qed: Protect the doorbell BAR with the write barriers.

SPQ doorbell is currently protected with the compilation barrier. Under the
stress scenarios, we may get into a state where (due to the weak ordering)
several ramrod doorbells were written to the BAR with an out-of-order
producer values. Need to change the barrier type to a write barrier to make
sure that the write buffer is flushed after each doorbell.

Signed-off-by: Sudarsana Reddy Kalluru <sudarsana.kalluru@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 7 deletions

diff --git a/drivers/net/ethernet/qlogic/qed/qed_spq.c b/drivers/net/ethernet/qlogic/qed/qed_spq.c
index 67d9893774d8..b122f6013b6c 100644
--- a/drivers/net/ethernet/qlogic/qed/qed_spq.c
+++ b/drivers/net/ethernet/qlogic/qed/qed_spq.c
@@ -213,19 +213,15 @@ static int qed_spq_hw_post(struct qed_hwfn *p_hwfn,
         SET_FIELD(db.params, CORE_DB_DATA_AGG_VAL_SEL,
                   DQ_XCM_CORE_SPQ_PROD_CMD);
         db.agg_flags = DQ_XCM_CORE_DQ_CF_CMD;
-
-        /* validate producer is up to-date */
-        rmb();
-
         db.spq_prod = cpu_to_le16(qed_chain_get_prod_idx(p_chain));
 
-        /* do not reorder */
-        barrier();
+        /* make sure the SPQE is updated before the doorbell */
+        wmb();
 
         DOORBELL(p_hwfn, qed_db_addr(p_spq->cid, DQ_DEMS_LEGACY), *(u32 *)&db);
 
         /* make sure doorbell is rang */
-        mmiowb();
+        wmb();
 
         DP_VERBOSE(p_hwfn, QED_MSG_SPQ,
                    "Doorbelled [0x%08x, CID 0x%08x] with Flags: %02x agg_params: %02x, prod: %04x\n",