net/mlx5e: XDP, Replace boolean doorbell indication with segment pointer

Instead of calculating the control segment to be used upon an
XDP xmit doorbell, save it in SQ structure.
Nullify when no pending doorbell.
Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>

drivers/net/ethernet/mellanox/mlx5/core/en.h

@@ -413,7 +413,7 @@ struct mlx5e_xdpsq {
 
 	/* dirtied @xmit */
 	u16                        pc ____cacheline_aligned_in_smp;
-	bool                       doorbell;
+	struct mlx5_wqe_ctrl_seg   *doorbell_cseg;
 
 	struct mlx5e_cq            cq;
 

drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c

@@ -126,11 +126,8 @@ bool mlx5e_xmit_xdp_frame(struct mlx5e_xdpsq *sq, struct mlx5e_xdp_info *xdpi)
 	}
 
 	if (unlikely(!mlx5e_wqc_has_room_for(wq, sq->cc, sq->pc, 1))) {
-		if (sq->doorbell) {
 		/* SQ is full, ring doorbell */
 		mlx5e_xmit_xdp_doorbell(sq);
-			sq->doorbell = false;
-		}
 		stats->full++;
 		return false;
 	}
@@ -158,7 +155,7 @@ bool mlx5e_xmit_xdp_frame(struct mlx5e_xdpsq *sq, struct mlx5e_xdp_info *xdpi)
 	sq->db.xdpi[pi] = *xdpi;
 	sq->pc++;
 
-	sq->doorbell = true;
+	sq->doorbell_cseg = cseg;
 
 	stats->xmit++;
 	return true;
@@ -309,10 +306,7 @@ void mlx5e_xdp_rx_poll_complete(struct mlx5e_rq *rq)
 {
 	struct mlx5e_xdpsq *xdpsq = &rq->xdpsq;
 
-	if (xdpsq->doorbell) {
 	mlx5e_xmit_xdp_doorbell(xdpsq);
-		xdpsq->doorbell = false;
-	}
 
 	if (xdpsq->redirect_flush) {
 		xdp_do_flush_map();

drivers/net/ethernet/mellanox/mlx5/core/en/xdp.h

@@ -51,13 +51,10 @@ int mlx5e_xdp_xmit(struct net_device *dev, int n, struct xdp_frame **frames,
 
 static inline void mlx5e_xmit_xdp_doorbell(struct mlx5e_xdpsq *sq)
 {
-	struct mlx5_wq_cyc *wq = &sq->wq;
-	struct mlx5e_tx_wqe *wqe;
-	u16 pi = mlx5_wq_cyc_ctr2ix(wq, sq->pc - 1); /* last pi */
-
-	wqe  = mlx5_wq_cyc_get_wqe(wq, pi);
-
-	mlx5e_notify_hw(wq, sq->pc, sq->uar_map, &wqe->ctrl);
+	if (sq->doorbell_cseg) {
+		mlx5e_notify_hw(&sq->wq, sq->pc, sq->uar_map, sq->doorbell_cseg);
+		sq->doorbell_cseg = NULL;
+	}
 }
 
 #endif