kinfo->spi_rcvhdr_base = ((u64) pd->subport_rcvhdr_base +
                        pd->port_rcvhdrq_size * slave) & MMAP64_MASK;
-               kinfo->spi_rcvhdr_tailaddr =
-                       (u64) pd->port_rcvhdrqtailaddr_phys & MMAP64_MASK;
+               kinfo->spi_rcvhdr_tailaddr = 0;
                kinfo->spi_rcv_egrbufs = ((u64) pd->subport_rcvegrbuf +
                        dd->ipath_rcvegrcnt * dd->ipath_rcvegrbufsize * slave) &
                        MMAP64_MASK;
        pd->port_subport_cnt = uinfo->spu_subport_cnt;
        pd->port_subport_id = uinfo->spu_subport_id;
        pd->active_slaves = 1;
+       set_bit(IPATH_PORT_MASTER_UNINIT, &pd->port_flag);
        goto bail;
 
 bail_rhdr:
                              const struct ipath_user_info *uinfo)
 {
        int ret;
-       struct ipath_portdata *pd;
+       struct ipath_portdata *pd = port_fp(fp);
        struct ipath_devdata *dd;
        u32 head32;
 
-       pd = port_fp(fp);
+       /* Subports don't need to initialize anything since master did it. */
+       if (subport_fp(fp)) {
+               ret = wait_event_interruptible(pd->port_wait,
+                       !test_bit(IPATH_PORT_MASTER_UNINIT, &pd->port_flag));
+               goto done;
+       }
+
        dd = pd->port_dd;
 
        if (uinfo->spu_rcvhdrsize) {
                         dd->ipath_rcvctrl & ~INFINIPATH_R_TAILUPD);
        ipath_write_kreg(dd, dd->ipath_kregs->kr_rcvctrl,
                         dd->ipath_rcvctrl);
+       /* Notify any waiting slaves */
+       if (pd->port_subport_cnt) {
+               clear_bit(IPATH_PORT_MASTER_UNINIT, &pd->port_flag);
+               wake_up(&pd->port_wait);
+       }
 done:
        return ret;
 }
 
 #define IPATH_PORT_WAITING_RCV   2
                /* waiting for a PIO buffer to be available */
 #define IPATH_PORT_WAITING_PIO   3
+               /* master has not finished initializing */
+#define IPATH_PORT_MASTER_UNINIT 4
 
 /* free up any allocated data at closes */
 void ipath_free_data(struct ipath_portdata *dd);