linux-kernel - Re: [PATCH v1 6/9] hwmon: Add Nuvoton NCT6694 HWMON support

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Message-ID: <fe2a7f2b-6405-4be7-90b5-0490761908db@roeck-us.net>
Date: Tue, 29 Oct 2024 21:26:26 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Ming Yu <a0282524688@...il.com>, Jonathan Cameron <jic23@...nel.org>
Cc: Kalesh Anakkur Purayil <kalesh-anakkur.purayil@...adcom.com>,
 tmyu0@...oton.com, lee@...nel.org, linus.walleij@...aro.org, brgl@...ev.pl,
 andi.shyti@...nel.org, mkl@...gutronix.de, mailhol.vincent@...adoo.fr,
 andrew+netdev@...n.ch, davem@...emloft.net, edumazet@...gle.com,
 kuba@...nel.org, pabeni@...hat.com, wim@...ux-watchdog.org,
 jdelvare@...e.com, lars@...afoo.de, ukleinek@...nel.org,
 alexandre.belloni@...tlin.com, linux-kernel@...r.kernel.org,
 linux-gpio@...r.kernel.org, linux-i2c@...r.kernel.org,
 linux-can@...r.kernel.org, netdev@...r.kernel.org,
 linux-watchdog@...r.kernel.org, linux-hwmon@...r.kernel.org,
 linux-iio@...r.kernel.org, linux-pwm@...r.kernel.org,
 linux-rtc@...r.kernel.org
Subject: Re: [PATCH v1 6/9] hwmon: Add Nuvoton NCT6694 HWMON support

On 10/29/24 20:29, Ming Yu wrote:
> Dear Jonathan,
> 
> Thanks you for your comments,
> I tested your suggestion in both the MFD driver and the IIO driver, and
> the iio-hwmon bridge worked well.
> On the other hand, my requirements involve accessing thermal sensors,
> voltage sensors and tachometers, so I should implement it in this HWMON
> drive, right?
> 

Duplicate drivers for the same hardware is not acceptable.

I see that so far only pwm and fan control is implemented in the hwmon driver.
There is no public documentation for NCT6694, so it is difficult to evaluate the
chip's capabilities. The summary doesn't even mention fan speed readings, meaning
pretty much everything is guesswork.

Either case, I do see that you also implemented a pwm driver which _does_
duplicate hwmon functionality. Sorry, that is a no-go. Again, we can not have
multiple drivers controlling the same hardware. A pwm controller implemented
in a hwmon device is supposed to be limited to fan control. It looks like
the pwm controller implemented in the NCT6694 is a generic pwm controller.
It is not appropriate to have a hwmon driver for such a pwm controller.

Guenter