AST_VHUB_EPn_MAX_PACKET
AST_VHUB_EPn_MAX_PACKET +
AST_VHUB_EPn_MAX_PACKET +
ep->epn.descs = ep->buf + AST_VHUB_EPn_MAX_PACKET;
ep->epn.descs_dma = ep->buf_dma + AST_VHUB_EPn_MAX_PACKET;
usb_ep_set_maxpacket_limit(&ep->ep, AST_VHUB_EPn_MAX_PACKET);