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

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Message-ID: <b11dcd50-a87e-47ff-b406-776e432f07bd@orca.pet>
Date: Wed, 3 Sep 2025 16:48:15 +0200
From: Marcos Del Sol Vives <marcos@...a.pet>
To: Lee Jones <lee@...nel.org>
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

El 03/09/2025 a las 16:01, Lee Jones escribió:
>> 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 GPIO is something required to perform the poweroff sequence, a must
for any machine, while WDT is just a "nice to have".

Implementing now the WDT just because of a linguistic preference means
delaying something more important in favour of a "nice to have".

>> 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",

If you open the file, you'll see it uses five single-element arrays.

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

Same as above.

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

Has two single-element arrays. It registers one or the other, never both
(just like my patch does!)

>>   - stw481x
> 
> * Copyright (C) 2013 ST-Ericsson SA
> 
>>   - vx855
> 
> * Copyright (C) 2009 VIA Technologies, Inc.
> 
>>   - wm8400
> 
> * Copyright 2008 Wolfson Microelectronics PLC.
> 

To my knowledge the definition of "multi" has not been changed
since any of those years.