From b71c406e704f1d751484404737a91c2b8035ddbb Mon Sep 17 00:00:00 2001
From: Edward Firmo <94725493+edwardtfn@users.noreply.github.com>
Date: Wed, 1 Apr 2026 01:04:07 +0200
Subject: [PATCH] [uart] fix baud rate not applied on `load_settings()` for
 ESP32 (IDF) (#15341)

---
 .../uart/uart_component_esp_idf.cpp           | 25 ++++++++++++-------
 1 file changed, 16 insertions(+), 9 deletions(-)

diff --git a/esphome/components/uart/uart_component_esp_idf.cpp b/esphome/components/uart/uart_component_esp_idf.cpp
index 6d9d44e97f..93e43e0372 100644
--- a/esphome/components/uart/uart_component_esp_idf.cpp
+++ b/esphome/components/uart/uart_component_esp_idf.cpp
@@ -147,6 +147,20 @@ void IDFUARTComponent::load_settings(bool dump_config) {
     return;
   }
 
+  // uart_param_config must be called after uart_driver_install and before any
+  // other uart_set_*() calls. The driver installation resets the UART peripheral
+  // registers to their default state, overwriting any previously configured baud
+  // rate or framing settings. Calling uart_param_config here ensures the requested
+  // settings are applied after the reset and before pin routing, inversion, and
+  // threshold configuration.
+  uart_config_t uart_config = this->get_config_();
+  err = uart_param_config(this->uart_num_, &uart_config);
+  if (err != ESP_OK) {
+    ESP_LOGW(TAG, "uart_param_config failed: %s", esp_err_to_name(err));
+    this->mark_failed();
+    return;
+  }
+
   int8_t tx = this->tx_pin_ != nullptr ? this->tx_pin_->get_pin() : -1;
   int8_t rx = this->rx_pin_ != nullptr ? this->rx_pin_->get_pin() : -1;
   int8_t flow_control = this->flow_control_pin_ != nullptr ? this->flow_control_pin_->get_pin() : -1;
@@ -214,22 +228,15 @@ void IDFUARTComponent::load_settings(bool dump_config) {
     return;
   }
 
+  // Per ESP-IDF docs, uart_set_mode() must be called only after uart_driver_install().
   auto mode = this->flow_control_pin_ != nullptr ? UART_MODE_RS485_HALF_DUPLEX : UART_MODE_UART;
-  err = uart_set_mode(this->uart_num_, mode);  // per docs, must be called only after uart_driver_install()
+  err = uart_set_mode(this->uart_num_, mode);
   if (err != ESP_OK) {
     ESP_LOGW(TAG, "uart_set_mode failed: %s", esp_err_to_name(err));
     this->mark_failed();
     return;
   }
 
-  uart_config_t uart_config = this->get_config_();
-  err = uart_param_config(this->uart_num_, &uart_config);
-  if (err != ESP_OK) {
-    ESP_LOGW(TAG, "uart_param_config failed: %s", esp_err_to_name(err));
-    this->mark_failed();
-    return;
-  }
-
 #ifdef USE_UART_WAKE_LOOP_ON_RX
   // Register ISR callback to wake the main loop when UART data arrives.
   // The callback runs in ISR context and uses vTaskNotifyGiveFromISR() to