diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 724ebf82f2cd..493fc4742895 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -2485,6 +2485,9 @@ static int send_break(struct tty_struct *tty, unsigned int duration)
 	if (!retval) {
 		msleep_interruptible(duration);
 		retval = tty->ops->break_ctl(tty, 0);
+	} else if (retval == -EOPNOTSUPP) {
+		/* some drivers can tell only dynamically */
+		retval = 0;
 	}
 	tty_write_unlock(tty);
 
diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index a1f4e1ead97f..0e7439dba8fe 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -916,6 +916,9 @@ static int acm_tty_break_ctl(struct tty_struct *tty, int state)
 	struct acm *acm = tty->driver_data;
 	int retval;
 
+	if (!(acm->ctrl_caps & USB_CDC_CAP_BRK))
+		return -EOPNOTSUPP;
+
 	retval = acm_send_break(acm, state ? 0xffff : 0);
 	if (retval < 0)
 		dev_dbg(&acm->control->dev,