Let's merge and fix possible regressions!

Hi @FASTSHIFT thanks for adding LVGL 8 support! I have a question: Should we insert lv_tick_inc() into the LVGL Task Loop, like this?

From lvgldemo.c:

  /* Handle LVGL tasks */
  while (1)
    {
      uint32_t idle;
      idle = lv_timer_handler();

      /* Minimum sleep of 1ms */
      idle = idle ? idle : 1;
      usleep(idle * 1000);

      // Inserted this: Increment LVGL Tick Count by 1 millisecond
      lv_tick_inc(1);
    }

Before Adding lv_tick_inc(): When we run lvgldemo on PINE64 PinePhone, the app doesn't read touch input from /dev/input0.

Also the LVGL Log shows: It seems lv_tick_inc() is not called

After Adding lv_tick_inc(): lvgldemo on PinePhone correctly handles the touch input. (See this)

I'm not sure if my parameter to lv_tick_inc() is correct. Maybe we need to compute the actual elapsed milliseconds using the System Timer? This might help to reduce the lag that we see in the demo video.

Thanks for looking into this :-)

@lupyuen
The tick of LVGL should not be placed in the same thread as the rendering, because the execution time of lv_timer_handler is not deterministic, which will cause a large error in LVGL tick.
We should let LVGL use the system timestamp provided by lv_port_tick, just need to set two options:

CONFIG_LV_TICK_CUSTOM=y
CONFIG_LV_TICK_CUSTOM_INCLUDE="port/lv_port_tick.h"

@FASTSHIFT thank you so much! LVGL on PinePhone works great now, it feels very responsive: Demo on YouTube

(Compare with the previous laggy demo)

I have documented the settings here: "LVGL Calls Our Driver"

Thanks again! :-)