linux-kernel - Re: [PATCH v2 2/2] reset: Add GPIO support to reset controller framework

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Date:	Tue, 07 Jan 2014 12:28:09 +0100
From:	Philipp Zabel <p.zabel@...gutronix.de>
To:	Maxime Ripard <maxime.ripard@...e-electrons.com>
Cc:	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	kernel@...gutronix.de, Roger Quadros <rogerq@...com>,
	Mark Rutland <mark.rutland@....com>,
	Stephen Warren <swarren@...dotorg.org>,
	Alexandre Courbot <gnurou@...il.com>
Subject: Re: [PATCH v2 2/2] reset: Add GPIO support to reset controller
 framework

Am Dienstag, den 07.01.2014, 12:19 +0100 schrieb Maxime Ripard:
> Hi Philipp,
> 
> On Tue, Jan 07, 2014 at 10:52:21AM +0100, Philipp Zabel wrote:
> > > > +	const char *gpio_con_id = "reset";
> > > > +	struct reset_controller_dev *rcdev;
> > > > +	struct reset_control *rstc;
> > > > +	struct gpio_desc *gpiod;
> > > > +	bool asserted = false;
> > > > +	char scratch[48];
> > > > +	int ret;
> > > > +
> > > > +	if (id) {
> > > > +		snprintf(scratch, 48, "%s-reset-boot-asserted", id);
> > > > +		assert_prop = scratch;
> > > > +	}
> > > > +
> > > > +	asserted = of_property_read_bool(dev->of_node, assert_prop);
> > > > +
> > > > +	if (id) {
> > > > +		snprintf(scratch, 48, "%s-reset", id);
> > > > +		gpio_con_id = scratch;
> > > > +	}
> > > > +
> > > > +	gpiod = gpiod_get(dev, gpio_con_id);
> > > > +	if (IS_ERR(gpiod)) {
> > > > +		dev_err(dev, "Failed to get GPIO reset: %ld\n", PTR_ERR(gpiod));
> > > > +		return ERR_CAST(gpiod);
> > > > +	}
> > > > +
> > > > +	ret = gpiod_direction_output(gpiod, asserted);
> > > > +	if (ret < 0)
> > > > +		goto err_put;
> > > 
> > > What happens if the GPIO is active low? I see no way in your binding
> > > and driver to give that information, and that would change the
> > > behaviour quite a bit.
> > 
> > I was under the (wrong) impression that gpiod_direction_output takes a
> > logical value as gpiod_set_value does. Will fix that.
> 
> I don't think gpiod_set_value does either unfortunately.

It does, and Alexandre (added to Cc:) suggested that
gpiod_direction_output probably should, too.
I'll send a patch.

regards
Philipp

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