> <mazziesaccount@...il.com> wrote:
>>
>> On 10/19/23 21:21, Jagath Jog J wrote:
>>> Hi Matti,
>>>
>>> On Thu, Oct 19, 2023 at 6:54 PM Matti Vaittinen
>>> <mazziesaccount@...il.com> wrote:
>>>>
> 
>>>> I did only very quick testing on KX022A and iio_generic_buffer. After
>>>> the patch the values seemed to be correct order of magnitude. Further
>>>> testing is appreciated :)
>>>
>>> Values are correct with this change, Thank you for fixing.
>>> Tested-by: Jagath Jog J <jagathjog1996@...il.com>
>>
>> Thanks a ton for testing! May I ask which component did you use (or did
>> you just use some 'simulated' regster values?)
> 
> Hi Matti,
> 
> I just simulated with the register values, Should the 'tested-by' tag only be
> provided after hardware testing?

I am not sure TBH. I didn't have a problem with your tag though, I was 
merely curious to hear about the IC usage :)

Now that you mentioned the tested-by tag usage, I started to wonder it 
as well. From pure SW/driver point of view the register value simulation 
is sufficient - but in practice we are not interested in whether the 
code works "in theory" - but whether the products do really work. This 
is something which includes handling of potential HW quircks and 
oddities - which are not always documented or known.

If we assume a case where someone is developing new gizmo and hits a bug 
which is in reality caused by some undocumented HW hiccup - then fixes 
with "tested-by" tags which are not actually tested on HW having this 
hiccup but using SW simulation - may be misleading.

The above is just some overall pondering - I am not too concerned on 
your tested-by tag :) Besides, it's cool you did the testing! I 
appreciate that! However, I wonder if there is some wider consensus 
whether the tests should be ran using real HW when tested-by tag is 
given. Jonathan, do you have any educated opinion on this?

> I referred to this driver because it's
> the most recent accelerometer driver that was merged.

Makes sense :) Thanks for replying!

Yours,
	-- Matti

-- 
Matti Vaittinen
Linux kernel developer at ROHM Semiconductors
Oulu Finland

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