[PATCH] input: gpio-keys: initialize the input value with the current gpioval

[PATCH] input: gpio-keys: initialize the input value with the current gpioval

[Sascha Hauer]

This is required for deep-probe systems which probe the "gpio-keys"
device on demand. In such case the input value is not yet accessible
once the probe finished because the first gpio reads happen
asynchronously to the probe function. However, board code queries the
input device value directly after the of.*ensure.*probed().

Therefore provide a sane default by reading the gpio value during probe
and init the input device value.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
 drivers/input/gpio_keys.c | 31 +++++++++++++++++++++----------
 1 file changed, 21 insertions(+), 10 deletions(-)

diff --git a/drivers/input/gpio_keys.c b/drivers/input/gpio_keys.c
index b52738f5cc..0fb09007a9 100644
--- a/drivers/input/gpio_keys.c
+++ b/drivers/input/gpio_keys.c
@@ -30,25 +30,18 @@ struct gpio_keys {
 	struct input_device input;
 };
 
-static void gpio_key_poller(void *data)
+static void gpio_keys_read(struct gpio_keys *gk, bool force)
 {
-	struct gpio_keys *gk = data;
 	struct gpio_key *gb;
 	int i, pressed;
 
-	for (i = 0; i < gk->nbuttons; i++) {
-		gb = &gk->buttons[i];
-
-		if (gpiod_slice_acquired(gb->gpio))
-			goto out;
-	}
-
 	for (i = 0; i < gk->nbuttons; i++) {
 
 		gb = &gk->buttons[i];
 		pressed = gpiod_get_value(gb->gpio);
 
-		if (!is_timeout(gb->debounce_start, gb->debounce_interval * MSECOND))
+		if (!force && !is_timeout(gb->debounce_start,
+					  gb->debounce_interval * MSECOND))
 			continue;
 
 		if (pressed != gb->previous_state) {
@@ -59,6 +52,22 @@ static void gpio_key_poller(void *data)
 			gb->previous_state = pressed;
 		}
 	}
+}
+
+static void gpio_key_poller(void *data)
+{
+	struct gpio_keys *gk = data;
+	struct gpio_key *gb;
+	int i;
+
+	for (i = 0; i < gk->nbuttons; i++) {
+		gb = &gk->buttons[i];
+
+		if (gpiod_slice_acquired(gb->gpio))
+			goto out;
+	}
+
+	gpio_keys_read(gk, false);
 out:
 	poller_call_async(&gk->poller, 10 * MSECOND, gpio_key_poller, gk);
 }
@@ -167,6 +176,8 @@ static int __init gpio_keys_probe(struct device *dev)
 	if (ret)
 		return ret;
 
+	gpio_keys_read(gk, true);
+
 	poller_call_async(&gk->poller, 10 * MSECOND, gpio_key_poller, gk);
 
 	return 0;
-- 
2.47.3

Re: [PATCH] input: gpio-keys: initialize the input value with the current gpioval

[Sascha Hauer]

Hi Marco,

I just sent an alternative patch which avoids some code duplication.
It's untested, maybe you could spin a test for your case.

Sascha

On 2026-06-25 13:51, Marco Felsch wrote:
> This is required for deep-probe systems which prove the "gpio-keys"
> device on demand. In such case the input value is not yet accessible
> once the probe finished. However, board code queries the input device
> value directly after the of.*ensure.*probed().
> 
> Therefore provide a sane default by reading the gpio value during probe
> and init the input device value.
> 
> Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
> ---
>  drivers/input/gpio_keys.c | 22 ++++++++++++++++++++++
>  1 file changed, 22 insertions(+)
> 
> diff --git a/drivers/input/gpio_keys.c b/drivers/input/gpio_keys.c
> index b52738f5ccb2..316ed73ddfd1 100644
> --- a/drivers/input/gpio_keys.c
> +++ b/drivers/input/gpio_keys.c
> @@ -143,6 +143,26 @@ static int gpio_keys_probe_dt(struct gpio_keys *gk, struct device *dev)
>  	return 0;
>  }
>  
> +static int gpio_keys_set_initialval(struct gpio_keys *gk)
> +{
> +	struct gpio_key *gb;
> +	int i, pressed;
> +
> +	for (i = 0; i < gk->nbuttons; i++) {
> +
> +		gb = &gk->buttons[i];
> +		pressed = gpiod_get_value(gb->gpio);
> +
> +		if (pressed != gb->previous_state) {
> +			gb->debounce_start = get_time_ns();
> +			input_report_key_event(&gk->input, gb->code, pressed);
> +			dev_dbg(gk->input.parent, "%s gpio #%d as %d\n",
> +				pressed ? "pressed" : "released", i, gb->code);
> +			gb->previous_state = pressed;
> +		}
> +	}
> +}
> +
>  static int __init gpio_keys_probe(struct device *dev)
>  {
>  	int ret;
> @@ -163,6 +183,8 @@ static int __init gpio_keys_probe(struct device *dev)
>  	if (ret)
>  		return ret;
>  
> +	gpio_keys_set_initialval(gk);
> +
>  	ret = poller_async_register(&gk->poller, dev_name(dev));
>  	if (ret)
>  		return ret;
> -- 
> 2.47.3
> 
> 
> 

-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

[PATCH] input: gpio-keys: initialize the input value with the current gpioval

[Marco Felsch]

This is required for deep-probe systems which prove the "gpio-keys"
device on demand. In such case the input value is not yet accessible
once the probe finished. However, board code queries the input device
value directly after the of.*ensure.*probed().

Therefore provide a sane default by reading the gpio value during probe
and init the input device value.

Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
---
 drivers/input/gpio_keys.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/drivers/input/gpio_keys.c b/drivers/input/gpio_keys.c
index b52738f5ccb2..316ed73ddfd1 100644
--- a/drivers/input/gpio_keys.c
+++ b/drivers/input/gpio_keys.c
@@ -143,6 +143,26 @@ static int gpio_keys_probe_dt(struct gpio_keys *gk, struct device *dev)
 	return 0;
 }
 
+static int gpio_keys_set_initialval(struct gpio_keys *gk)
+{
+	struct gpio_key *gb;
+	int i, pressed;
+
+	for (i = 0; i < gk->nbuttons; i++) {
+
+		gb = &gk->buttons[i];
+		pressed = gpiod_get_value(gb->gpio);
+
+		if (pressed != gb->previous_state) {
+			gb->debounce_start = get_time_ns();
+			input_report_key_event(&gk->input, gb->code, pressed);
+			dev_dbg(gk->input.parent, "%s gpio #%d as %d\n",
+				pressed ? "pressed" : "released", i, gb->code);
+			gb->previous_state = pressed;
+		}
+	}
+}
+
 static int __init gpio_keys_probe(struct device *dev)
 {
 	int ret;
@@ -163,6 +183,8 @@ static int __init gpio_keys_probe(struct device *dev)
 	if (ret)
 		return ret;
 
+	gpio_keys_set_initialval(gk);
+
 	ret = poller_async_register(&gk->poller, dev_name(dev));
 	if (ret)
 		return ret;
-- 
2.47.3