Re: [PATCH v7 06/13] pwm: add support for sl28cpld PWM controller

From: Lee Jones <lee.jones@linaro.org>
To: Michael Walle <michael@walle.cc>
Cc: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>,
	linux-gpio@vger.kernel.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-hwmon@vger.kernel.org,
	linux-pwm@vger.kernel.org, linux-watchdog@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	"Linus Walleij" <linus.walleij@linaro.org>,
	"Bartosz Golaszewski" <bgolaszewski@baylibre.com>,
	"Rob Herring" <robh+dt@kernel.org>,
	"Jean Delvare" <jdelvare@suse.com>,
	"Guenter Roeck" <linux@roeck-us.net>,
	"Thierry Reding" <thierry.reding@gmail.com>,
	"Wim Van Sebroeck" <wim@linux-watchdog.org>,
	"Shawn Guo" <shawnguo@kernel.org>, "Li Yang" <leoyang.li@nxp.com>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Jason Cooper" <jason@lakedaemon.net>,
	"Marc Zyngier" <maz@kernel.org>,
	"Mark Brown" <broonie@kernel.org>,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	"Andy Shevchenko" <andriy.shevchenko@linux.intel.com>,
	"Catalin Marinas" <catalin.marinas@arm.com>,
	"Will Deacon" <will@kernel.org>, "Pavel Machek" <pavel@ucw.cz>
Subject: Re: [PATCH v7 06/13] pwm: add support for sl28cpld PWM controller
Date: Thu, 13 Aug 2020 09:21:18 +0100	[thread overview]
Message-ID: <20200813082118.GJ4354@dell> (raw)
In-Reply-To: <2ca0a3a3f03a1f5b9b2777738824123b@walle.cc>

On Mon, 10 Aug 2020, Michael Walle wrote:

> Am 2020-08-10 09:13, schrieb Lee Jones:
> > On Fri, 07 Aug 2020, Michael Walle wrote:
> > 
> > > Hi Uwe, Hi Lee,
> > > 
> > > Am 2020-08-06 10:40, schrieb Uwe Kleine-König:
> > > > On Mon, Aug 03, 2020 at 11:35:52AM +0200, Michael Walle wrote:
> > > > > diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
> > > > > index 7dbcf6973d33..a0d50d70c3b9 100644
> > > > > --- a/drivers/pwm/Kconfig
> > > > > +++ b/drivers/pwm/Kconfig
> > > > > @@ -428,6 +428,16 @@ config PWM_SIFIVE
> > > > >  	  To compile this driver as a module, choose M here: the module
> > > > >  	  will be called pwm-sifive.
> > > > >
> > > > > +config PWM_SL28CPLD
> > > > > +	tristate "Kontron sl28cpld PWM support"
> > > > > +	select MFD_SIMPLE_MFD_I2C
> > > >
> > > > Is it sensible to present this option to everyone? Maybe
> > > >
> > > > 	depends on SOME_SYMBOL_ONLY_TRUE_ON_SL28CPLD || COMPILE_TEST
> > > 
> > > Because there is now no real MFD driver anymore, there is also
> > > no symbol for that. The closest would be ARCH_ARM64 but I don't
> > > think that is a good idea.
> > > 
> > > Lee, what do you think about adding a symbol to the MFD, which
> > > selects MFD_SIMPLE_MFD_I2C but doesn't enable any C modules?
> > > 
> > > I.e.
> > > config MFD_SL28CPLD
> > >     tristate "Kontron sl28cpld"
> > >     select MFD_SIMPLE_MFD_I2C
> > >     help
> > >       Say yes here to add support for the Kontron sl28cpld board
> > >       management controller.
> > > 
> > > Then all the other device driver could depend on the MFD_SL28CPLD
> > > symbol.
> > 
> > You want to add a virtual symbol to prevent having to present a real
> > one?  How is that a reasonable solution?
> 
> (1) Its a symbol on which all sl28cpld will depend on. Thus they will
>     all be hidden if that is not set.
> (2) the drivers itself wouldn't need to depend on MFD_SIMPLE_MFD_I2C,
>     which is more correct, because they don't have anything to do with
>     i2c.

Yes, okay.

-- 
Lee Jones [李琼斯]
Senior Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
Follow Linaro: Facebook | Twitter | Blog