From 59d08d446743d8aaedfeb4c6bce55511fcbfa883 Mon Sep 17 00:00:00 2001
From: Melissa LeBlanc-Williams <melissa@adafruit.com>
Date: Thu, 8 Apr 2021 14:22:44 -0700
Subject: [PATCH 1/2] dreiver/i2c: delete i2c cmd_mux semaphore more cleanly

Merges https://github.com/espressif/esp-idf/pull/6847
---
 components/driver/i2c.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/components/driver/i2c.c b/components/driver/i2c.c
index 30f743509d..c75e204c02 100644
--- a/components/driver/i2c.c
+++ b/components/driver/i2c.c
@@ -367,7 +367,9 @@ esp_err_t i2c_driver_delete(i2c_port_t i2c_num)
     p_i2c->intr_handle = NULL;
 
     if (p_i2c->cmd_mux) {
+        // Let any command in progress finish.
         xSemaphoreTake(p_i2c->cmd_mux, portMAX_DELAY);
+        xSemaphoreGive(p_i2c->cmd_mux);
         vSemaphoreDelete(p_i2c->cmd_mux);
     }
     if (p_i2c_obj[i2c_num]->cmd_evt_queue) {

From 8872c6a3ac0ce941936071634cfa5acf36e08e41 Mon Sep 17 00:00:00 2001
From: laokaiyao <laokaiyao@espressif.com>
Date: Fri, 7 May 2021 18:15:00 +0800
Subject: [PATCH 2/2] driver/i2c: add notes to i2c deleteing function

---
 components/driver/include/driver/i2c.h    | 3 +++
 docs/en/api-reference/peripherals/i2c.rst | 1 +
 2 files changed, 4 insertions(+)

diff --git a/components/driver/include/driver/i2c.h b/components/driver/include/driver/i2c.h
index 197bca2971..01323a2858 100644
--- a/components/driver/include/driver/i2c.h
+++ b/components/driver/include/driver/i2c.h
@@ -68,6 +68,9 @@ esp_err_t i2c_driver_install(i2c_port_t i2c_num, i2c_mode_t mode, size_t slv_rx_
 /**
  * @brief I2C driver delete
  *
+ * @note This function does not guarantee thread safety.
+ *       Please make sure that no thread will continuously hold semaphores before calling the delete function.
+ *
  * @param i2c_num I2C port number
  *
  * @return
diff --git a/docs/en/api-reference/peripherals/i2c.rst b/docs/en/api-reference/peripherals/i2c.rst
index 5795041cd4..a837de1ae9 100644
--- a/docs/en/api-reference/peripherals/i2c.rst
+++ b/docs/en/api-reference/peripherals/i2c.rst
@@ -238,6 +238,7 @@ Delete Driver
 
 When the I2C communication is established with the function :cpp:func:`i2c_driver_install` and is not required for some substantial amount of time, the driver may be deinitialized to release allocated resources by calling :cpp:func:`i2c_driver_delete`.
 
+Before calling :cpp:func:`i2c_driver_delete` to remove i2c driver, please make sure that all threads have stopped using the driver in any way, because this function does not guarantee thread safety.
 
 Application Example
 -------------------