LVGL Filesystem

Hello! I am trying to register an SD card into the LVGL’s filesystem.
The problem that when i try to set an image i get lv_fs_open: Can't open file (C:image.bin): unknown driver letter (in lv_fs.c line #68).

Here is my code:

Filesystem init

bool LVFileSystem::init(char letter) {
    sdSPI.begin(
        PIN_SD_CLK,
        PIN_SD_MISO,
        PIN_SD_MOSI
    );
    if (!SD.begin(PIN_SD_CS, sdSPI)) return false;

    lv_fs_drv_t drv;
    lv_fs_drv_init(&drv);

    drv.letter = letter;
    drv.cache_size = 0;
    drv.ready_cb = sd_ready_cb;
    drv.open_cb = sd_open_cb;
    drv.close_cb = sd_close_cb;
    drv.read_cb = sd_read_cb;
    drv.write_cb = sd_write_cb;
    drv.seek_cb = sd_seek_cb;
    drv.tell_cb = sd_tell_cb;
    drv.dir_open_cb = nullptr;
    drv.dir_read_cb = nullptr;
    drv.dir_close_cb = nullptr;

    lv_fs_drv_register(&drv);
    return isInitialized = true;
}

Usage

LVFileSystem::init('C');
lv_img_set_src(image, "C:image.bin");

I also tried to specify the path differently (like C:/ C:\). I will appreciate any help, so thanks in advance!

SOLVED

So, i added _lv_fs_init() call and everything started to work as it needed.