From 35e9cf2db255d08a4dcf612e81405e69cabd4403 Mon Sep 17 00:00:00 2001
From: Mirco Pizzichini <mirco.pizzichini@isemar.biz>
Date: Wed, 26 Apr 2023 14:00:12 +0200
Subject: [PATCH] Add lock to protect concurrent i2c transactions performed by
 different tasks

---
 libraries/Wire/src/Wire.cpp | 53 ++++++++++++++++++++-----------------
 libraries/Wire/src/Wire.h   |  2 +-
 2 files changed, 30 insertions(+), 25 deletions(-)

diff --git a/libraries/Wire/src/Wire.cpp b/libraries/Wire/src/Wire.cpp
index ae05e2752a0..ca6a7f1d4e5 100644
--- a/libraries/Wire/src/Wire.cpp
+++ b/libraries/Wire/src/Wire.cpp
@@ -48,7 +48,7 @@ TwoWire::TwoWire(uint8_t bus_num)
     ,_timeOutMillis(50)
     ,nonStop(false)
 #if !CONFIG_DISABLE_HAL_LOCKS
-    ,nonStopTask(NULL)
+    ,currentTaskHandle(NULL)
     ,lock(NULL)
 #endif
     ,is_slave(false)
@@ -412,15 +412,15 @@ void TwoWire::beginTransmission(uint16_t address)
         return;
     }
 #if !CONFIG_DISABLE_HAL_LOCKS
-    if(nonStop && nonStopTask == xTaskGetCurrentTaskHandle()){
-        log_e("Unfinished Repeated Start transaction! Expected requestFrom, not beginTransmission! Clearing...");
-        //release lock
-        xSemaphoreGive(lock);
-    }
-    //acquire lock
-    if(lock == NULL || xSemaphoreTake(lock, portMAX_DELAY) != pdTRUE){
-        log_e("could not acquire lock");
-        return;
+    TaskHandle_t task = xTaskGetCurrentTaskHandle();
+    if (currentTaskHandle != task)
+    {
+        //acquire lock
+        if(lock == NULL || xSemaphoreTake(lock, portMAX_DELAY) != pdTRUE){
+            log_e("could not acquire lock");
+            return;
+        }
+        currentTaskHandle = task;
     }
 #endif
     nonStop = false;
@@ -452,15 +452,13 @@ uint8_t TwoWire::endTransmission(bool sendStop)
     if(sendStop){
         err = i2cWrite(num, txAddress, txBuffer, txLength, _timeOutMillis);
 #if !CONFIG_DISABLE_HAL_LOCKS
+        currentTaskHandle = NULL;
         //release lock
         xSemaphoreGive(lock);
 #endif
     } else {
         //mark as non-stop
         nonStop = true;
-#if !CONFIG_DISABLE_HAL_LOCKS
-        nonStopTask = xTaskGetCurrentTaskHandle();
-#endif
     }
     switch(err){
         case ESP_OK: return 0;
@@ -482,13 +480,26 @@ size_t TwoWire::requestFrom(uint16_t address, size_t size, bool sendStop)
         return 0;
     }
     esp_err_t err = ESP_OK;
-    if(nonStop
 #if !CONFIG_DISABLE_HAL_LOCKS
-    && nonStopTask == xTaskGetCurrentTaskHandle()
-#endif
-    ){
+    TaskHandle_t task = xTaskGetCurrentTaskHandle();
+    if (currentTaskHandle != task)
+    {
+        //acquire lock
+        if(lock == NULL || xSemaphoreTake(lock, portMAX_DELAY) != pdTRUE){
+            log_e("could not acquire lock");
+            return 0;
+        }
+        currentTaskHandle = task;
+    }
+#endif  
+    if(nonStop){
         if(address != txAddress){
             log_e("Unfinished Repeated Start transaction! Expected address do not match! %u != %u", address, txAddress);
+#if !CONFIG_DISABLE_HAL_LOCKS
+            currentTaskHandle = NULL;
+            //release lock
+            xSemaphoreGive(lock);
+#endif
             return 0;
         }
         nonStop = false;
@@ -499,13 +510,6 @@ size_t TwoWire::requestFrom(uint16_t address, size_t size, bool sendStop)
             log_e("i2cWriteReadNonStop returned Error %d", err);
         }
     } else {
-#if !CONFIG_DISABLE_HAL_LOCKS
-        //acquire lock
-        if(lock == NULL || xSemaphoreTake(lock, portMAX_DELAY) != pdTRUE){
-            log_e("could not acquire lock");
-            return 0;
-        }
-#endif
         rxIndex = 0;
         rxLength = 0;
         err = i2cRead(num, address, rxBuffer, size, _timeOutMillis, &rxLength);
@@ -514,6 +518,7 @@ size_t TwoWire::requestFrom(uint16_t address, size_t size, bool sendStop)
         }
     }
 #if !CONFIG_DISABLE_HAL_LOCKS
+    currentTaskHandle = NULL;
     //release lock
     xSemaphoreGive(lock);
 #endif
diff --git a/libraries/Wire/src/Wire.h b/libraries/Wire/src/Wire.h
index 339b0e2866f..646ee4be4a3 100644
--- a/libraries/Wire/src/Wire.h
+++ b/libraries/Wire/src/Wire.h
@@ -64,7 +64,7 @@ class TwoWire: public Stream
     uint32_t _timeOutMillis;
     bool nonStop;
 #if !CONFIG_DISABLE_HAL_LOCKS
-    TaskHandle_t nonStopTask;
+    TaskHandle_t currentTaskHandle;
     SemaphoreHandle_t lock;
 #endif
 private: