linux-kernel - Re: [PATCH] pinctrl: sunxi: set pin function as input on export

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Message-ID: <CACRpkdbd4f3yj2MnR6PU5SuhV5Tj4HzWLc0UX8jQkcJp7MoTig@mail.gmail.com>
Date:	Mon, 15 Feb 2016 23:04:26 +0100
From:	Linus Walleij <linus.walleij@...aro.org>
To:	Krzysztof Adamski <krzysztof.adamski@...to.com>
Cc:	Maxime Ripard <maxime.ripard@...e-electrons.com>,
	Chen-Yu Tsai <wens@...e.org>,
	Hans de Goede <hdegoede@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Lee Jones <lee.jones@...aro.org>,
	Jonas Gorski <jogo@...nwrt.org>,
	"linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linux-sunxi <linux-sunxi@...glegroups.com>
Subject: Re: [PATCH] pinctrl: sunxi: set pin function as input on export

On Mon, Feb 8, 2016 at 3:37 PM, Krzysztof Adamski
<krzysztof.adamski@...to.com> wrote:

> Default function of a pin in sunxi SoCs is "disabled". By default gpios
> exported by sysfs are set as input and indeed, when reading "direction"
> file you will get "in". The "value" pin won't return proper value,
> though, confusing user of this interface.
>
> This patch sets direction of a GPIO as input when exporting it.
>
> Signed-off-by: Krzysztof Adamski <krzysztof.adamski@...to.com>

As maxime says it's not a sunxi problem.

So maybe it is wrong to set pins to either input or output when
exporting them, I suspect they should be exported as is.

Also: the sysfs ABI is deprecated. I suggest you invest your time
in working on the new chardev ABI.

Yours,
Linus Walleij