linux-kernel - Re: [RFC/PATCH] pinctrl: sh-pfc: Accept standard function, pins and groups properties

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Date:	Wed, 4 Feb 2015 09:40:48 +0100
From:	Linus Walleij <linus.walleij@...aro.org>
To:	Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>,
	Sascha Hauer <kernel@...gutronix.de>
Cc:	Niklas Söderlund <niso@....se>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-sh@...r.kernel.org" <linux-sh@...r.kernel.org>,
	Magnus Damm <magnus.damm@...il.com>
Subject: Re: [RFC/PATCH] pinctrl: sh-pfc: Accept standard function, pins and
 groups properties

On Tue, Jan 27, 2015 at 9:31 PM, Laurent Pinchart
<laurent.pinchart+renesas@...asonboard.com> wrote:

> The "function", "pins" and "groups" pinmux and pinctrl properties have
> been standardized. Support them in addition to the custom "renesas,*"
> properties. New-style and old-style properties can't be mixed in DT.
>
> Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>
(...)

>> Would be nice if the PFC driver could be augmented to also accept the
>> now standard bindings "groups" and "function" simply :) we're adding parse
>> functions for those to the core.
>
> Something like this ?

Yes :)

> Please note two differences between the Renesas PFC bindings and the standard
> bindings:
>
> - The standard bindings state that a pinctrl node must contain either a "pins"
>   property or a "groups" property, while the Renesas bindings allows for both
>   to coexist in the same node.

Sascha also says this makes sense for him so I guess I'm getting a bit
soft on the issue.

> - The standard bindings don't allow a pinmux node to contain a "pins" property,
>   while the Renesas bindings do.

Does that mean "pins" affect the muxing or that "pins" is about some per-pin
config shoveled into the same node?

The former is not OK, the latter is.

>                 mmcif_pins: mmcif {
>                         mux {
> -                               renesas,groups = "mmc0_data8_0", "mmc0_ctrl_0";
> -                               renesas,function = "mmc0";
> +                               groups = "mmc0_data8_0", "mmc0_ctrl_0";
> +                               function = "mmc0";
>                         };

So that looks just very nice.

>                         cfg {
> -                               renesas,groups = "mmc0_data8_0";
> -                               renesas,pins = "PORT279";
> +                               groups = "mmc0_data8_0";
> +                               pins = "PORT279";
>                                 bias-pull-up;

And here I can't see the use of "groups" in this node since it
doesn't match a function. It's a bit ambiguous what "groups"
mean when you run into it like this.

Yours,
Linus Walleij
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