0900-bt-mtk-serial-fix.patch

--- a/drivers/tty/serial/8250/8250.h
+++ b/drivers/tty/serial/8250/8250.h
@@ -82,6 +82,7 @@ struct serial8250_config {
 #define UART_CAP_MINI	(1 << 17)	/* Mini UART on BCM283X family lacks:
 					 * STOP PARITY EPAR SPAR WLEN5 WLEN6
 					 */
+#define UART_CAP_NMOD	(1 << 18)	/* UART doesn't do termios */
 
 #define UART_BUG_QUOT	(1 << 0)	/* UART has buggy quot LSB */
 #define UART_BUG_TXEN	(1 << 1)	/* UART has buggy TX IIR status */
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -290,7 +290,7 @@ static const struct serial8250_config ua
 		.tx_loadsz	= 16,
 		.fcr		= UART_FCR_ENABLE_FIFO |
 				  UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT,
-		.flags		= UART_CAP_FIFO,
+		.flags		= UART_CAP_FIFO | UART_CAP_NMOD,
 	},
 	[PORT_NPCM] = {
 		.name		= "Nuvoton 16550",
@@ -2561,6 +2561,11 @@ serial8250_do_set_termios(struct uart_po
 	unsigned long flags;
 	unsigned int baud, quot, frac = 0;
 
+	if (up->capabilities & UART_CAP_NMOD) {
+		termios->c_cflag = 0;
+		return;
+	}
+
 	if (up->capabilities & UART_CAP_MINI) {
 		termios->c_cflag &= ~(CSTOPB | PARENB | PARODD | CMSPAR);
 		if ((termios->c_cflag & CSIZE) == CS5 ||