Drain serial port before changing speed

Signed-off-by: Keith Packard <keithp@keithp.com>

diff --git a/src/ao_serial.c b/src/ao_serial.c
index 7bc11b979ac38137abd5e62c4a263711c5f097bf..4155e776934ac59f196e67642aa23d462d011025 100644 (file)
--- a/src/ao_serial.c
+++ b/src/ao_serial.c
@@ -75,6 +75,13 @@ ao_serial_putchar(char c) __critical
        ao_serial_tx1_start();
 }
 
+static void
+ao_serial_drain(void) __critical
+{
+       while (!ao_fifo_empty(ao_usart1_tx_fifo))
+               ao_sleep(&ao_usart1_tx_fifo);
+}
+
 static void
 send_serial(void)
 {
@@ -115,6 +122,9 @@ static const struct {
 void
 ao_serial_set_speed(uint8_t speed)
 {
+       ao_serial_drain();
+       if (speed > AO_SERIAL_SPEED_57600)
+               return;
        U1BAUD = ao_serial_speeds[speed].baud;
        U1GCR = ao_serial_speeds[speed].gcr;
 }