3 files changed, 63 insertions, 24 deletions

diff --git a/src/drivers/CMakeLists.txt b/src/drivers/CMakeLists.txt
index 25fdc187..67dc0236 100644
--- a/src/drivers/CMakeLists.txt
+++ b/src/drivers/CMakeLists.txt
@@ -2,5 +2,5 @@ idf_component_register(
   SRCS "touchwheel.cpp" "dac.cpp" "gpio_expander.cpp" "battery.cpp" "storage.cpp" "i2c.cpp"
   "spi.cpp" "display.cpp" "display_init.cpp" "samd.cpp"
   INCLUDE_DIRS "include"
-  REQUIRES "esp_adc" "fatfs" "result" "lvgl" "span")
+  REQUIRES "esp_adc" "fatfs" "result" "lvgl" "span" "tasks")
 target_compile_options(${COMPONENT_LIB} PRIVATE ${EXTRA_WARNINGS})
diff --git a/src/drivers/display.cpp b/src/drivers/display.cpp
index 2888903c..a8aeb935 100644
--- a/src/drivers/display.cpp
+++ b/src/drivers/display.cpp
@@ -21,6 +21,7 @@
 #include "display_init.hpp"
 #include "gpio_expander.hpp"
 #include "soc/soc.h"
+#include "tasks.hpp"
 
 static const char* kTag = "DISPLAY";
 
@@ -49,6 +50,19 @@ static const int kDisplayBufferSize = (kDisplayWidth * kDisplayHeight) / 10;
 DMA_ATTR static lv_color_t sBuffer1[kDisplayBufferSize];
 DMA_ATTR static lv_color_t sBuffer2[kDisplayBufferSize];
 
+struct RenderTaskArgs {
+  std::atomic<bool>* quit;
+  QueueHandle_t work_queue;
+};
+
+struct FlushArgs {
+  lv_disp_drv_t* driver;
+  const lv_area_t* area;
+  lv_color_t* color_map;
+};
+
+void RenderMain(void* raw_args);
+
 namespace drivers {
 
 /*
@@ -138,7 +152,9 @@ auto Display::Create(GpioExpander* expander,
 }
 
 Display::Display(GpioExpander* gpio, spi_device_handle_t handle)
-    : gpio_(gpio), handle_(handle) {}
+    : gpio_(gpio),
+      handle_(handle),
+      worker_task_(tasks::Worker::Start<tasks::Type::kUiFlush>()) {}
 
 Display::~Display() {}
 
@@ -225,31 +241,51 @@ void Display::SendTransaction(TransactionType type,
 void Display::OnLvglFlush(lv_disp_drv_t* disp_drv,
                           const lv_area_t* area,
                           lv_color_t* color_map) {
-  // Ideally we want to complete a single flush as quickly as possible, so grab
-  // the bus for this entire transaction sequence.
-  spi_device_acquire_bus(handle_, portMAX_DELAY);
-
-  // First we need to specify the rectangle of the display we're writing into.
-  uint16_t data[2] = {0, 0};
-
-  data[0] = SPI_SWAP_DATA_TX(area->x1, 16);
-  data[1] = SPI_SWAP_DATA_TX(area->x2, 16);
-  SendCommandWithData(displays::ST77XX_CASET, reinterpret_cast<uint8_t*>(data),
-                      4);
-
-  data[0] = SPI_SWAP_DATA_TX(area->y1, 16);
-  data[1] = SPI_SWAP_DATA_TX(area->y2, 16);
-  SendCommandWithData(displays::ST77XX_RASET, reinterpret_cast<uint8_t*>(data),
-                      4);
+  // area is stack-allocated, so it isn't safe to reference from the flush
+  // thread.
+  lv_area_t area_copy = *area;
+  worker_task_->Dispatch<void>([=, this]() {
+    // Ideally we want to complete a single flush as quickly as possible, so
+    // grab the bus for this entire transaction sequence.
+    spi_device_acquire_bus(handle_, portMAX_DELAY);
+
+    // First we need to specify the rectangle of the display we're writing into.
+    uint16_t data[2] = {0, 0};
+
+    data[0] = SPI_SWAP_DATA_TX(area_copy.x1, 16);
+    data[1] = SPI_SWAP_DATA_TX(area_copy.x2, 16);
+    SendCommandWithData(displays::ST77XX_CASET,
+                        reinterpret_cast<uint8_t*>(data), 4);
+
+    data[0] = SPI_SWAP_DATA_TX(area_copy.y1, 16);
+    data[1] = SPI_SWAP_DATA_TX(area_copy.y2, 16);
+    SendCommandWithData(displays::ST77XX_RASET,
+                        reinterpret_cast<uint8_t*>(data), 4);
+
+    // Now send the pixels for this region.
+    uint32_t size = lv_area_get_width(area) * lv_area_get_height(area);
+    SendCommandWithData(displays::ST77XX_RAMWR,
+                        reinterpret_cast<uint8_t*>(color_map), size * 2);
+
+    spi_device_release_bus(handle_);
+
+    lv_disp_flush_ready(&driver_);
+  });
+}
 
-  // Now send the pixels for this region.
-  uint32_t size = lv_area_get_width(area) * lv_area_get_height(area);
-  SendCommandWithData(displays::ST77XX_RAMWR,
-                      reinterpret_cast<uint8_t*>(color_map), size * 2);
+void RenderMain(void* raw_args) {
+  RenderTaskArgs* args = reinterpret_cast<RenderTaskArgs*>(raw_args);
+  QueueHandle_t queue = args->work_queue;
+  std::atomic<bool>* quit = args->quit;
+  delete args;
 
-  spi_device_release_bus(handle_);
+  while (!quit->load()) {
+    // TODO: flush data here! Yay speed.
+  }
 
-  lv_disp_flush_ready(&driver_);
+  vQueueDelete(queue);
+  delete quit;
+  vTaskDelete(NULL);
 }
 
 }  // namespace drivers
diff --git a/src/drivers/include/display.hpp b/src/drivers/include/display.hpp
index f8a28503..68ddf9fe 100644
--- a/src/drivers/include/display.hpp
+++ b/src/drivers/include/display.hpp
@@ -6,6 +6,7 @@
 #include "driver/spi_master.h"
 #include "lvgl/lvgl.h"
 #include "result.hpp"
+#include "tasks.hpp"
 
 #include "display_init.hpp"
 #include "gpio_expander.hpp"
@@ -37,6 +38,8 @@ class Display {
   GpioExpander* gpio_;
   spi_device_handle_t handle_;
 
+  std::unique_ptr<tasks::Worker> worker_task_;
+
   lv_disp_draw_buf_t buffers_;
   lv_disp_drv_t driver_;
   lv_disp_t* display_ = nullptr;