linux-kernel - Re: [PATCH v3 3/4] Input: Don't program hw debounce for soc_button

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Message-ID: <61843beb-263d-475b-9876-fb273dd8d7fe@kernel.org>
Date: Thu, 26 Jun 2025 10:27:01 +0200
From: Hans de Goede <hansg@...nel.org>
To: Mario Limonciello <superm1@...nel.org>,
 Mika Westerberg <westeri@...nel.org>,
 Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
 Linus Walleij <linus.walleij@...aro.org>, Bartosz Golaszewski
 <brgl@...ev.pl>, Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc: "open list:GPIO ACPI SUPPORT" <linux-gpio@...r.kernel.org>,
 "open list:GPIO ACPI SUPPORT" <linux-acpi@...r.kernel.org>,
 open list <linux-kernel@...r.kernel.org>,
 "open list:INPUT (KEYBOARD, MOUSE, JOYSTICK, TOUCHSCREEN)..."
 <linux-input@...r.kernel.org>, Mario Limonciello <mario.limonciello@....com>
Subject: Re: [PATCH v3 3/4] Input: Don't program hw debounce for
 soc_button_array devices

Hi,

On 25-Jun-25 23:58, Mario Limonciello wrote:
> From: Mario Limonciello <mario.limonciello@....com>
> 
> Programming a hardware debounce of 50ms causes problems where a button
> doesn't work properly anymore on some systems.  This debounce is intended
> for compatibility with systems with a mechanical switch so soc_button_array
> devices should only be using a sofware debounce.
> 
> Add support for indicating that a driver is only requesting gpio_keys
> to use software debounce support and mark that in soc_button_array
> accordingly.
> 
> Suggested-by: Hans de Goede <hansg@...nel.org>
> Fixes: 5c4fa2a6da7fb ("Input: soc_button_array - debounce the buttons")
> Signed-off-by: Mario Limonciello <mario.limonciello@....com>

Thanks, patch looks good to me:

Reviewed-by: Hans de Goede <hansg@...nel.org>

Regards,

Hans



> ---
>  drivers/input/keyboard/gpio_keys.c    | 7 +++++--
>  drivers/input/misc/soc_button_array.c | 1 +
>  include/linux/gpio_keys.h             | 2 ++
>  3 files changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/input/keyboard/gpio_keys.c b/drivers/input/keyboard/gpio_keys.c
> index f9db86da0818b..773aa5294d269 100644
> --- a/drivers/input/keyboard/gpio_keys.c
> +++ b/drivers/input/keyboard/gpio_keys.c
> @@ -552,8 +552,11 @@ static int gpio_keys_setup_key(struct platform_device *pdev,
>  		bool active_low = gpiod_is_active_low(bdata->gpiod);
>  
>  		if (button->debounce_interval) {
> -			error = gpiod_set_debounce(bdata->gpiod,
> -					button->debounce_interval * 1000);
> +			if (ddata->pdata->no_hw_debounce)
> +				error = -EINVAL;
> +			else
> +				error = gpiod_set_debounce(bdata->gpiod,
> +							   button->debounce_interval * 1000);
>  			/* use timer if gpiolib doesn't provide debounce */
>  			if (error < 0)
>  				bdata->software_debounce =
> diff --git a/drivers/input/misc/soc_button_array.c b/drivers/input/misc/soc_button_array.c
> index b8cad415c62ca..dac940455bea8 100644
> --- a/drivers/input/misc/soc_button_array.c
> +++ b/drivers/input/misc/soc_button_array.c
> @@ -232,6 +232,7 @@ soc_button_device_create(struct platform_device *pdev,
>  	gpio_keys_pdata->buttons = gpio_keys;
>  	gpio_keys_pdata->nbuttons = n_buttons;
>  	gpio_keys_pdata->rep = autorepeat;
> +	gpio_keys_pdata->no_hw_debounce = TRUE;
>  
>  	pd = platform_device_register_resndata(&pdev->dev, "gpio-keys",
>  					       PLATFORM_DEVID_AUTO, NULL, 0,
> diff --git a/include/linux/gpio_keys.h b/include/linux/gpio_keys.h
> index 80fa930b04c67..c99f74467fda6 100644
> --- a/include/linux/gpio_keys.h
> +++ b/include/linux/gpio_keys.h
> @@ -48,6 +48,7 @@ struct gpio_keys_button {
>   * @enable:		platform hook for enabling the device
>   * @disable:		platform hook for disabling the device
>   * @name:		input device name
> + * @no_hw_debounce:	avoid programming hardware debounce
>   */
>  struct gpio_keys_platform_data {
>  	const struct gpio_keys_button *buttons;
> @@ -57,6 +58,7 @@ struct gpio_keys_platform_data {
>  	int (*enable)(struct device *dev);
>  	void (*disable)(struct device *dev);
>  	const char *name;
> +	bool no_hw_debounce;
>  };
>  
>  #endif