linux-kernel - Re: [PATCH v1 2/2] usb: typec: mux: gpio-sbu: Make enable gpio optional

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Date: Fri, 24 May 2024 12:56:15 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Francesco Dolcini <francesco@...cini.it>
Cc: Heikki Krogerus <heikki.krogerus@...ux.intel.com>, 
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Francesco Dolcini <francesco.dolcini@...adex.com>, 
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Bjorn Andersson <andersson@...nel.org>
Subject: Re: [PATCH v1 2/2] usb: typec: mux: gpio-sbu: Make enable gpio
 optional

On Fri, May 24, 2024 at 09:10:34AM +0200, Francesco Dolcini wrote:
> From: Francesco Dolcini <francesco.dolcini@...adex.com>
> 
> The enable gpio is not required when the SBU mux is used only for
> orientation, make it optional.
> 
> Signed-off-by: Francesco Dolcini <francesco.dolcini@...adex.com>
> ---
>  drivers/usb/typec/mux/gpio-sbu-mux.c | 11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/usb/typec/mux/gpio-sbu-mux.c b/drivers/usb/typec/mux/gpio-sbu-mux.c
> index 374168482d36..cf44259980a1 100644
> --- a/drivers/usb/typec/mux/gpio-sbu-mux.c
> +++ b/drivers/usb/typec/mux/gpio-sbu-mux.c
> @@ -47,7 +47,7 @@ static int gpio_sbu_switch_set(struct typec_switch_dev *sw,
>  		break;
>  	}
>  
> -	if (enabled != sbu_mux->enabled)
> +	if (sbu_mux->enable_gpio && enabled != sbu_mux->enabled)
>  		gpiod_set_value_cansleep(sbu_mux->enable_gpio, enabled);

I think it's safe to pass NULL to gpiod_set_value_cansleep().

>  
>  	if (swapped != sbu_mux->swapped)
> @@ -66,6 +66,9 @@ static int gpio_sbu_mux_set(struct typec_mux_dev *mux,
>  {
>  	struct gpio_sbu_mux *sbu_mux = typec_mux_get_drvdata(mux);
>  
> +	if (!sbu_mux->enable_gpio)
> +		return -EOPNOTSUPP;

Can we skip registering the mux if there is no enable_gpio? This can
save users from the unexpected errors during runtime.

> +
>  	mutex_lock(&sbu_mux->lock);
>  
>  	switch (state->mode) {
> @@ -102,7 +105,8 @@ static int gpio_sbu_mux_probe(struct platform_device *pdev)
>  
>  	mutex_init(&sbu_mux->lock);
>  
> -	sbu_mux->enable_gpio = devm_gpiod_get(dev, "enable", GPIOD_OUT_LOW);
> +	sbu_mux->enable_gpio = devm_gpiod_get_optional(dev, "enable",
> +						       GPIOD_OUT_LOW);
>  	if (IS_ERR(sbu_mux->enable_gpio))
>  		return dev_err_probe(dev, PTR_ERR(sbu_mux->enable_gpio),
>  				     "unable to acquire enable gpio\n");
> @@ -141,7 +145,8 @@ static void gpio_sbu_mux_remove(struct platform_device *pdev)
>  {
>  	struct gpio_sbu_mux *sbu_mux = platform_get_drvdata(pdev);
>  
> -	gpiod_set_value_cansleep(sbu_mux->enable_gpio, 0);
> +	if (sbu_mux->enable_gpio)
> +		gpiod_set_value_cansleep(sbu_mux->enable_gpio, 0);
>  
>  	typec_mux_unregister(sbu_mux->mux);
>  	typec_switch_unregister(sbu_mux->sw);
> -- 
> 2.39.2
> 

-- 
With best wishes
Dmitry