RE: [RFC v3 1/2] pinctrl: core: Add pinctrl_mux_gpio_request_enable

From: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
To: Linus Walleij <linus.walleij@linaro.org>
Cc: Geert Uytterhoeven <geert+renesas@glider.be>,
	Bartosz Golaszewski <bgolaszewski@baylibre.com>,
	"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
	Simon Horman <horms@verge.net.au>,
	Chris Paterson <Chris.Paterson2@renesas.com>,
	Biju Das <biju.das@bp.renesas.com>,
	Linux-Renesas <linux-renesas-soc@vger.kernel.org>
Subject: RE: [RFC v3 1/2] pinctrl: core: Add pinctrl_mux_gpio_request_enable
Date: Thu, 6 Dec 2018 09:47:06 +0000	[thread overview]
Message-ID: <TY1PR01MB177090970EE98AC699E22E3CC0A90@TY1PR01MB1770.jpnprd01.prod.outlook.com> (raw)
In-Reply-To: <CACRpkdbf+MpB24etuXUGypOwHUW_w4ECu-iFFT3aEB10wG0Huw@mail.gmail.com>

Hello Linus,

Thank you for your feedback!

> From: Linus Walleij <linus.walleij@linaro.org>
> Sent: 05 December 2018 21:46
> Subject: Re: [RFC v3 1/2] pinctrl: core: Add pinctrl_mux_gpio_request_enable
>
> On Tue, Nov 20, 2018 at 4:19 PM Fabrizio Castro
> <fabrizio.castro@bp.renesas.com> wrote:
>
> > Sometimes there is the need to change the muxing of a pin to make it
> > a GPIO without going through gpiolib.
> > This patch adds pinctrl_mux_gpio_request_enable to deal with this new
> > use case from code that has nothing to do with pinctrl.
>
> It has a lot to do with pinctrl I think, so I get confused by this
> commit message.

I can improve that

>
> >  extern int pinctrl_gpio_request(unsigned gpio);
> > +extern int pinctrl_mux_gpio_request_enable(unsigned gpio);
>
> What's wrong with just using the existing call
> pinctrl_gpio_request() right above your new one?
>
> It's not like we're reference counting or something, it's just
> a callback. Sprinkle some comments to show what's going
> on.

I tried that, and it was working for me, then something changed lately
in gpiolib that broke that solution, and Geert picked it up on his end.
Please see this:
https://patchwork.kernel.org/patch/10671325/

This patch was made to overcome the problems of the previous patch.

>
> If you for some reason need a new call for this specific
> use case, it needs to be named after the use case,
> like pinctrl_gpio_request_for_irq()
> so it is obvious what the function is doing.

I can do that, but I would like to hear from Geert first, no point in going
around in circle if this solution is not acceptable to him.

Geert, what do you think?

Thanks!
Fab

>
> Yours,
> Linus Walleij

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