USBA_FORCE_STALL
usba_ep_writel(ep, SET_STA, USBA_FORCE_STALL);
if (usba_ep_readl(ep, STA) & USBA_FORCE_STALL)
usba_ep_writel(target, CLR_STA, USBA_FORCE_STALL);
usba_ep_writel(target, SET_STA, USBA_FORCE_STALL);
usba_ep_writel(ep, SET_STA, USBA_FORCE_STALL);
USBA_FORCE_STALL | USBA_TOGGLE_CLR);