linux-kernel - Re: [PATCH v4 3/3] mfd: vortex: implement new driver for Vortex southbridges

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Message-ID: <20250903140115.GC2764654@google.com>
Date: Wed, 3 Sep 2025 15:01:15 +0100
From: Lee Jones <lee@...nel.org>
To: Marcos Del Sol Vives <marcos@...a.pet>
Cc: linux-kernel@...r.kernel.org, Linus Walleij <linus.walleij@...aro.org>,
	Bartosz Golaszewski <brgl@...ev.pl>,
	Michael Walle <mwalle@...nel.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>, linux-gpio@...r.kernel.org,
	linux-pci@...r.kernel.org
Subject: Re: [PATCH v4 3/3] mfd: vortex: implement new driver for Vortex
 southbridges

On Wed, 03 Sep 2025, Marcos Del Sol Vives wrote:

> El 03/09/2025 a las 9:21, Lee Jones escribió:
> >>>> +static const struct mfd_cell vortex_dx_sb_cells[] = {
> >>>> +	{
> >>>> +		.name		= "vortex-gpio",
> >>>> +		.resources	= vortex_dx_gpio_resources,
> >>>> +		.num_resources	= ARRAY_SIZE(vortex_dx_gpio_resources),
> >>>> +	},
> >>>> +};
> >>>
> >>> It's not an MFD until you have more than one device.
> >>
> >> Same as above.
> > 
> > It will not be accepted with only a single device (SFD?).
> > 
> 
> I've been working on making all the changes, except this one.
> 
> If you prefer, I can either implement the watchdog now, add it on this

Yes, please implement the WDT now.

> patch series and thus make it a proper MFD (at the cost of delaying
> even further the GPIO inclusion), or keep the struct mfd_cell array
> as a single-element array and implement the watchdog later on another
> merge request, using that very same array.
> 
> I am however not okay with wasting my time rewriting that to bypass
> the MFD API for this, so I can waste even more time later
> implementing again the MFD API, just because linguistically
> one (right now) is technically not "multi".

I don't get this.  If you implement the WDT now, you will be "multi", so
what are you protesting against?

> That seems very unreasonable, specially when it wouldn't be a first
> since at least these other devices are also using MFD with a single
> device:
> 
>   - 88pm80

% grep name drivers/mfd/88pm800.c
	.name = "88pm80x-rtc",
	.name = "88pm80x-onkey",
	.name = "88pm80x-regulator",
	.name = "88pm800",

>   - 88pm805

% grep name drivers/mfd/88pm805.c       
	.name = "88pm80x-codec",
	.name = "88pm805",

>   - at91-usart

% grep NAME drivers/mfd/at91-usart.c
	MFD_CELL_NAME("at91_usart_spi");
	MFD_CELL_NAME("atmel_usart_serial");

>   - stw481x

* Copyright (C) 2013 ST-Ericsson SA

>   - vx855

* Copyright (C) 2009 VIA Technologies, Inc.

>   - wm8400

* Copyright 2008 Wolfson Microelectronics PLC.

>   - zynqmp (last changed in 2024, so certainly not legacy!)

This should _not_ be using the MFD API at all!

> And probably others since I did not look too deep into it.
> 
> Greetings,
> Marcos
> 

-- 
Lee Jones [李琼斯]