common/cnxk: enable completion queue overflow errata

An issue exists on some HW revisions whereby if a CQ overflows
NIX may have undefined behavior, e.g. free incorrect buffers.
Implementing a workaround for this known HW issue.

Signed-off-by: Harman Kalra <hkalra@marvell.com>
Acked-by: Jerin Jacob <jerinj@marvell.com>

diff --git a/drivers/common/cnxk/roc_nix_priv.h b/drivers/common/cnxk/roc_nix_priv.h
index b67f648..b573879 100644 (file)
--- a/drivers/common/cnxk/roc_nix_priv.h
+++ b/drivers/common/cnxk/roc_nix_priv.h
@@ -17,7 +17,8 @@
 
 /* Apply BP/DROP when CQ is 95% full */
 #define NIX_CQ_THRESH_LEVEL    (5 * 256 / 100)
-#define NIX_RQ_AURA_THRESH(x)  (((x) * 95) / 100)
+#define NIX_CQ_FULL_ERRATA_SKID (1024ull * 256)
+#define NIX_RQ_AURA_THRESH(x)  (((x)*95) / 100)
 
 /* IRQ triggered when NIX_LF_CINTX_CNT[QCOUNT] crosses this value */
 #define CQ_CQE_THRESH_DEFAULT  0x1ULL

diff --git a/drivers/common/cnxk/roc_nix_queue.c b/drivers/common/cnxk/roc_nix_queue.c
index 76e439e..d7c4844 100644 (file)
--- a/drivers/common/cnxk/roc_nix_queue.c
+++ b/drivers/common/cnxk/roc_nix_queue.c
@@ -2,6 +2,8 @@
  * Copyright(C) 2021 Marvell.
  */
 
+#include <math.h>
+
 #include "roc_api.h"
 #include "roc_priv.h"
 
@@ -435,7 +437,6 @@ roc_nix_cq_init(struct roc_nix *roc_nix, struct roc_nix_cq *cq)
        cq->status = (int64_t *)(nix->base + NIX_LF_CQ_OP_STATUS);
        cq->wdata = (uint64_t)cq->qid << 32;
        cq->roc_nix = roc_nix;
-       cq->drop_thresh = NIX_CQ_THRESH_LEVEL;
 
        /* CQE of W16 */
        desc_sz = cq->nb_desc * NIX_CQ_ENTRY_SZ;
@@ -476,8 +477,19 @@ roc_nix_cq_init(struct roc_nix *roc_nix, struct roc_nix_cq *cq)
        /* Map CQ0 [RQ0] to CINT0 and so on till max 64 irqs */
        cq_ctx->cint_idx = cq->qid;
 
-       cq_ctx->drop = cq->drop_thresh;
-       cq_ctx->drop_ena = 1;
+       if (roc_model_is_cn96_a0() || roc_model_is_cn95_a0()) {
+               const float rx_cq_skid = NIX_CQ_FULL_ERRATA_SKID;
+               uint16_t min_rx_drop;
+
+               min_rx_drop = ceil(rx_cq_skid / (float)cq->nb_desc);
+               cq_ctx->drop = min_rx_drop;
+               cq_ctx->drop_ena = 1;
+               cq->drop_thresh = min_rx_drop;
+       } else {
+               cq->drop_thresh = NIX_CQ_THRESH_LEVEL;
+               cq_ctx->drop = cq->drop_thresh;
+               cq_ctx->drop_ena = 1;
+       }
 
        /* TX pause frames enable flow ctrl on RX side */
        if (nix->tx_pause) {