Only the first UART interface (ECI) on CP2105 supports break signalling.

Return an error on requests for break state changes for the second
interface (SCI) to avoid transmitting a garbage character and waiting
when break is not supported.

Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/usb/serial/cp210x.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/usb/serial/cp210x.c b/drivers/usb/serial/cp210x.c
index 81e49ed9d147..1e61fe043171 100644
--- a/drivers/usb/serial/cp210x.c
+++ b/drivers/usb/serial/cp210x.c
@@ -1437,8 +1437,14 @@ static int cp210x_tiocmget(struct tty_struct *tty)
 static int cp210x_break_ctl(struct tty_struct *tty, int break_state)
 {
 	struct usb_serial_port *port = tty->driver_data;
+	struct cp210x_serial_private *priv = usb_get_serial_data(port->serial);
 	u16 state;
 
+	if (priv->partnum == CP210X_PARTNUM_CP2105) {
+		if (cp210x_interface_num(port->serial) == 1)
+			return -ENOTTY;
+	}
+
 	if (break_state == 0)
 		state = BREAK_OFF;
 	else
-- 
2.39.3