MUSB_CSR0_P_SENDSTALL
csr |= MUSB_CSR0_P_SENDSTALL;
csr = MUSB_CSR0_P_SVDRXPKTRDY | MUSB_CSR0_P_SENDSTALL;
musb->ackpend |= MUSB_CSR0_P_SENDSTALL;
musb_writew(regs, MUSB_CSR0, MUSB_CSR0_P_SENDSTALL);