---

yaml
---
r: 235530
b: refs/heads/master
c: 0d0389e
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 95926d2db6256e08d06b753752a0d903a0580acc
+refs/heads/master: 0d0389e5414c8950b1613e8bdc74289cde3d6d98

trunk/drivers/tty/serial/8250.c

@@ -954,6 +954,23 @@ static int broken_efr(struct uart_8250_port *up)
 	return 0;
 }
 
+static inline int ns16550a_goto_highspeed(struct uart_8250_port *up)
+{
+	unsigned char status;
+
+	status = serial_in(up, 0x04); /* EXCR2 */
+#define PRESL(x) ((x) & 0x30)
+	if (PRESL(status) == 0x10) {
+		/* already in high speed mode */
+		return 0;
+	} else {
+		status &= ~0xB0; /* Disable LOCK, mask out PRESL[01] */
+		status |= 0x10;  /* 1.625 divisor for baud_base --> 921600 */
+		serial_outp(up, 0x04, status);
+	}
+	return 1;
+}
+
 /*
  * We know that the chip has FIFOs.  Does it have an EFR?  The
  * EFR is located in the same register position as the IIR and
@@ -1025,12 +1042,8 @@ static void autoconfig_16550a(struct uart_8250_port *up)
 			quot = serial_dl_read(up);
 			quot <<= 3;
 
-			status1 = serial_in(up, 0x04); /* EXCR2 */
-			status1 &= ~0xB0; /* Disable LOCK, mask out PRESL[01] */
-			status1 |= 0x10;  /* 1.625 divisor for baud_base --> 921600 */
-			serial_outp(up, 0x04, status1);
-
-			serial_dl_write(up, quot);
+			if (ns16550a_goto_highspeed(up))
+				serial_dl_write(up, quot);
 
 			serial_outp(up, UART_LCR, 0);
 
@@ -3025,15 +3038,10 @@ void serial8250_resume_port(int line)
 	struct uart_8250_port *up = &serial8250_ports[line];
 
 	if (up->capabilities & UART_NATSEMI) {
-		unsigned char tmp;
-
 		/* Ensure it's still in high speed mode */
 		serial_outp(up, UART_LCR, 0xE0);
 
-		tmp = serial_in(up, 0x04); /* EXCR2 */
-		tmp &= ~0xB0; /* Disable LOCK, mask out PRESL[01] */
-		tmp |= 0x10;  /* 1.625 divisor for baud_base --> 921600 */
-		serial_outp(up, 0x04, tmp);
+		ns16550a_goto_highspeed(up);
 
 		serial_outp(up, UART_LCR, 0);
 		up->port.uartclk = 921600*16;