Patch for connection dropout issue

connection-drop-fix.patch

diff --git a/components/openthread/src/port/esp_openthread_uart.c b/components/openthread/src/port/esp_openthread_uart.c
index 1e19af66e5..b2cb6a6395 100644
--- a/components/openthread/src/port/esp_openthread_uart.c
+++ b/components/openthread/src/port/esp_openthread_uart.c
@@ -8,7 +8,6 @@

 #include <errno.h>
 #include <fcntl.h>
-#include <sys/select.h>

 #include "esp_check.h"
 #include "esp_err.h"
@@ -52,17 +51,17 @@ otError otPlatUartFlush(void)

 otError otPlatUartSend(const uint8_t *buf, uint16_t buf_length)
 {
-    int rval = write(s_uart_fd, buf, buf_length);
+    int rval = 0;
+
+    while (rval != (int)buf_length) {
+        rval = write(s_uart_fd, buf, buf_length);
+    }

     // DIG-727
 #if CONFIG_OPENTHREAD_RCP_USB_SERIAL_JTAG
     usb_serial_jtag_ll_txfifo_flush();
 #endif

-    if (rval != (int)buf_length) {
-        return OT_ERROR_FAILED;
-    }
-
     otPlatUartSendDone();

     return OT_ERROR_NONE;