linux-kernel - Re: [PATCH] pinctrl: reserve pins when states are activated

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Date:	Fri, 19 Oct 2012 14:51:21 +0200
From:	Linus Walleij <linus.walleij@...aro.org>
To:	Stephen Warren <swarren@...dotorg.org>
Cc:	Linus Walleij <linus.walleij@...ricsson.com>,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	Stephen Warren <swarren@...dia.com>,
	Anmar Oueja <anmar.oueja@...aro.org>,
	Patrice Chotard <patrice.chotard@...com>,
	Jean Nicolas Graux <jean-nicolas.graux@...ricsson.com>,
	Loic Pallardy <loic.pallardy@...com>
Subject: Re: [PATCH] pinctrl: reserve pins when states are activated

On Fri, Oct 19, 2012 at 1:33 AM, Stephen Warren <swarren@...dotorg.org> wrote:
> On 10/18/2012 04:01 AM, Linus Walleij wrote:
>> This switches the way that pins are reserved for multiplexing:
>
> The conceptual change makes perfect sense to me.

Thanks...

>> diff --git a/drivers/pinctrl/pinmux.c b/drivers/pinctrl/pinmux.c
>
>>  void pinmux_free_setting(struct pinctrl_setting const *setting)
> ...
>> +     /*
>> +      * If a setting is active, disable it so that all pins are released
>> +      */
>> +     pinmux_disable_setting(setting);
>
> "*If* a setting is active ..." implies there should be a C if statement
> here to check if the setting is actually active before trying to disable it?

Spot on.

Actually in core.c we're already checking this:

	case PIN_MAP_TYPE_MUX_GROUP:
		if (state == p->state)
			pinmux_disable_setting(setting);
		pinmux_free_setting(setting);
		break;

So this is just buggy driving the refcount down to negative.
(I think Jean-Nicolas noticed this phenomenon...)

I should just delete pinmux_free_setting().

Yours,
Linus Walleij

Yours,
Linus Walleij
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