octeontx2-pf: Use hardware register for CQE count

Current driver uses software CQ head pointer to poll on CQE
header in memory to determine if CQE is valid. Software needs
to make sure, that the reads of the CQE do not get re-ordered
so much that it ends up with an inconsistent view of the CQE.
To ensure that DMB barrier after read to first CQE cacheline
and before reading of the rest of the CQE is needed.
But having barrier for every CQE read will impact the performance,
instead use hardware CQ head and tail pointers to find the
valid number of CQEs.

Signed-off-by: Geetha sowjanya <gakula@marvell.com>
Signed-off-by: Sunil Kovvuri Goutham <sgoutham@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 62 insertions, 7 deletions

diff --git a/drivers/net/ethernet/marvell/octeontx2/nic/otx2_txrx.c b/drivers/net/ethernet/marvell/octeontx2/nic/otx2_txrx.c
index f42b1d4e0c67..3f3ec8ffc4dd 100644
--- a/drivers/net/ethernet/marvell/octeontx2/nic/otx2_txrx.c
+++ b/drivers/net/ethernet/marvell/octeontx2/nic/otx2_txrx.c
@@ -18,6 +18,31 @@
 
 #define CQE_ADDR(CQ, idx) ((CQ)->cqe_base + ((CQ)->cqe_size * (idx)))
 
+static int otx2_nix_cq_op_status(struct otx2_nic *pfvf,
+				 struct otx2_cq_queue *cq)
+{
+	u64 incr = (u64)(cq->cq_idx) << 32;
+	u64 status;
+
+	status = otx2_atomic64_fetch_add(incr, pfvf->cq_op_addr);
+
+	if (unlikely(status & BIT_ULL(CQ_OP_STAT_OP_ERR) ||
+		     status & BIT_ULL(CQ_OP_STAT_CQ_ERR))) {
+		dev_err(pfvf->dev, "CQ stopped due to error");
+		return -EINVAL;
+	}
+
+	cq->cq_tail = status & 0xFFFFF;
+	cq->cq_head = (status >> 20) & 0xFFFFF;
+	if (cq->cq_tail < cq->cq_head)
+		cq->pend_cqe = (cq->cqe_cnt - cq->cq_head) +
+				cq->cq_tail;
+	else
+		cq->pend_cqe = cq->cq_tail - cq->cq_head;
+
+	return 0;
+}
+
 static struct nix_cqe_hdr_s *otx2_get_next_cqe(struct otx2_cq_queue *cq)
 {
 	struct nix_cqe_hdr_s *cqe_hdr;
@@ -318,7 +343,14 @@ static int otx2_rx_napi_handler(struct otx2_nic *pfvf,
 	struct nix_cqe_rx_s *cqe;
 	int processed_cqe = 0;
 
-	while (likely(processed_cqe < budget)) {
+	if (cq->pend_cqe >= budget)
+		goto process_cqe;
+
+	if (otx2_nix_cq_op_status(pfvf, cq) || !cq->pend_cqe)
+		return 0;
+
+process_cqe:
+	while (likely(processed_cqe < budget) && cq->pend_cqe) {
 		cqe = (struct nix_cqe_rx_s *)CQE_ADDR(cq, cq->cq_head);
 		if (cqe->hdr.cqe_type == NIX_XQE_TYPE_INVALID ||
 		    !cqe->sg.seg_addr) {
@@ -334,6 +366,7 @@ static int otx2_rx_napi_handler(struct otx2_nic *pfvf,
 		cqe->hdr.cqe_type = NIX_XQE_TYPE_INVALID;
 		cqe->sg.seg_addr = 0x00;
 		processed_cqe++;
+		cq->pend_cqe--;
 	}
 
 	/* Free CQEs to HW */
@@ -368,7 +401,14 @@ static int otx2_tx_napi_handler(struct otx2_nic *pfvf,
 	struct nix_cqe_tx_s *cqe;
 	int processed_cqe = 0;
 
-	while (likely(processed_cqe < budget)) {
+	if (cq->pend_cqe >= budget)
+		goto process_cqe;
+
+	if (otx2_nix_cq_op_status(pfvf, cq) || !cq->pend_cqe)
+		return 0;
+
+process_cqe:
+	while (likely(processed_cqe < budget) && cq->pend_cqe) {
 		cqe = (struct nix_cqe_tx_s *)otx2_get_next_cqe(cq);
 		if (unlikely(!cqe)) {
 			if (!processed_cqe)
@@ -380,6 +420,7 @@ static int otx2_tx_napi_handler(struct otx2_nic *pfvf,
 
 		cqe->hdr.cqe_type = NIX_XQE_TYPE_INVALID;
 		processed_cqe++;
+		cq->pend_cqe--;
 	}
 
 	/* Free CQEs to HW */
@@ -936,10 +977,16 @@ void otx2_cleanup_rx_cqes(struct otx2_nic *pfvf, struct otx2_cq_queue *cq)
 	int processed_cqe = 0;
 	u64 iova, pa;
 
-	while ((cqe = (struct nix_cqe_rx_s *)otx2_get_next_cqe(cq))) {
-		if (!cqe->sg.subdc)
-			continue;
+	if (otx2_nix_cq_op_status(pfvf, cq) || !cq->pend_cqe)
+		return;
+
+	while (cq->pend_cqe) {
+		cqe = (struct nix_cqe_rx_s *)otx2_get_next_cqe(cq);
 		processed_cqe++;
+		cq->pend_cqe--;
+
+		if (!cqe)
+			continue;
 		if (cqe->sg.segs > 1) {
 			otx2_free_rcv_seg(pfvf, cqe, cq->cq_idx);
 			continue;
@@ -965,7 +1012,16 @@ void otx2_cleanup_tx_cqes(struct otx2_nic *pfvf, struct otx2_cq_queue *cq)
 
 	sq = &pfvf->qset.sq[cq->cint_idx];
 
-	while ((cqe = (struct nix_cqe_tx_s *)otx2_get_next_cqe(cq))) {
+	if (otx2_nix_cq_op_status(pfvf, cq) || !cq->pend_cqe)
+		return;
+
+	while (cq->pend_cqe) {
+		cqe = (struct nix_cqe_tx_s *)otx2_get_next_cqe(cq);
+		processed_cqe++;
+		cq->pend_cqe--;
+
+		if (!cqe)
+			continue;
 		sg = &sq->sg[cqe->comp.sqe_id];
 		skb = (struct sk_buff *)sg->skb;
 		if (skb) {
@@ -973,7 +1029,6 @@ void otx2_cleanup_tx_cqes(struct otx2_nic *pfvf, struct otx2_cq_queue *cq)
 			dev_kfree_skb_any(skb);
 			sg->skb = (u64)NULL;
 		}
-		processed_cqe++;
 	}
 
 	/* Free CQEs to HW */