Battery, EPD, and SD support for m5paper

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src/activities/ActivityManager.cpp

@@ -18,6 +18,13 @@
 #include "settings/SettingsActivity.h"
 #include "util/FullScreenMessageActivity.h"
 
+// taskENTER_CRITICAL needs a real spinlock on dual-core targets (classic ESP32,
+// e.g. M5Paper). On the single-core ESP32-C3 a nullptr mux was tolerated, but
+// the dual-core port acquires an inter-core spinlock and asserts on a null
+// pointer (spinlock_acquire, spinlock.h:84). One shared spinlock guards the
+// short waitingTaskHandle critical sections below.
+static portMUX_TYPE activityMux = portMUX_INITIALIZER_UNLOCKED;
+
 void ActivityManager::begin() {
   xTaskCreate(&renderTaskTrampoline, "ActivityManagerRender",
               8192,              // Stack size
@@ -45,10 +52,10 @@ void ActivityManager::renderTaskLoop() {
     }
     // Notify any task blocked in requestUpdateAndWait() that the render is done.
     TaskHandle_t waiter = nullptr;
-    taskENTER_CRITICAL(nullptr);
+    taskENTER_CRITICAL(&activityMux);
     waiter = waitingTaskHandle;
     waitingTaskHandle = nullptr;
-    taskEXIT_CRITICAL(nullptr);
+    taskEXIT_CRITICAL(&activityMux);
     if (waiter) {
       xTaskNotify(waiter, 1, eIncrement);
     }
@@ -279,7 +286,7 @@ void ActivityManager::requestUpdateAndWait() {
   }
 
   // Atomic section to perform checks
-  taskENTER_CRITICAL(nullptr);
+  taskENTER_CRITICAL(&activityMux);
   auto currTaskHandler = xTaskGetCurrentTaskHandle();
   auto mutexHolder = xSemaphoreGetMutexHolder(renderingMutex);
   bool isRenderTask = (currTaskHandler == renderTaskHandle);
@@ -288,7 +295,7 @@ void ActivityManager::requestUpdateAndWait() {
   if (!alreadyWaiting && !isRenderTask && !holdingRenderLock) {
     waitingTaskHandle = currTaskHandler;
   }
-  taskEXIT_CRITICAL(nullptr);
+  taskEXIT_CRITICAL(&activityMux);
 
   // Render task cannot call requestUpdateAndWait() or it will cause a deadlock
   assert(!isRenderTask && "Render task cannot call requestUpdateAndWait()");