linux-kernel - Re: [PATCH 2/2] USB: serial: cp210x: use new GPIO line value setter callbacks

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Message-ID: <aFLQ_G0HnGWVSE12@hovoldconsulting.com>
Date: Wed, 18 Jun 2025 16:45:16 +0200
From: Johan Hovold <johan@...nel.org>
To: Bartosz Golaszewski <brgl@...ev.pl>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Linus Walleij <linus.walleij@...aro.org>, linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-gpio@...r.kernel.org,
	Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH 2/2] USB: serial: cp210x: use new GPIO line value setter
 callbacks

On Tue, Jun 10, 2025 at 02:43:47PM +0200, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> 
> struct gpio_chip now has callbacks for setting line values that return
> an integer, allowing to indicate failures. Convert the driver to using
> them.
> 
> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> ---
>  drivers/usb/serial/cp210x.c | 18 +++++++-----------
>  1 file changed, 7 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/usb/serial/cp210x.c b/drivers/usb/serial/cp210x.c
> index 9960ac2b10b719192dfbab0a6e81b2cf80f40d36..caeb2873a60451fb7a9a5b5d25071547b5401d52 100644
> --- a/drivers/usb/serial/cp210x.c
> +++ b/drivers/usb/serial/cp210x.c
> @@ -1504,7 +1504,7 @@ static int cp210x_gpio_get(struct gpio_chip *gc, unsigned int gpio)
>  	return !!(mask & BIT(gpio));
>  }
>  
> -static void cp210x_gpio_set(struct gpio_chip *gc, unsigned int gpio, int value)
> +static int cp210x_gpio_set(struct gpio_chip *gc, unsigned int gpio, int value)
>  {
>  	struct usb_serial *serial = gpiochip_get_data(gc);
>  	struct cp210x_serial_private *priv = usb_get_serial_data(serial);
> @@ -1522,8 +1522,8 @@ static void cp210x_gpio_set(struct gpio_chip *gc, unsigned int gpio, int value)
>  	mask = BIT(gpio);
>  
>  	result = usb_autopm_get_interface(serial->interface);
> -	if (result)
> -		goto out;
> +	if (result < 0)
> +		return result;

This is arguably an unrelated change, please keep it as is.

>  	switch (priv->partnum) {
>  	case CP210X_PARTNUM_CP2105:
> @@ -1555,11 +1555,8 @@ static void cp210x_gpio_set(struct gpio_chip *gc, unsigned int gpio, int value)
>  	}
>  
>  	usb_autopm_put_interface(serial->interface);
> -out:
> -	if (result < 0) {
> -		dev_err(&serial->interface->dev, "failed to set GPIO value: %d\n",
> -				result);
> -	}

And keep this in place too, and just result if negative.

> +
> +	return result < 0 ? result : 0;

And return 0 explicitly here to avoid using the ternary operator.

>  }

Johan