applications: nrf_desktop: Align behavior on USB disconnection

Adds power manager restriction and forces power down on USB
disconnected event for consistency as it can also be done on
disconnection by USB suspended event. Adds option to delay
system off after USB disconnection by few seconds to allow
user to take actions like restart advertising without going
through reboot.

Jira: NCSDK-17701

Signed-off-by: Aleksander Strzebonski <[email protected]>

Author: alstrzebonski

applications/nrf_desktop/src/modules/Kconfig.usb_state

@@ -57,6 +57,21 @@ config DESKTOP_USB_PM_REQ_NO_PM_LATENCY
 	  latency and ensures high performance. While USB is active, application
 	  power down is blocked anyway.
 
+config DESKTOP_USB_PM_RESTRICT_REMOVE_DELAY_MS
+	int "Delay removing power manager restrictions after USB disconnection [ms]"
+	range 0 60000
+	default 3000
+	depends on DESKTOP_USB_PM_ENABLE
+	help
+	  Delay in milliseconds before removing power manager level restriction
+	  after USB is disconnected. This is used to delay the system off after
+	  USB disconnection. While disconnecting an USB cable, an USB suspended
+	  state might be reported. The USB suspended state triggers force power
+	  down sequence which makes CAF power manager instantly suspend the
+	  application. This option allows user to take actions, like e.g. restart
+	  BLE advertising, after disconnecting the USB cable without going through
+	  reboot.
+
 config DESKTOP_USB_HID_REPORT_SENT_ON_SOF
 	bool "Submit HID report sent event on USB Start of Frame (SOF) [EXPERIMENTAL]"
 	default y if UDC_DRIVER_HAS_HIGH_SPEED_SUPPORT

applications/nrf_desktop/src/modules/usb_state_pm.c

@@ -19,6 +19,16 @@ LOG_MODULE_REGISTER(MODULE, CONFIG_DESKTOP_USB_STATE_LOG_LEVEL);
 #include <caf/events/force_power_down_event.h>
 
 
+static bool initialized;
+static struct k_work_delayable pm_restrict_remove_work;
+
+static void pm_restrict_remove_work_fn(struct k_work *work)
+{
+	ARG_UNUSED(work);
+
+	power_manager_restrict(MODULE_IDX(MODULE), POWER_MANAGER_LEVEL_MAX);
+}
+
 static void update_pm_policy_latency_req(bool enable)
 {
 	static bool enabled;
@@ -45,11 +55,18 @@ static bool app_event_handler(const struct app_event_header *aeh)
 		const struct usb_state_event *event = cast_usb_state_event(aeh);
 
 		LOG_DBG("USB state change detected");
+		__ASSERT_NO_MSG(initialized);
 
 		if (IS_ENABLED(CONFIG_DESKTOP_USB_PM_REQ_NO_PM_LATENCY)) {
 			update_pm_policy_latency_req(event->state == USB_STATE_ACTIVE);
 		}
 
+		if ((CONFIG_DESKTOP_USB_PM_RESTRICT_REMOVE_DELAY_MS > 0) &&
+		    (event->state != USB_STATE_DISCONNECTED)) {
+			/* Cancel the work if it is scheduled. */
+			(void)k_work_cancel_delayable(&pm_restrict_remove_work);
+		}
+
 		switch (event->state) {
 		case USB_STATE_POWERED:
 			power_manager_restrict(MODULE_IDX(MODULE), POWER_MANAGER_LEVEL_SUSPENDED);
@@ -58,7 +75,28 @@ static bool app_event_handler(const struct app_event_header *aeh)
 			power_manager_restrict(MODULE_IDX(MODULE), POWER_MANAGER_LEVEL_ALIVE);
 			break;
 		case USB_STATE_DISCONNECTED:
-			power_manager_restrict(MODULE_IDX(MODULE), POWER_MANAGER_LEVEL_MAX);
+			if (CONFIG_DESKTOP_USB_PM_RESTRICT_REMOVE_DELAY_MS > 0) {
+				/* Remove the restriction after the delay to allow the user to
+				 * take actions like e.g. restart BLE advertising without going
+				 * through system off.
+				 */
+				(void)k_work_schedule(
+					&pm_restrict_remove_work,
+					K_MSEC(CONFIG_DESKTOP_USB_PM_RESTRICT_REMOVE_DELAY_MS));
+			} else {
+				power_manager_restrict(MODULE_IDX(MODULE), POWER_MANAGER_LEVEL_MAX);
+			}
+			/* When disconnecting USB cable, the USB_STATE_SUSPENDED event may
+			 * or may not appear before the USB_STATE_DISCONNECTED event. Add power
+			 * manager restriction and force power down for application to behave
+			 * consistently even if the USB_STATE_SUSPENDED event doesn't appear. Don't
+			 * add restriction if the restriction removal delay is set to 0.
+			 */
+			if (CONFIG_DESKTOP_USB_PM_RESTRICT_REMOVE_DELAY_MS > 0) {
+				power_manager_restrict(MODULE_IDX(MODULE),
+						       POWER_MANAGER_LEVEL_SUSPENDED);
+			}
+			force_power_down();
 			break;
 		case USB_STATE_SUSPENDED:
 			LOG_DBG("USB suspended");
@@ -76,9 +114,11 @@ static bool app_event_handler(const struct app_event_header *aeh)
 		const struct module_state_event *event = cast_module_state_event(aeh);
 
 		if (check_state(event, MODULE_ID(main), MODULE_STATE_READY)) {
-			static bool initialized;
-
 			__ASSERT_NO_MSG(!initialized);
+			if (CONFIG_DESKTOP_USB_PM_RESTRICT_REMOVE_DELAY_MS > 0) {
+				k_work_init_delayable(&pm_restrict_remove_work,
+						      pm_restrict_remove_work_fn);
+			}
 			initialized = true;
 		}
 		return false;