net/mlx5: remove CQE padding device argument

[ upstream commit 4a7f979 ]

The data-path code doesn't take care on 'rxq_cqe_pad_en' and use padded
CQE for any case when the system cache-line size is 128B.

This makes the argument redundant.

Remove it.

Fixes: bc91e8d ("net/mlx5: add 128B padding of Rx completion entry")

Signed-off-by: Michael Baum <michaelba@nvidia.com>
Acked-by: Matan Azrad <matan@nvidia.com>

doc/guides/nics/mlx5.rst

@@ -448,24 +448,6 @@ Driver options
   - POWER9 and ARMv8 with ConnectX-4 Lx, ConnectX-5, ConnectX-6, ConnectX-6 Dx,
     ConnectX-6 Lx, BlueField and BlueField-2.
 
-- ``rxq_cqe_pad_en`` parameter [int]
-
-  A nonzero value enables 128B padding of CQE on RX side. The size of CQE
-  is aligned with the size of a cacheline of the core. If cacheline size is
-  128B, the CQE size is configured to be 128B even though the device writes
-  only 64B data on the cacheline. This is to avoid unnecessary cache
-  invalidation by device's two consecutive writes on to one cacheline.
-  However in some architecture, it is more beneficial to update entire
-  cacheline with padding the rest 64B rather than striding because
-  read-modify-write could drop performance a lot. On the other hand,
-  writing extra data will consume more PCIe bandwidth and could also drop
-  the maximum throughput. It is recommended to empirically set this
-  parameter. Disabled by default.
-
-  Supported on:
-
-  - CPU having 128B cacheline with ConnectX-5 and BlueField.
-
 - ``rxq_pkt_pad_en`` parameter [int]
 
   A nonzero value enables padding Rx packet to the size of cacheline on PCI

drivers/net/mlx5/linux/mlx5_os.c

@@ -671,7 +671,6 @@ mlx5_dev_spawn(struct rte_device *dpdk_dev,
 	unsigned int hw_padding = 0;
 	unsigned int mps;
 	unsigned int cqe_comp;
-	unsigned int cqe_pad = 0;
 	unsigned int tunnel_en = 0;
 	unsigned int mpls_en = 0;
 	unsigned int swp = 0;
@@ -869,11 +868,6 @@ mlx5_dev_spawn(struct rte_device *dpdk_dev,
 	else
 		cqe_comp = 1;
 	config->cqe_comp = cqe_comp;
-#ifdef HAVE_IBV_MLX5_MOD_CQE_128B_PAD
-	/* Whether device supports 128B Rx CQE padding. */
-	cqe_pad = RTE_CACHE_LINE_SIZE == 128 &&
-		  (dv_attr.flags & MLX5DV_CONTEXT_FLAGS_CQE_128B_PAD);
-#endif
 #ifdef HAVE_IBV_DEVICE_TUNNEL_SUPPORT
 	if (dv_attr.comp_mask & MLX5DV_CONTEXT_MASK_TUNNEL_OFFLOADS) {
 		tunnel_en = ((dv_attr.tunnel_offloads_caps &
@@ -1110,12 +1104,6 @@ mlx5_dev_spawn(struct rte_device *dpdk_dev,
 		DRV_LOG(WARNING, "Rx CQE compression isn't supported");
 		config->cqe_comp = 0;
 	}
-	if (config->cqe_pad && !cqe_pad) {
-		DRV_LOG(WARNING, "Rx CQE padding isn't supported");
-		config->cqe_pad = 0;
-	} else if (config->cqe_pad) {
-		DRV_LOG(INFO, "Rx CQE padding is enabled");
-	}
 	if (config->devx) {
 		err = mlx5_devx_cmd_query_hca_attr(sh->ctx, &config->hca_attr);
 		if (err) {

drivers/net/mlx5/linux/mlx5_verbs.c

@@ -234,7 +234,7 @@ mlx5_rxq_ibv_cq_create(struct rte_eth_dev *dev, uint16_t idx)
 			dev->data->port_id);
 	}
 #ifdef HAVE_IBV_MLX5_MOD_CQE_128B_PAD
-	if (priv->config.cqe_pad) {
+	if (RTE_CACHE_LINE_SIZE == 128) {
 		cq_attr.mlx5.comp_mask |= MLX5DV_CQ_INIT_ATTR_MASK_FLAGS;
 		cq_attr.mlx5.flags |= MLX5DV_CQ_INIT_ATTR_FLAGS_CQE_PAD;
 	}

drivers/net/mlx5/mlx5.c

@@ -43,9 +43,6 @@
 /* Device parameter to enable RX completion queue compression. */
 #define MLX5_RXQ_CQE_COMP_EN "rxq_cqe_comp_en"
 
-/* Device parameter to enable RX completion entry padding to 128B. */
-#define MLX5_RXQ_CQE_PAD_EN "rxq_cqe_pad_en"
-
 /* Device parameter to enable padding Rx packet to cacheline size. */
 #define MLX5_RXQ_PKT_PAD_EN "rxq_pkt_pad_en"
 
@@ -1623,8 +1620,6 @@ mlx5_args_check(const char *key, const char *val, void *opaque)
 		}
 		config->cqe_comp = !!tmp;
 		config->cqe_comp_fmt = tmp;
-	} else if (strcmp(MLX5_RXQ_CQE_PAD_EN, key) == 0) {
-		config->cqe_pad = !!tmp;
 	} else if (strcmp(MLX5_RXQ_PKT_PAD_EN, key) == 0) {
 		config->hw_padding = !!tmp;
 	} else if (strcmp(MLX5_RX_MPRQ_EN, key) == 0) {
@@ -1753,7 +1748,6 @@ mlx5_args(struct mlx5_dev_config *config, struct rte_devargs *devargs)
 {
 	const char **params = (const char *[]){
 		MLX5_RXQ_CQE_COMP_EN,
-		MLX5_RXQ_CQE_PAD_EN,
 		MLX5_RXQ_PKT_PAD_EN,
 		MLX5_RX_MPRQ_EN,
 		MLX5_RX_MPRQ_LOG_STRIDE_NUM,

drivers/net/mlx5/mlx5.h

@@ -207,7 +207,6 @@ struct mlx5_dev_config {
 	unsigned int mpls_en:1; /* MPLS over GRE/UDP is enabled. */
 	unsigned int cqe_comp:1; /* CQE compression is enabled. */
 	unsigned int cqe_comp_fmt:3; /* CQE compression format. */
-	unsigned int cqe_pad:1; /* CQE padding is enabled. */
 	unsigned int tso:1; /* Whether TSO is supported. */
 	unsigned int rx_vec_en:1; /* Rx vector is enabled. */
 	unsigned int mr_ext_memseg_en:1;