IB/ipath: Fix maximum MTU reporting

Although our chip supports 4K MTUs, our driver doesn't yet support
this feature, so limit the maximum MTU to 2K until we get support for
4K MTUs implemented.

Signed-off-by: Robert Walsh <robert.walsh@qlogic.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

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 ebd5c7bd2cd..40cf1bc90d7 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 ee839346a3a..bdfda622174 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 25908b02fbe..2e9e161bfd0 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 bfef08ecd34..9e07abba8aa 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 bb70845279b..980b64add32 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;