liquidio: Prioritize control messages

During heavy tx traffic, control messages (sent by liquidio driver to NIC
firmware) sometimes do not get processed in a timely manner.  Reason is:
the low-level metadata of control messages and that of egress network
packets indicate that they have the same priority.

Fix it by setting a higher priority for control messages through the new
ctrl_qpg field in the oct_txpciq struct.  It is the NIC firmware that does
the actual setting of priority by writing to the new ctrl_qpg field; the
host driver treats that value as opaque and just assigns it to pki_ih3->qpg
Signed-off-by: NIntiyaz Basha <intiyaz.basha@cavium.com>
Signed-off-by: NFelix Manlunas <felix.manlunas@cavium.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/cavium/liquidio/liquidio_common.h

@@ -712,9 +712,13 @@ union oct_txpciq {
 		u64 pkind:6;
 		u64 use_qpg:1;
 		u64 qpg:11;
-		u64 reserved:30;
+		u64 reserved0:10;
+		u64 ctrl_qpg:11;
+		u64 reserved:9;
 #else
-		u64 reserved:30;
+		u64 reserved:9;
+		u64 ctrl_qpg:11;
+		u64 reserved0:10;
 		u64 qpg:11;
 		u64 use_qpg:1;
 		u64 pkind:6;

drivers/net/ethernet/cavium/liquidio/request_manager.c

@@ -628,7 +628,8 @@ octeon_prepare_soft_command(struct octeon_device *oct,
 		pki_ih3->tag     = LIO_CONTROL;
 		pki_ih3->tagtype = ATOMIC_TAG;
 		pki_ih3->qpg         =
-			oct->instr_queue[sc->iq_no]->txpciq.s.qpg;
+			oct->instr_queue[sc->iq_no]->txpciq.s.ctrl_qpg;
+
 		pki_ih3->pm          = 0x7;
 		pki_ih3->sl          = 8;