linux-kernel - Re: [PATCH 4/6] regulator: lp872x: Add enable GPIO pin support

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Date:	Thu, 24 Dec 2015 19:12:53 +0100
From:	Paul Kocialkowski <contact@...lk.fr>
To:	Mark Brown <broonie@...nel.org>
Cc:	linux-kernel@...r.kernel.org, Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Russell King <linux@....linux.org.uk>,
	Benoît Cousson <bcousson@...libre.com>,
	Tony Lindgren <tony@...mide.com>,
	Liam Girdwood <lgirdwood@...il.com>,
	Milo Kim <milo.kim@...com>, devicetree@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-omap@...r.kernel.org
Subject: Re: [PATCH 4/6] regulator: lp872x: Add enable GPIO pin support

Le mercredi 23 décembre 2015 à 11:56 +0000, Mark Brown a écrit :
> On Wed, Dec 23, 2015 at 11:58:37AM +0100, Paul Kocialkowski wrote:
> 
> > +	gpio = lp->pdata->enable_gpio;
> > +	if (!gpio_is_valid(gpio))
> > +		return 0;
> > +
> > +	/* Always set enable GPIO high. */
> > +	ret = devm_gpio_request_one(lp->dev, gpio, GPIOF_OUT_INIT_HIGH, "LP872X EN");
> > +	if (ret) {
> > +		dev_err(lp->dev, "gpio request err: %d\n", ret);
> > +		return ret;
> > +	}
> 
> This isn't really adding support for the enable GPIO as the changelog
> suggests, it's requesting but not managing the GPIO.  Since there is
> core support for manging enable GPIOs this seems especially silly,
> please tell the core about the GPIO and then it will work at runtime
> too.

It looks like the core bindings for GPIO can only be used instead of the
rdev->desc->ops->enable callback, not jointly, which doesn't fit my use
case, where both the GPIO and register write have to be used to enable
regulators.

I think it would be worth making it possible to use both in core, since
that situation is probably shared with other regulators. I suggest the
following diff (that would be split into a separate patch in v2 of this
series):

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index e92f344..dd0674f 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -1963,7 +1963,6 @@ static int regulator_ena_gpio_ctrl(struct
regulator_dev *rdev, bool enable)
 		if (pin->enable_count == 0)
 			gpiod_set_value_cansleep(pin->gpiod,
 						 !pin->ena_gpio_invert);
-
 		pin->enable_count++;
 	} else {
 		if (pin->enable_count > 1) {
@@ -2063,6 +2062,14 @@ static int _regulator_do_enable(struct
regulator_dev *rdev)
 		}
 	}
 
+	if (rdev->desc->ops->enable) {
+		ret = rdev->desc->ops->enable(rdev);
+		if (ret < 0)
+			return ret;
+	} else if (!rdev->ena_pin) {
+		return -EINVAL;
+	}
+
 	if (rdev->ena_pin) {
 		if (!rdev->ena_gpio_state) {
 			ret = regulator_ena_gpio_ctrl(rdev, true);
@@ -2070,10 +2077,6 @@ static int _regulator_do_enable(struct
regulator_dev *rdev)
 				return ret;
 			rdev->ena_gpio_state = 1;
 		}
-	} else if (rdev->desc->ops->enable) {
-		ret = rdev->desc->ops->enable(rdev);
-		if (ret < 0)
-			return ret;
 	} else {
 		return -EINVAL;
 	}

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