It didn't cause big issues when VT-d was disabled. But in VT-d enabled platform, lack of EhcFreeUrb call caused the DMA data was not moved back to user's buffer. It caused the correct data cannot be got through sync interrupt transfer. Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Ruiyu Ni <ruiyu.ni@intel.com> Reviewed-by: Star Zeng <star.zeng@intel.com>