IB/ipath: Enable reduced PIO update for HCAs that support it.
Newer HCAs have a threshold counter to reduce the number of DMAs the
chip makes to update the PIO buffer availability status bits. This
patch enables the feature.
Signed-off-by: Dave Olson <dave.olson@qlogic.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
diff --git a/drivers/infiniband/hw/ipath/ipath_file_ops.c b/drivers/infiniband/hw/ipath/ipath_file_ops.c
index 17d4e97..eab69df 100644
--- a/drivers/infiniband/hw/ipath/ipath_file_ops.c
+++ b/drivers/infiniband/hw/ipath/ipath_file_ops.c
@@ -184,6 +184,29 @@
kinfo->spi_piobufbase = (u64) pd->port_piobufs +
dd->ipath_palign * kinfo->spi_piocnt * slave;
}
+
+ /*
+ * Set the PIO avail update threshold to no larger
+ * than the number of buffers per process. Note that
+ * we decrease it here, but won't ever increase it.
+ */
+ if (dd->ipath_pioupd_thresh &&
+ kinfo->spi_piocnt < dd->ipath_pioupd_thresh) {
+ unsigned long flags;
+
+ dd->ipath_pioupd_thresh = kinfo->spi_piocnt;
+ ipath_dbg("Decreased pio update threshold to %u\n",
+ dd->ipath_pioupd_thresh);
+ spin_lock_irqsave(&dd->ipath_sendctrl_lock, flags);
+ dd->ipath_sendctrl &= ~(INFINIPATH_S_UPDTHRESH_MASK
+ << INFINIPATH_S_UPDTHRESH_SHIFT);
+ dd->ipath_sendctrl |= dd->ipath_pioupd_thresh
+ << INFINIPATH_S_UPDTHRESH_SHIFT;
+ ipath_write_kreg(dd, dd->ipath_kregs->kr_sendctrl,
+ dd->ipath_sendctrl);
+ spin_unlock_irqrestore(&dd->ipath_sendctrl_lock, flags);
+ }
+
if (shared) {
kinfo->spi_port_uregbase = (u64) dd->ipath_uregbase +
dd->ipath_ureg_align * pd->port_port;