drivers: serial: uart_nrfx_uarte: Avoid incorrect UARTE disable when using runtime PM

When CONFIG_PM_DEVICE_RUNTIME is enabled, the code can incorrectly call
nrf_uarte_disable() after TXSTOPPED, even though runtime power management is
supposed to handle disabling the UARTE.

This happens if the UARTE_FLAG_POLL_OUT flag is not set — in that case,
the call to pm_device_runtime_put() is skipped, and nrf_uarte_disable() is
called directly instead, which isn't correct when runtime PM is active.

This fix prevents nrf_uarte_disable() from being called in this scenario,
so that the UARTE is only disabled by the PM system when appropriate.

Signed-off-by: Vivek Sahi <[email protected]>

Author: viveksahi1

drivers/serial/uart_nrfx_uarte.c

@@ -353,10 +353,11 @@ static void uarte_nrfx_isr_int(const void *arg)
 	if (txstopped && (IS_ENABLED(CONFIG_PM_DEVICE_RUNTIME) || LOW_POWER_ENABLED(config))) {
 		unsigned int key = irq_lock();
 
-		if (IS_ENABLED(CONFIG_PM_DEVICE_RUNTIME) &&
-		    (data->flags & UARTE_FLAG_POLL_OUT)) {
-			data->flags &= ~UARTE_FLAG_POLL_OUT;
-			pm_device_runtime_put(dev);
+		if (IS_ENABLED(CONFIG_PM_DEVICE_RUNTIME)) {
+			if (data->flags & UARTE_FLAG_POLL_OUT) {
+				data->flags &= ~UARTE_FLAG_POLL_OUT;
+				pm_device_runtime_put(dev);
+			}
 		} else {
 			nrf_uarte_disable(uarte);
 		}