net/bnxt: fix doorbell barrier location

Simplify some doorbell functions now that rte_cio_wmb() has been
eliminated and rte_io_wmb() is equivalent for Arm.

Fix a performance degradation on x86 platforms caused by a
previous Arm performance fix by moving the compiler barrier
closer to the I/O write.

Fixes: f0f5d844d138 ("eal: remove deprecated coherent IO memory barriers")
Fixes: bfc1d45875e2 ("net/bnxt: fix performance for Arm")
Cc: stable@dpdk.org
Signed-off-by: Lance Richardson <lance.richardson@broadcom.com>
Signed-off-by: Ajit Khaparde <ajit.khaparde@broadcom.com>

diff --git a/drivers/net/bnxt/bnxt_ring.h b/drivers/net/bnxt/bnxt_ring.h
index 3d81f61..0a4685d 100644 (file)
--- a/drivers/net/bnxt/bnxt_ring.h
+++ b/drivers/net/bnxt/bnxt_ring.h
@@ -82,12 +82,10 @@ void bnxt_free_rxtx_nq_ring(struct bnxt *bp);
 
 static inline void bnxt_db_write(struct bnxt_db_info *db, uint32_t idx)
 {
-       rte_io_wmb();
-
        if (db->db_64)
-               rte_write64_relaxed(db->db_key64 | idx, db->doorbell);
+               rte_write64(db->db_key64 | idx, db->doorbell);
        else
-               rte_write32_relaxed(db->db_key32 | idx, db->doorbell);
+               rte_write32(db->db_key32 | idx, db->doorbell);
 }
 
 /* Ring an NQ doorbell and disable interrupts for the ring. */
@@ -96,10 +94,9 @@ static inline void bnxt_db_nq(struct bnxt_cp_ring_info *cpr)
        if (unlikely(!cpr->cp_db.db_64))
                return;
 
-       rte_io_wmb();
-       rte_write64_relaxed(cpr->cp_db.db_key64 | DBR_TYPE_NQ |
-                           RING_CMP(cpr->cp_ring_struct, cpr->cp_raw_cons),
-                           cpr->cp_db.doorbell);
+       rte_write64(cpr->cp_db.db_key64 | DBR_TYPE_NQ |
+                   RING_CMP(cpr->cp_ring_struct, cpr->cp_raw_cons),
+                   cpr->cp_db.doorbell);
 }
 
 /* Ring an NQ doorbell and enable interrupts for the ring. */
@@ -108,10 +105,9 @@ static inline void bnxt_db_nq_arm(struct bnxt_cp_ring_info *cpr)
        if (unlikely(!cpr->cp_db.db_64))
                return;
 
-       rte_io_wmb();
-       rte_write64_relaxed(cpr->cp_db.db_key64 | DBR_TYPE_NQ_ARM |
-                           RING_CMP(cpr->cp_ring_struct, cpr->cp_raw_cons),
-                           cpr->cp_db.doorbell);
+       rte_write64(cpr->cp_db.db_key64 | DBR_TYPE_NQ_ARM |
+                   RING_CMP(cpr->cp_ring_struct, cpr->cp_raw_cons),
+                   cpr->cp_db.doorbell);
 }
 
 static inline void bnxt_db_cq(struct bnxt_cp_ring_info *cpr)
@@ -119,11 +115,18 @@ static inline void bnxt_db_cq(struct bnxt_cp_ring_info *cpr)
        struct bnxt_db_info *db = &cpr->cp_db;
        uint32_t idx = RING_CMP(cpr->cp_ring_struct, cpr->cp_raw_cons);
 
-       rte_compiler_barrier();
-       if (db->db_64)
-               rte_write64_relaxed(db->db_key64 | idx, db->doorbell);
-       else
-               B_CP_DIS_DB(cpr, cpr->cp_raw_cons);
+       if (db->db_64) {
+               uint64_t key_idx = db->db_key64 | idx;
+               void *doorbell = db->doorbell;
+
+               rte_compiler_barrier();
+               rte_write64_relaxed(key_idx, doorbell);
+       } else {
+               uint32_t cp_raw_cons = cpr->cp_raw_cons;
+
+               rte_compiler_barrier();
+               B_CP_DIS_DB(cpr, cp_raw_cons);
+       }
 }
 
 #endif