lvgl: LVGL V8 slow - seems to have a Tick bug.

Perform all steps below and tick them with [x]

• [ X ] Check the related part of the Documentation
• [ X ] Update lvgl to the latest version
• Reproduce the issue in a Simulator

Describe the bug

LVGL Runs very slow. At one point, my clicking actions were delayed by almost a full minute! I have the click tied to a Serial.print so I clicked 3 times and waited, after about 1 minute the 3 clicks came in. Most of the time it is only a little bit slow with a slight delay. This works 100% perfectly on LVGL V7, been running very advanced graphics for over a year on this hardware.

To Reproduce

IMPORTANT. To reproduce this you need a display. I’m using this library with DMA: https://github.com/david-res/ILI948x_t4_mm

This is not a bug regarding that library. It works fine on LVGL V7.

#include <Arduino.h>
#include "ILI948x_t4_mm.h"
ILI948x_t4_mm lcd = ILI948x_t4_mm(17, 16, 5); //(dc, cs, rst)

static void lv_tick_handler(void)
{
  lv_tick_inc(LVGL_TICK_PERIOD);
}

FASTRUN void my_flush_cb(lv_disp_drv_t * disp_drv, const lv_area_t * area, lv_color_t * color_p)
{
    /*The most simple case (but also the slowest) to put all pixels to the screen one-by-one
     *`put_px` is just an example, it needs to implemented by you.*/
      lcd.pushPixels16bitDMA((uint16_t*)(color_p),area->x1, area->y1, area->x2, area->y2);
    /* IMPORTANT!!!
     * Inform the graphics library that you are ready with the flushing*/
      //lv_disp_flush_ready(disp_drv);
}

FASTRUN void flushCB()
{
  lv_disp_flush_ready(&disp_drv);
}

FASTRUN bool touch_glass_input(lv_indev_drv_t * drv, lv_indev_data_t*data) {
  int XL = 0;
  int XH = 0;
  int YL = 0;
  int YH = 0;
  int tStatus = 0;

  XH = readTouchReg(TOUCH_REG_XH);
  XL = readTouchReg(TOUCH_REG_XL);
  YH = readTouchReg(TOUCH_REG_YH);
  YL = readTouchReg(TOUCH_REG_YL);

  // TOUCH INPUT, MAPPED FOR LANDSCAPE
  int x = ((XH & 0x0F) << 8) | XL;
  int y = ((YH & 0x0F) << 8) | YL;
  data->point.x = map(y, 0, 480, 480, 0);
  data->point.y = x;

  tStatus = XH>>6;
  if (tStatus == 1) {
    data->state = LV_INDEV_STATE_REL;
  } else {
    data->state = LV_INDEV_STATE_PR;
  }

  //data->state = LV_INDEV_STATE_PR; // or LV_INDEV_STATE_REL;
  return false; /*No buffering now so no more data read*/
}

void setup() {   
  Serial.begin(115200);
  //FreqMeasure.begin();
  Serial.print(CrashReport);

  pinMode(12, OUTPUT);
  pinMode(14, OUTPUT);
  digitalWrite(12, HIGH);
  digitalWrite(14, HIGH);

  init_touch();

  lcd.begin(20);
  lcd.setRotation(3);
  lcd.onCompleteCB(&flushCB);
  lcd.setFrameRate(68);

  lv_init();

  lv_disp_draw_buf_init(&disp_buf, buf_1, NULL, screenWidth * screenHeight /4);

// INIT THE DISPLAY DRIVERS
  lv_disp_drv_init(&disp_drv);            /*Basic initialization*/
  disp_drv.draw_buf = &disp_buf;          /*Set an initialized buffer*/
  disp_drv.flush_cb = my_flush_cb;        /*Set a flush callback to draw to the display*/
  disp_drv.hor_res = screenWidth;                 /*Set the horizontal resolution in pixels*/
  disp_drv.ver_res = screenHeight;                 /*Set the vertical resolution in pixels*/

  lv_disp_t * disp;
  disp = lv_disp_drv_register(&disp_drv); /*Register the driver and save the created display objects*/

// REGISTER THE TOUCH INPUT DRIVER
  static lv_indev_drv_t indev_drv;
  lv_indev_drv_init(&indev_drv);      /*Basic initialization*/
  indev_drv.type = LV_INDEV_TYPE_POINTER;                 /*See below.*/
  indev_drv.read_cb = touch_glass_input;              /*See below.*/
  /*Register the driver in LVGL and save the created input device object*/
  lv_indev_t * my_indev = lv_indev_drv_register(&indev_drv);

// MAIN SCREEN
  gaugeScreen = lv_obj_create(lv_scr_act());

  // SETTINGS ICON
    // SETTINGS ICON BOTTOM LEFT
      settingsBtnCont = lv_btn_create(gaugeScreen);
      //lv_obj_remove_style_all(settingsBtnCont);
      lv_obj_add_event_cb(settingsBtnCont, event_handler, LV_EVENT_ALL, NULL);
      lv_obj_set_size(settingsBtnCont, 80, 80);
      lv_obj_align(settingsBtnCont, LV_ALIGN_BOTTOM_LEFT, 50, -50);

    // SETTINGS SYMBOL VARIABLE
    //settingsBtn = lv_label_create(settingsBtnCont);
    //lv_label_set_text_static(settingsBtn, LV_SYMBOL_SETTINGS);

  loadStyles();
}

const int loopDelay1 = 1; // Make a request every 500ms
unsigned long timeNow1 = 0;
void loop() {
  if (millis() > timeNow1 + loopDelay1) {
    lv_tick_handler();
    lv_timer_handler();

    timeNow1 = millis();
  }
}

Expected behavior

Real time, butter smooth. Screen is running DMA on a Teensy Micromod at 600mhz. We get above 70fps. Works perfectly in LVGL V7.

Screenshots or video

https://easyupload.io/dbqsrl