linux-kernel - Re: [PATCH v4 2/4] input: gpio-vibra: Allow to use vcc-supply alone to control the vibrator

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Date:   Wed, 29 Jul 2020 23:19:39 -0700
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Ondrej Jirman <megous@...ous.com>
Cc:     linux-sunxi@...glegroups.com, Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Maxime Ripard <mripard@...nel.org>,
        Chen-Yu Tsai <wens@...e.org>, Luca Weiss <luca@...tu.xyz>,
        Tomas Novotny <tomas@...otny.cz>, linux-input@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v4 2/4] input: gpio-vibra: Allow to use vcc-supply alone
 to control the vibrator

Hi Ondrej,

On Tue, Jul 14, 2020 at 12:23:01PM +0200, Ondrej Jirman wrote:
> Make enable-gpio optional to allow using this driver with boards that
> have vibrator connected to a power supply without intermediate gpio
> based enable circuitry.
> 
> Also avoid a case where neither regulator nor enable gpio is specified,
> and bail out in probe in such a case.
> 
> Signed-off-by: Ondrej Jirman <megous@...ous.com>
> ---
>  drivers/input/misc/gpio-vibra.c | 14 ++++++++++----
>  1 file changed, 10 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/input/misc/gpio-vibra.c b/drivers/input/misc/gpio-vibra.c
> index f79f75595dd7..b3bb7e61ed1d 100644
> --- a/drivers/input/misc/gpio-vibra.c
> +++ b/drivers/input/misc/gpio-vibra.c
> @@ -39,7 +39,7 @@ static int gpio_vibrator_start(struct gpio_vibrator *vibrator)
>  	struct device *pdev = vibrator->input->dev.parent;
>  	int err;
>  
> -	if (!vibrator->vcc_on) {
> +	if (vibrator->vcc && !vibrator->vcc_on) {
>  		err = regulator_enable(vibrator->vcc);
>  		if (err) {
>  			dev_err(pdev, "failed to enable regulator: %d\n", err);
> @@ -57,7 +57,7 @@ static void gpio_vibrator_stop(struct gpio_vibrator *vibrator)
>  {
>  	gpiod_set_value_cansleep(vibrator->gpio, 0);
>  
> -	if (vibrator->vcc_on) {
> +	if (vibrator->vcc && vibrator->vcc_on) {
>  		regulator_disable(vibrator->vcc);
>  		vibrator->vcc_on = false;
>  	}
> @@ -112,7 +112,7 @@ static int gpio_vibrator_probe(struct platform_device *pdev)
>  	if (!vibrator->input)
>  		return -ENOMEM;
>  
> -	vibrator->vcc = devm_regulator_get(&pdev->dev, "vcc");
> +	vibrator->vcc = devm_regulator_get_optional(&pdev->dev, "vcc");

I know it is very surprising, but regulator_get_optional does not return
NULL when regulator is not present, but rather ERR_PTR(-ENODEV). You
need to replace it with NULL in the branch below, or change conditions
to !IS_ERR(virbrator->vcc) (and still handle -ENODEV in the branch
below).

>  	err = PTR_ERR_OR_ZERO(vibrator->vcc);
>  	if (err) {
>  		if (err != -EPROBE_DEFER)
> @@ -121,7 +121,8 @@ static int gpio_vibrator_probe(struct platform_device *pdev)
>  		return err;
>  	}
>  
> -	vibrator->gpio = devm_gpiod_get(&pdev->dev, "enable", GPIOD_OUT_LOW);
> +	vibrator->gpio = devm_gpiod_get_optional(&pdev->dev, "enable",
> +						 GPIOD_OUT_LOW);
>  	err = PTR_ERR_OR_ZERO(vibrator->gpio);
>  	if (err) {
>  		if (err != -EPROBE_DEFER)
> @@ -130,6 +131,11 @@ static int gpio_vibrator_probe(struct platform_device *pdev)
>  		return err;
>  	}
>  
> +	if (!vibrator->vcc && !vibrator->gpio) {
> +		dev_err(&pdev->dev, "Neither gpio nor regulator provided\n");
> +		return -EINVAL;
> +	}
> +
>  	INIT_WORK(&vibrator->play_work, gpio_vibrator_play_work);
>  
>  	vibrator->input->name = "gpio-vibrator";
> -- 
> 2.27.0
> 

Thanks.

-- 
Dmitry