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