AHCI_P_IS
AHCI_WRITE(sc, AHCI_P_IS(chp->ch_channel), 0xffffffff);
AHCI_WRITE(sc, AHCI_P_IS(chp->ch_channel), 0xffffffff);
AHCI_WRITE(sc, AHCI_P_IS(chp->ch_channel), 0xffffffff);
is = AHCI_READ(sc, AHCI_P_IS(chp->ch_channel));
AHCI_WRITE(sc, AHCI_P_IS(chp->ch_channel), is);
is = AHCI_READ(sc, AHCI_P_IS(chp->ch_channel));
AHCI_WRITE(sc, AHCI_P_IS(chp->ch_channel), 0xffffffff);
AHCI_WRITE(sc, AHCI_P_IS(chp->ch_channel), 0xffffffff);