From e85dc394adb4203b26124032ef035dbe38d15eec Mon Sep 17 00:00:00 2001
From: Jonathan Swoboda <154711427+swoboda1337@users.noreply.github.com>
Date: Sun, 23 Mar 2025 20:26:46 -0400
Subject: [PATCH] fix(i2c): Fix clear bus issue in legacy i2c driver,

Closes https://github.com/espressif/esp-idf/pull/15638
---
 components/driver/i2c/i2c.c | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/components/driver/i2c/i2c.c b/components/driver/i2c/i2c.c
index b7b2291e0c..42d9243012 100644
--- a/components/driver/i2c/i2c.c
+++ b/components/driver/i2c/i2c.c
@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2015-2024 Espressif Systems (Shanghai) CO LTD
+ * SPDX-FileCopyrightText: 2015-2025 Espressif Systems (Shanghai) CO LTD
  *
  * SPDX-License-Identifier: Apache-2.0
  */
@@ -68,6 +68,7 @@ static const char *I2C_TAG = "i2c";
 #define I2C_CMD_USER_ALLOC_ERR_STR     "i2c command link allocation error: the buffer provided is too small."
 #define I2C_TRANS_MODE_ERR_STR         "i2c trans mode error"
 #define I2C_MODE_ERR_STR               "i2c mode error"
+#define I2C_CLEAR_BUS_ERR_STR          "clear bus error"
 #define I2C_SDA_IO_ERR_STR             "sda gpio number error"
 #define I2C_SCL_IO_ERR_STR             "scl gpio number error"
 #define I2C_SCL_SDA_EQUAL_ERR_STR      "scl and sda gpio numbers are the same"
@@ -126,6 +127,8 @@ static const char *I2C_TAG = "i2c";
 #define I2C_RCC_ATOMIC()
 #endif
 
+#define I2C_CLR_BUS_TIMEOUT_MS        (50)  // 50ms is sufficient for clearing the bus
+
 /**
  * I2C bus are defined in the header files, let's check that the values are correct
  */
@@ -657,6 +660,7 @@ esp_err_t i2c_get_data_mode(i2c_port_t i2c_num, i2c_trans_mode_t *tx_trans_mode,
  **/
 static esp_err_t i2c_master_clear_bus(i2c_port_t i2c_num)
 {
+    esp_err_t ret = ESP_OK;
 #if !SOC_I2C_SUPPORT_HW_CLR_BUS
     const int scl_half_period = I2C_CLR_BUS_HALF_PERIOD_US; // use standard 100kHz data rate
     int i = 0;
@@ -685,11 +689,22 @@ static esp_err_t i2c_master_clear_bus(i2c_port_t i2c_num)
     i2c_set_pin(i2c_num, sda_io, scl_io, 1, 1, I2C_MODE_MASTER);
 #else
     i2c_ll_master_clr_bus(i2c_context[i2c_num].hal.dev, I2C_CLR_BUS_SCL_NUM, true);
+    // If the i2c master clear bus state machine got disturbed when working, it would go into error state.
+    // The solution here is to use freertos tick counter to set a timeout threshold. If it doesn't return on time,
+    // return invalid state and turn off the state machine as its always wrong.
+    TickType_t start_tick = xTaskGetTickCount();
+    const TickType_t timeout_ticks = pdMS_TO_TICKS(I2C_CLR_BUS_TIMEOUT_MS);
     while (i2c_ll_master_is_bus_clear_done(i2c_context[i2c_num].hal.dev)) {
+        if ((xTaskGetTickCount() - start_tick) > timeout_ticks) {
+            ESP_LOGE(I2C_TAG, I2C_CLEAR_BUS_ERR_STR);
+            i2c_ll_master_clr_bus(i2c_context[i2c_num].hal.dev, 0, false);
+            ret = ESP_ERR_INVALID_STATE;
+            break;
+        }
     }
     i2c_ll_update(i2c_context[i2c_num].hal.dev);
 #endif
-    return ESP_OK;
+    return ret;
 }
 
 /**if the power and SDA/SCL wires are in proper condition, everything works find with reading the slave.