drivers: gpio: stm32: do not resume device when flag is DISCONNECTED

Fix a bug where after a standby, it was impossible to reenable a GPIO
clock.

A counter is incremented each time pm_device_runtime_get is called, and
decremented each time pm_device_runtime_put is called. The
clock is only enabled if this counter equals 1.
When configuring a GPIO (as input or output), the timer is incremented, and
when disconnecting it, it is both incremented and decremented. Thus the
next time we try to configuring it, the clock is not enabled (since the
counter will now be equal to 2).

This causes a problem when using low power standby mode: after wakeup all
clocks are disabled and the GPIO clock can not be reenabled.

This commit fixes this bug by not incrementing the counter when disconnect
is asked (or in other words incrementing it only when configuring either
an input or an output).

Signed-off-by: Guillaume Gautier <[email protected]>

Author: gautierg-st

drivers/gpio/gpio_stm32.c

@@ -524,9 +524,11 @@ static int gpio_stm32_config(const struct device *dev,
 	}
 
 	/* Enable device clock before configuration (requires bank writes) */
-	err = pm_device_runtime_get(dev);
-	if (err < 0) {
-		return err;
+	if (((flags & GPIO_OUTPUT) != 0) || ((flags & GPIO_INPUT) != 0)) {
+		err = pm_device_runtime_get(dev);
+		if (err < 0) {
+			return err;
+		}
 	}
 
 	if ((flags & GPIO_OUTPUT) != 0) {