Merge pull request paparazzi#1110 from paparazzi/linux_uart_fix

[arch/linux] fix uart driver

- make sure the output flags are properly reset for raw mode.
  Specifically OPOST, clear some others as well to be safe...
- put byte in queue if write was interrupted and only advance extract index if write was successful
  This solves the issue of some bytes not being written (at least on BBB with PREEMPT kernel)

sw/airborne/arch/linux/mcu_periph/uart_arch.c

@@ -32,6 +32,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <errno.h>
 
 #include "serial_port.h"
 
@@ -88,6 +89,7 @@ void uart_transmit(struct uart_periph *periph, uint8_t data)
   uint16_t temp = (periph->tx_insert_idx + 1) % UART_TX_BUFFER_SIZE;
 
   if (temp == periph->tx_extract_idx) {
+    printf("uart tx queue full!\n");
     return;  // no room
   }
 
@@ -100,12 +102,16 @@ void uart_transmit(struct uart_periph *periph, uint8_t data)
     struct SerialPort *port = (struct SerialPort *)(periph->reg_addr);
     int ret = write((int)(port->fd), &data, 1);
     if (ret < 1) {
-      TRACE("w %x [%d]\n", data, ret);
+      TRACE("uart_transmit: write %d failed [%d: %s]\n", data, ret, strerror(errno));
+      /* if write was interrupted, put data into queue */
+      if (errno == EINTR) {
+        periph->tx_buf[periph->tx_insert_idx] = data;
+        periph->tx_insert_idx = temp;
+      }
     }
   }
 }
 
-#include <errno.h>
 
 static inline void uart_handler(struct uart_periph *periph)
 {
@@ -120,10 +126,12 @@ static inline void uart_handler(struct uart_periph *periph)
   if (periph->tx_insert_idx != periph->tx_extract_idx) {
     int ret = write(fd, &(periph->tx_buf[periph->tx_extract_idx]), 1);
     if (ret < 1) {
-      TRACE("w %x [%d: %s]\n", periph->tx_buf[periph->tx_extract_idx], ret, strerror(errno));
+      TRACE("uart_handler: write %x failed [%d: %s]\n", periph->tx_buf[periph->tx_extract_idx], ret, strerror(errno));
+    }
+    else {
+      periph->tx_extract_idx++;
+      periph->tx_extract_idx %= UART_TX_BUFFER_SIZE;
     }
-    periph->tx_extract_idx++;
-    periph->tx_extract_idx %= UART_TX_BUFFER_SIZE;
   } else {
     periph->tx_running = FALSE;   // clear running flag
   }

sw/airborne/arch/linux/serial_port.c

@@ -69,6 +69,9 @@ int  serial_port_open_raw(struct SerialPort *me, const char *device, speed_t spe
   /* local modes  */
   me->cur_termios.c_lflag &= ~(ISIG | ICANON | IEXTEN | ECHO | FLUSHO | PENDIN);
   me->cur_termios.c_lflag |= NOFLSH;
+  /* output modes */
+  me->cur_termios.c_oflag &=~(OPOST|ONLCR|OCRNL|ONOCR|ONLRET);
+
   if (cfsetispeed(&me->cur_termios, speed)) {
     TRACE(TRACE_ERROR, "%s, set term speed failed: %s (%d)\n", device, strerror(errno), errno);
     close(me->fd);