IVTV_F_I_EV_VSYNC_ENABLED
clear_bit(IVTV_F_I_EV_VSYNC_ENABLED, &itv->i_flags);
set_bit(IVTV_F_I_EV_VSYNC_ENABLED, &itv->i_flags);
if (test_bit(IVTV_F_I_EV_VSYNC_ENABLED, &itv->i_flags)) {