netdev - Re: [PATCH v10 1/7] mfd: Add core driver for Nuvoton NCT6694

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Message-ID: <CAOoeyxWpYmcg1_FBXYqDfMi28R5ZXp2Sk2PhUo=cL10Nn3iVEw@mail.gmail.com>
Date: Fri, 2 May 2025 17:04:19 +0800
From: Ming Yu <a0282524688@...il.com>
To: Lee Jones <lee@...nel.org>
Cc: 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, 
	Ming Yu <tmyu0@...oton.com>
Subject: Re: [PATCH v10 1/7] mfd: Add core driver for Nuvoton NCT6694

Lee Jones <lee@...nel.org> 於 2025年5月2日 週五 下午4:08寫道：
>
...
> > > > +static const struct mfd_cell nct6694_devs[] = {
> > > > +     MFD_CELL_BASIC("nct6694-gpio", NULL, NULL, 0, 0),
> > > > +     MFD_CELL_BASIC("nct6694-gpio", NULL, NULL, 0, 1),
> > > > +     MFD_CELL_BASIC("nct6694-gpio", NULL, NULL, 0, 2),
> > > > +     MFD_CELL_BASIC("nct6694-gpio", NULL, NULL, 0, 3),
> > > > +     MFD_CELL_BASIC("nct6694-gpio", NULL, NULL, 0, 4),
> > > > +     MFD_CELL_BASIC("nct6694-gpio", NULL, NULL, 0, 5),
> > > > +     MFD_CELL_BASIC("nct6694-gpio", NULL, NULL, 0, 6),
> > > > +     MFD_CELL_BASIC("nct6694-gpio", NULL, NULL, 0, 7),
> > > > +     MFD_CELL_BASIC("nct6694-gpio", NULL, NULL, 0, 8),
> > > > +     MFD_CELL_BASIC("nct6694-gpio", NULL, NULL, 0, 9),
> > > > +     MFD_CELL_BASIC("nct6694-gpio", NULL, NULL, 0, 10),
> > > > +     MFD_CELL_BASIC("nct6694-gpio", NULL, NULL, 0, 11),
> > > > +     MFD_CELL_BASIC("nct6694-gpio", NULL, NULL, 0, 12),
> > > > +     MFD_CELL_BASIC("nct6694-gpio", NULL, NULL, 0, 13),
> > > > +     MFD_CELL_BASIC("nct6694-gpio", NULL, NULL, 0, 14),
> > > > +     MFD_CELL_BASIC("nct6694-gpio", NULL, NULL, 0, 15),
> > >
> > > These are all identical.
> > >
> > > I thought you were going to use PLATFORM_DEVID_AUTO?  In fact, you are
> > > already using PLATFORM_DEVID_AUTO since you are calling
> > > mfd_add_hotplug_devices().  So you don't need this IDs.
> > >
> > > MFD_CELL_NAME() should do.
> > >
> >
> > Yes, it uses PLATFORM_DEVID_AUTO, but in my implementation, the
> > sub-devices use cell->id instead of platform_device->id, so it doesn't
> > affect the current behavior.
> > However, if you think there's a better approach or that this should be
> > changed for consistency or correctness, I'm happy to update it, please
> > let me know your recommendation.
> >
> > When using MFD_CELL_NAME(), the platform_device->id for the GPIO
> > devices is assigned values from 1 to 16, and for the I2C devices from
> > 1 to 6, but I need the ID offset to start from 0 instead.
>
> Oh no, don't do that.  mfd_cell isn't supposed to be used outside of MFD.
>
> Just use the platform_device id-- if you really need to start from 0.
>
> As an aside, I'm surprised numbering starts from 1.
>

OK, I will use platform_device->id instead. However, I'm still unsure
why the ID starts from1.

Additionally, I noticed that when calling mfd_add_devices()
separately, the IDs are also assigned consecutively (e.g., GPIO: 1~16,
I2C: 17~22, ...).

Do you have any recommendations on how I should implement this?


Thanks,
Ming