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>

3 files changed, 45 insertions, 1 deletions

diff --git a/drivers/infiniband/hw/ipath/ipath_file_ops.c b/drivers/infiniband/hw/ipath/ipath_file_ops.c
index 17d4e970abd9..eab69dfdc28e 100644
--- a/drivers/infiniband/hw/ipath/ipath_file_ops.c
+++ b/drivers/infiniband/hw/ipath/ipath_file_ops.c
@@ -184,6 +184,29 @@ static int ipath_get_base_info(struct file *fp,
                 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;
diff --git a/drivers/infiniband/hw/ipath/ipath_init_chip.c b/drivers/infiniband/hw/ipath/ipath_init_chip.c
index 720ff4df84eb..1adafa97e082 100644
--- a/drivers/infiniband/hw/ipath/ipath_init_chip.c
+++ b/drivers/infiniband/hw/ipath/ipath_init_chip.c
@@ -341,6 +341,7 @@ static int init_chip_reset(struct ipath_devdata *dd)
 {
         u32 rtmp;
         int i;
+        unsigned long flags;
 
         /*
          * ensure chip does no sends or receives, tail updates, or
@@ -356,8 +357,13 @@ static int init_chip_reset(struct ipath_devdata *dd)
         ipath_write_kreg(dd, dd->ipath_kregs->kr_rcvctrl,
                 dd->ipath_rcvctrl);
 
+        spin_lock_irqsave(&dd->ipath_sendctrl_lock, flags);
+        dd->ipath_sendctrl = 0U; /* no sdma, etc */
         ipath_write_kreg(dd, dd->ipath_kregs->kr_sendctrl, dd->ipath_sendctrl);
-        ipath_write_kreg(dd, dd->ipath_kregs->kr_control, dd->ipath_control);
+        ipath_read_kreg64(dd, dd->ipath_kregs->kr_scratch);
+        spin_unlock_irqrestore(&dd->ipath_sendctrl_lock, flags);
+
+        ipath_write_kreg(dd, dd->ipath_kregs->kr_control, 0ULL);
 
         rtmp = ipath_read_kreg32(dd, dd->ipath_kregs->kr_rcvtidcnt);
         if (rtmp != dd->ipath_rcvtidcnt)
@@ -478,6 +484,14 @@ static void enable_chip(struct ipath_devdata *dd, int reinit)
         /* Enable PIO send, and update of PIOavail regs to memory. */
         dd->ipath_sendctrl = INFINIPATH_S_PIOENABLE |
                 INFINIPATH_S_PIOBUFAVAILUPD;
+
+        /*
+         * Set the PIO avail update threshold to host memory
+         * on chips that support it.
+         */
+        if (dd->ipath_pioupd_thresh)
+                dd->ipath_sendctrl |= dd->ipath_pioupd_thresh
+                        << INFINIPATH_S_UPDTHRESH_SHIFT;
         ipath_write_kreg(dd, dd->ipath_kregs->kr_sendctrl, dd->ipath_sendctrl);
         ipath_read_kreg64(dd, dd->ipath_kregs->kr_scratch);
         spin_unlock_irqrestore(&dd->ipath_sendctrl_lock, flags);
@@ -757,6 +771,12 @@ int ipath_init_chip(struct ipath_devdata *dd, int reinit)
         ipath_cdbg(VERBOSE, "%d PIO bufs for kernel out of %d total %u "
                    "each for %u user ports\n", kpiobufs,
                    piobufs, dd->ipath_pbufsport, uports);
+        if (dd->ipath_pioupd_thresh) {
+                if (dd->ipath_pbufsport < dd->ipath_pioupd_thresh)
+                        dd->ipath_pioupd_thresh = dd->ipath_pbufsport;
+                if (kpiobufs < dd->ipath_pioupd_thresh)
+                        dd->ipath_pioupd_thresh = kpiobufs;
+        }
 
         dd->ipath_f_early_init(dd);
         /*
diff --git a/drivers/infiniband/hw/ipath/ipath_kernel.h b/drivers/infiniband/hw/ipath/ipath_kernel.h
index 2447e85bf4f8..cef3296efb96 100644
--- a/drivers/infiniband/hw/ipath/ipath_kernel.h
+++ b/drivers/infiniband/hw/ipath/ipath_kernel.h
@@ -349,6 +349,7 @@ struct ipath_devdata {
         u32 ipath_lastrpkts;
         /* pio bufs allocated per port */
         u32 ipath_pbufsport;
+        u32 ipath_pioupd_thresh; /* update threshold, some chips */
         /*
          * number of ports configured as max; zero is set to number chip
          * supports, less gives more pio bufs/port, etc.