5 files changed, 30 insertions, 5 deletions

diff --git a/drivers/infiniband/hw/ipath/ipath_fs.c b/drivers/infiniband/hw/ipath/ipath_fs.c
index ebd5c7bd2cdb..40cf1bc90d74 100644
--- a/drivers/infiniband/hw/ipath/ipath_fs.c
+++ b/drivers/infiniband/hw/ipath/ipath_fs.c
@@ -257,9 +257,14 @@ static ssize_t atomic_port_info_read(struct file *file, char __user *buf,
                 /* Notimpl InitType (actually, an SMA decision) */
                 /* VLHighLimit is 0 (only one VL) */
                 ; /* VLArbitrationHighCap is 0 (only one VL) */
+        /*
+         * Note: the chips support a maximum MTU of 4096, but the driver
+         * hasn't implemented this feature yet, so set the maximum
+         * to 2048.
+         */
         portinfo[10] =  /* VLArbitrationLowCap is 0 (only one VL) */
                 /* InitTypeReply is SMA decision */
-                (5 << 16)       /* MTUCap 4096 */
+                (4 << 16)       /* MTUCap 2048 */
                 | (7 << 13)     /* VLStallCount */
                 | (0x1f << 8)   /* HOQLife */
                 | (1 << 4)
diff --git a/drivers/infiniband/hw/ipath/ipath_init_chip.c b/drivers/infiniband/hw/ipath/ipath_init_chip.c
index ee839346a3a4..bdfda6221744 100644
--- a/drivers/infiniband/hw/ipath/ipath_init_chip.c
+++ b/drivers/infiniband/hw/ipath/ipath_init_chip.c
@@ -310,7 +310,12 @@ static int init_chip_first(struct ipath_devdata *dd,
         val = ipath_read_kreg64(dd, dd->ipath_kregs->kr_sendpiosize);
         dd->ipath_piosize2k = val & ~0U;
         dd->ipath_piosize4k = val >> 32;
-        dd->ipath_ibmtu = 4096; /* default to largest legal MTU */
+        /*
+         * Note: the chips support a maximum MTU of 4096, but the driver
+         * hasn't implemented this feature yet, so set the initial value
+         * to 2048.
+         */
+        dd->ipath_ibmtu = 2048;
         val = ipath_read_kreg64(dd, dd->ipath_kregs->kr_sendpiobufcnt);
         dd->ipath_piobcnt2k = val & ~0U;
         dd->ipath_piobcnt4k = val >> 32;
diff --git a/drivers/infiniband/hw/ipath/ipath_mad.c b/drivers/infiniband/hw/ipath/ipath_mad.c
index 25908b02fbe5..2e9e161bfd0a 100644
--- a/drivers/infiniband/hw/ipath/ipath_mad.c
+++ b/drivers/infiniband/hw/ipath/ipath_mad.c
@@ -292,7 +292,12 @@ static int recv_subn_get_portinfo(struct ib_smp *smp,
         /* pip->vl_arb_high_cap; // only one VL */
         /* pip->vl_arb_low_cap; // only one VL */
         /* InitTypeReply = 0 */
-        pip->inittypereply_mtucap = IB_MTU_4096;
+        /*
+         * Note: the chips support a maximum MTU of 4096, but the driver
+         * hasn't implemented this feature yet, so set the maximum value
+         * to 2048.
+         */
+        pip->inittypereply_mtucap = IB_MTU_2048;
         // HCAs ignore VLStallCount and HOQLife
         /* pip->vlstallcnt_hoqlife; */
         pip->operationalvl_pei_peo_fpi_fpo = 0x10;      /* OVLs = 1 */
diff --git a/drivers/infiniband/hw/ipath/ipath_qp.c b/drivers/infiniband/hw/ipath/ipath_qp.c
index bfef08ecd342..9e07abba8aa7 100644
--- a/drivers/infiniband/hw/ipath/ipath_qp.c
+++ b/drivers/infiniband/hw/ipath/ipath_qp.c
@@ -507,8 +507,13 @@ int ipath_modify_qp(struct ib_qp *ibqp, struct ib_qp_attr *attr,
                     attr->port_num > ibqp->device->phys_port_cnt)
                         goto inval;
 
+        /*
+         * Note: the chips support a maximum MTU of 4096, but the driver
+         * hasn't implemented this feature yet, so don't allow Path MTU
+         * values greater than 2048.
+         */
         if (attr_mask & IB_QP_PATH_MTU)
-                if (attr->path_mtu > IB_MTU_4096)
+                if (attr->path_mtu > IB_MTU_2048)
                         goto inval;
 
         if (attr_mask & IB_QP_MAX_DEST_RD_ATOMIC)
diff --git a/drivers/infiniband/hw/ipath/ipath_verbs.c b/drivers/infiniband/hw/ipath/ipath_verbs.c
index bb70845279b8..980b64add321 100644
--- a/drivers/infiniband/hw/ipath/ipath_verbs.c
+++ b/drivers/infiniband/hw/ipath/ipath_verbs.c
@@ -1051,7 +1051,12 @@ static int ipath_query_port(struct ib_device *ibdev,
         props->max_vl_num = 1;          /* VLCap = VL0 */
         props->init_type_reply = 0;
 
-        props->max_mtu = IB_MTU_4096;
+        /*
+         * Note: the chips support a maximum MTU of 4096, but the driver
+         * hasn't implemented this feature yet, so set the maximum value
+         * to 2048.
+         */
+        props->max_mtu = IB_MTU_2048;
         switch (dev->dd->ipath_ibmtu) {
         case 4096:
                 mtu = IB_MTU_4096;