1 files changed, 22 insertions, 11 deletions

diff --git a/drivers/infiniband/hw/ipath/ipath_driver.c b/drivers/infiniband/hw/ipath/ipath_driver.c
index eb745234d8c3..e2b0bc8ebaf4 100644
--- a/drivers/infiniband/hw/ipath/ipath_driver.c
+++ b/drivers/infiniband/hw/ipath/ipath_driver.c
@@ -870,7 +870,7 @@ void ipath_kreceive(struct ipath_devdata *dd)
         const u32 maxcnt = dd->ipath_rcvhdrcnt * rsize; /* words */
         u32 etail = -1, l, hdrqtail;
         struct ips_message_header *hdr;
-        u32 eflags, i, etype, tlen, pkttot = 0;
+        u32 eflags, i, etype, tlen, pkttot = 0, updegr=0;
         static u64 totcalls;    /* stats, may eventually remove */
         char emsg[128];
 
@@ -884,14 +884,14 @@ void ipath_kreceive(struct ipath_devdata *dd)
         if (test_and_set_bit(0, &dd->ipath_rcv_pending))
                 goto bail;
 
-        if (dd->ipath_port0head ==
-            (u32)le64_to_cpu(*dd->ipath_hdrqtailptr))
+        l = dd->ipath_port0head;
+        if (l == (u32)le64_to_cpu(*dd->ipath_hdrqtailptr))
                 goto done;
 
         /* read only once at start for performance */
         hdrqtail = (u32)le64_to_cpu(*dd->ipath_hdrqtailptr);
 
-        for (i = 0, l = dd->ipath_port0head; l != hdrqtail; i++) {
+        for (i = 0; l != hdrqtail; i++) {
                 u32 qp;
                 u8 *bthbytes;
 
@@ -1002,15 +1002,26 @@ void ipath_kreceive(struct ipath_devdata *dd)
                 l += rsize;
                 if (l >= maxcnt)
                         l = 0;
+                if (etype != RCVHQ_RCV_TYPE_EXPECTED)
+                    updegr = 1;
                 /*
-                 * update for each packet, to help prevent overflows if we
-                 * have lots of packets.
+                 * update head regs on last packet, and every 16 packets.
+                 * Reduce bus traffic, while still trying to prevent
+                 * rcvhdrq overflows, for when the queue is nearly full
                  */
-                (void)ipath_write_ureg(dd, ur_rcvhdrhead,
-                                       dd->ipath_rhdrhead_intr_off | l, 0);
-                if (etype != RCVHQ_RCV_TYPE_EXPECTED)
-                        (void)ipath_write_ureg(dd, ur_rcvegrindexhead,
-                                               etail, 0);
+                if (l == hdrqtail || (i && !(i&0xf))) {
+                        u64 lval;
+                        if (l == hdrqtail) /* want interrupt only on last */
+                                lval = dd->ipath_rhdrhead_intr_off | l;
+                        else
+                                lval = l;
+                        (void)ipath_write_ureg(dd, ur_rcvhdrhead, lval, 0);
+                        if (updegr) {
+                                (void)ipath_write_ureg(dd, ur_rcvegrindexhead,
+                                                       etail, 0);
+                                updegr = 0;
+                        }
+                }
         }
 
         pkttot += i;