From 443fbcf81c05de00f35b90d8a443837d62073a63 Mon Sep 17 00:00:00 2001
From: robert-hh <robert@hammelrath.com>
Date: Thu, 18 Aug 2022 11:36:08 +0200
Subject: [PATCH] mimxrt/machine_uart: Set the UART ioctl write poll flag
 properly.

It was always set to True.  The change adds a check to the tx status flag
which is set when all data is transferred.
---
 ports/mimxrt/machine_uart.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/ports/mimxrt/machine_uart.c b/ports/mimxrt/machine_uart.c
index 1b0c063334..ab17886926 100644
--- a/ports/mimxrt/machine_uart.c
+++ b/ports/mimxrt/machine_uart.c
@@ -437,7 +437,7 @@ STATIC mp_uint_t machine_uart_ioctl(mp_obj_t self_in, mp_uint_t request, mp_uint
                 ret |= MP_STREAM_POLL_RD;
             }
         }
-        if ((flags & MP_STREAM_POLL_WR)) {
+        if ((flags & MP_STREAM_POLL_WR) && (self->tx_status == kStatus_LPUART_TxIdle)) {
             ret |= MP_STREAM_POLL_WR;
         }
     } else if (request == MP_STREAM_FLUSH) {