modem: cmux: Send disconnect event only after responding to CLD

If we immediately send disconnected event when CLD is received,
we might close the UART pipe before the response is actually send.

Also, shutdown_handler should not retry indefinitely.

Signed-off-by: Seppo Takalo <[email protected]>

Author: SeppoTakalo

subsys/modem/modem_cmux.c

@@ -451,6 +451,17 @@ static void modem_cmux_on_fcoff_command(struct modem_cmux *cmux)
 	modem_cmux_acknowledge_received_frame(cmux);
 }
 
+static void disconnect(struct modem_cmux *cmux)
+{
+	LOG_DBG("CMUX disconnected");
+	k_work_cancel_delayable(&cmux->disconnect_work);
+	set_state(cmux, MODEM_CMUX_STATE_DISCONNECTED);
+	k_mutex_lock(&cmux->transmit_rb_lock, K_FOREVER);
+	cmux->flow_control_on = false;
+	k_mutex_unlock(&cmux->transmit_rb_lock);
+	modem_cmux_raise_event(cmux, MODEM_CMUX_EVENT_DISCONNECTED);
+}
+
 static void modem_cmux_on_cld_command(struct modem_cmux *cmux, struct modem_cmux_command *command)
 {
 	if (command->type.cr) {
@@ -464,16 +475,11 @@ static void modem_cmux_on_cld_command(struct modem_cmux *cmux, struct modem_cmux
 	}
 
 	if (cmux->state == MODEM_CMUX_STATE_DISCONNECTING) {
-		k_work_cancel_delayable(&cmux->disconnect_work);
+		disconnect(cmux);
+	} else {
+		set_state(cmux, MODEM_CMUX_STATE_DISCONNECTING);
+		k_work_schedule(&cmux->disconnect_work, MODEM_CMUX_T1_TIMEOUT);
 	}
-
-	LOG_DBG("CMUX disconnected");
-	set_state(cmux, MODEM_CMUX_STATE_DISCONNECTED);
-	k_mutex_lock(&cmux->transmit_rb_lock, K_FOREVER);
-	cmux->flow_control_on = false;
-	k_mutex_unlock(&cmux->transmit_rb_lock);
-
-	modem_cmux_raise_event(cmux, MODEM_CMUX_EVENT_DISCONNECTED);
 }
 
 static void modem_cmux_on_control_frame_ua(struct modem_cmux *cmux)
@@ -1150,7 +1156,12 @@ static void modem_cmux_disconnect_handler(struct k_work *item)
 	struct modem_cmux_command *command;
 	uint8_t data[2];
 
-	set_state(cmux, MODEM_CMUX_STATE_DISCONNECTING);
+	if (cmux->state == MODEM_CMUX_STATE_DISCONNECTING) {
+		disconnect(cmux);
+	} else {
+		set_state(cmux, MODEM_CMUX_STATE_DISCONNECTING);
+		k_work_schedule(&cmux->disconnect_work, MODEM_CMUX_T1_TIMEOUT);
+	}
 
 	command = modem_cmux_command_wrap(data);
 	command->type.ea = 1;

tests/subsys/modem/modem_cmux_pair/src/main.c

@@ -507,9 +507,10 @@ ZTEST(modem_cmux_pair, test_modem_cmux_disconnect_connect)
 	modem_backend_mock_reset(&bus_mock_dte);
 	zassert_true(modem_cmux_disconnect_async(&cmux_dte) == 0, "Failed to disconnect CMUX");
 
-	k_msleep(100);
+	events = k_event_wait_all(&cmux_event_dte, (EVENT_CMUX_DISCONNECTED), false, K_MSEC(660));
+	zassert_true((events & EVENT_CMUX_DISCONNECTED), "Failed to disconnect CMUX");
 
-	events = k_event_wait_all(&cmux_event_dte, (EVENT_CMUX_DISCONNECTED), false, K_MSEC(100));
+	events = k_event_wait_all(&cmux_event_dce, (EVENT_CMUX_DISCONNECTED), false, K_MSEC(660));
 	zassert_true((events & EVENT_CMUX_DISCONNECTED), "Failed to disconnect CMUX");
 
 	/* Reconnect CMUX */
@@ -554,6 +555,9 @@ ZTEST(modem_cmux_pair, test_modem_cmux_disconnect_connect_sync)
 	zassert_true(modem_cmux_disconnect(&cmux_dte) == 0, "Failed to disconnect CMUX");
 	zassert_true(modem_cmux_disconnect(&cmux_dte) == -EALREADY,
 		     "Should already be disconnected");
+
+	events = k_event_wait_all(&cmux_event_dce, (EVENT_CMUX_DISCONNECTED), false, K_MSEC(660));
+	zassert_true((events & EVENT_CMUX_DISCONNECTED), "Failed to disconnect CMUX");
 	zassert_true(modem_cmux_disconnect(&cmux_dce) == -EALREADY,
 		     "Should already be disconnected");