Hi Francisco,
Thank you very much for your warm welcome and for the kind answer.
I could easily made 180 degrees software rotation by adding “disp_drv.sw_rotate=1;” into “void lvgl_init(screen_dev_t *screen_dev)” function in “RIOT/pkg/lvgl/lvgl.c”, and calling “lv_disp_set_rotation(NULL, LV_DISP_ROT_180) at “int main(void)” in RIOT/tests/pkg_lvgl/main.c”. However memory consumption is 87%, CPU load is 53% with just this test.
I think there should be a more convenient and economical way of turning display upside-down. I am trying to make this rotation inside of display controller (if possible) or in the driver or at least in the initialization but I couldn’t succeed any of them yet 
I am working…
With best regards,
Murat