From 886745326ebe9bafccde1a570d6cb0995c21dcaa Mon Sep 17 00:00:00 2001
From: houwenxiang <houwenxiang@espressif.com>
Date: Mon, 16 Mar 2020 20:37:12 +0800
Subject: [PATCH] driver(UART): fix uart driver missing txfifo reset issue.

closes https://github.com/espressif/esp-idf/issues/4908
---
 components/driver/uart.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/components/driver/uart.c b/components/driver/uart.c
index 2fc8dbf0bb..fe2a5cc8e7 100644
--- a/components/driver/uart.c
+++ b/components/driver/uart.c
@@ -631,7 +631,10 @@ esp_err_t uart_param_config(uart_port_t uart_num, const uart_config_t *uart_conf
     uart_hal_set_tx_idle_num(&(uart_context[uart_num].hal), UART_TX_IDLE_NUM_DEFAULT);
     uart_hal_set_hw_flow_ctrl(&(uart_context[uart_num].hal), uart_config->flow_ctrl, uart_config->rx_flow_ctrl_thresh);
     UART_EXIT_CRITICAL(&(uart_context[uart_num].spinlock));
+    // The module reset do not reset TX and RX memory.
+    // reset FIFO to avoid garbage data remained in the FIFO.
     uart_hal_rxfifo_rst(&(uart_context[uart_num].hal));
+    uart_hal_txfifo_rst(&(uart_context[uart_num].hal));
     return ESP_OK;
 }