mimxrt: Set the uart ioctl write poll flag properly.

robert-hh · robert-hh · commit d188f17039bc · 2022-08-29T13:05:46.000+02:00
It was always set to True. The change adds a check to the tx
status flag which is set when all data is transferred.
diff --git a/ports/mimxrt/machine_uart.c b/ports/mimxrt/machine_uart.c
@@ -425,7 +425,7 @@ 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 {
