Claw back some internal ram

- 'main' doesn't need 12k of internal ram
 - lvgl's draw task doesn't need that much either
 - also lower the bg worker stack sizes whilst we're here, since they've got tons over headroom

lib/lvgl/src/draw/sw/lv_draw_sw.c

@@ -143,7 +143,7 @@ void lv_draw_sw_init(void)
         draw_sw_unit->base_unit.delete_cb = LV_USE_OS ? lv_draw_sw_delete : NULL;
 
 #if LV_USE_OS
-        lv_thread_init(&draw_sw_unit->thread, LV_THREAD_PRIO_HIGH, render_thread_cb, 8 * 1024, draw_sw_unit);
+        lv_thread_init(&draw_sw_unit->thread, LV_THREAD_PRIO_HIGH, render_thread_cb, 4 * 1024, draw_sw_unit);
 #endif
     }
 

sdkconfig.common

@@ -44,7 +44,7 @@ CONFIG_SPIRAM_ALLOW_STACK_EXTERNAL_MEMORY=y
 CONFIG_SPIRAM_OCCUPY_HSPI_HOST=y
 CONFIG_RINGBUF_PLACE_FUNCTIONS_INTO_FLASH=y
 CONFIG_ESP_DEFAULT_CPU_FREQ_MHZ_240=y
-CONFIG_ESP_MAIN_TASK_STACK_SIZE=12000
+CONFIG_ESP_MAIN_TASK_STACK_SIZE=4096
 CONFIG_ESP_INT_WDT_TIMEOUT_MS=5000
 CONFIG_ESP_TASK_WDT_PANIC=y
 CONFIG_ESP_TASK_WDT_TIMEOUT_S=10

src/tasks/tasks.cpp

@@ -64,7 +64,7 @@ auto AllocateStack<Type::kAudioConverter>() -> std::span<StackType_t> {
 // an eye-wateringly large amount of stack.
 template <>
 auto AllocateStack<Type::kBackgroundWorker>() -> std::span<StackType_t> {
-  std::size_t size = 64 * 1024;
+  std::size_t size = 32 * 1024;
   return {static_cast<StackType_t*>(heap_caps_malloc(size, MALLOC_CAP_SPIRAM)),
           size};
 }