linux-kernel - Re: [PATCH v8 1/7] mfd: Add core driver for Nuvoton NCT6694

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Message-ID: <CAOoeyxVVgHGkH5ajQT0NGNPv7FmVPLzuZtGjCiF7mRRto70aAg@mail.gmail.com>
Date: Mon, 7 Apr 2025 10:25:58 +0800
From: Ming Yu <a0282524688@...il.com>
To: Lee Jones <lee@...nel.org>
Cc: tmyu0@...oton.com, 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, 
	linux@...ck-us.net, jdelvare@...e.com, 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-rtc@...r.kernel.org, linux-usb@...r.kernel.org
Subject: Re: [PATCH v8 1/7] mfd: Add core driver for Nuvoton NCT6694

Lee Jones <lee@...nel.org> 於 2025年4月4日 週五 下午10:21寫道：
>
> > ...
> > > > > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x1),
> > > > >
> > > > > IDs are usually given in base-10.
> > > > >
> > > >
> > > > Fix it in v9.
> > > >
> > > > > Why are you manually adding the device IDs?
> > > > >
> > > > > PLATFORM_DEVID_AUTO doesn't work for you?
> > > > >
> > > >
> > > > I need to manage these IDs to ensure that child devices can be
> > > > properly utilized within their respective modules.
> > >
> > > How?  Please explain.
> > >
> > > This numbering looks sequential and arbitrary.
> > >
> > > What does PLATFORM_DEVID_AUTO do differently such that it is not useful?
> > >
> >
> > As far as I know, PLATFORM_DEVID_AUTO assigns dynamic IDs to devices,
> > but I need fixed IDs.
> > For example, the GPIO driver relies on these IDs to determine the
> > group, allowing the firmware to identify which GPIO group to operate
> > on through the API.
>
> PLATFORM_DEVID_AUTO will allocate IDs 0 through 16, the same as you've
> done here.  These lines do not have any differentiating attributes, so
> either way we are not allocating specific IDs to specific pieces of the
> H/W.  I still do not understand why you need to allocate them manually.
>

I'm using PLATFORM_DEVID_AUTO to allocate child device IDs with
MFD_CELL_NAME(), like this:

static const struct mfd_cell nct6694_dev[] = {
    MFD_CELL_NAME("nct6694-gpio"),
    MFD_CELL_NAME("nct6694-gpio"),
    ......
    MFD_CELL_NAME("nct6694-gpio"),
    MFD_CELL_NAME("nct6694-i2c"),
    MFD_CELL_NAME("nct6694-i2c"),
    ......
    MFD_CELL_NAME("nct6694-i2c"),
    ......
};

For example, the device IDs retrieved in gpio-nct6694.c is 1~16, and
i2c-nct6694.c is 17~22. Does this mean each driver should
independently handle its dynamically assigned IDs?
Additionally, I originally referred to cgbc-core.c with i2c-cgbc.c,
and ab8500-core.c with pwm-ab8500.c for associating child devices. Do
you think this approach is appropriate in my case?


Thanks,
Ming