linux-kernel - Re: [PATCH 06/13 v2] regulator: max8973: Let core handle GPIO descriptor

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Date:   Wed, 5 Dec 2018 13:08:26 +0000
From:   Charles Keepax <ckeepax@...nsource.cirrus.com>
To:     Linus Walleij <linus.walleij@...aro.org>
CC:     Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        <linux-kernel@...r.kernel.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Marek Szyprowski <m.szyprowski@...sung.com>
Subject: Re: [PATCH 06/13 v2] regulator: max8973: Let core handle GPIO
 descriptor

On Sat, Dec 01, 2018 at 04:41:44PM +0100, Linus Walleij wrote:
> Use the gpiod_get() rather than the devm_* version so that the
> regulator core can handle the lifecycle of these descriptors.
> 
> Fixes: e7d2be696faa ("regulator: max8973: Pass descriptor instead of GPIO number")
> Signed-off-by: Linus Walleij <linus.walleij@...aro.org>
> ---
> ChangeLog v1->v2:
> - Drop the gpiod_put() on the errorpath after devm_regulator_register()
>   as this will be handled by the regulator core.
> - Fix the second case of devm_gpiod_get()
> - Put a comment in the code so maintainers knows not to
>   use managed resources (devm*)
> ---
> @@ -759,9 +759,13 @@ static int max8973_probe(struct i2c_client *client,
>  		else
>  			gflags = GPIOD_OUT_LOW;
>  		gflags |= GPIOD_FLAGS_BIT_NONEXCLUSIVE;
> -		gpiod = devm_gpiod_get_optional(&client->dev,
> -						"maxim,enable",
> -						gflags);
> +		/*
> +		 * Do not use devm* here: the regulator core takes over the
> +		 * lifecycle management of the GPIO descriptor.
> +		 */
> +		gpiod = gpiod_get_optional(&client->dev,
> +					   "maxim,enable",
> +					   gflags);
>  		if (IS_ERR(gpiod))
>  			return PTR_ERR(gpiod);
>  		if (gpiod) {
> @@ -775,10 +779,13 @@ static int max8973_probe(struct i2c_client *client,
>  		/*
>  		 * We do not let the core switch this regulator on/off,
>  		 * we just leave it on.
> +		 *
> +		 * Do not use devm* here: the regulator core takes over the
> +		 * lifecycle management of the GPIO descriptor.
>  		 */
> -		gpiod = devm_gpiod_get_optional(&client->dev,
> -						"maxim,enable",
> -						GPIOD_OUT_HIGH);
> +		gpiod = gpiod_get_optional(&client->dev,
> +					   "maxim,enable",
> +					   GPIOD_OUT_HIGH);

Need to be careful here this path actually never passes the GPIO
to the regulator core. I suspect you want to leave this one as a
devm_

>  		if (IS_ERR(gpiod))
>  			return PTR_ERR(gpiod);
>  		if (gpiod)
> @@ -798,6 +805,8 @@ static int max8973_probe(struct i2c_client *client,
>  
>  	ret = max8973_init_dcdc(max, pdata);
>  	if (ret < 0) {
> +		if (gpiod)
> +			gpiod_put(gpiod);

And make this use config.ena_gpiod instead.

Thanks,
Charles