[dpdk-dev] [PATCH v7 2/2] net/ark: remove RTE_LIBRTE_ARK_PAD_TX configuration macro

[Ed Czeck]

Replace behavior with RTE_LIBRTE_ARK_MIN_TX_PKTLEN
with a default value of 0.
Update documentation as needed.

Signed-off-by: Ed Czeck <ed.czeck at atomicrules.com>
---
v7:
  -- add ARK_MIN_TX_PKTLEN to conditional expression
    to avoid compile warning with icc.
  -- restore CONFIG_RTE_LIBRTE_ARK_PMD doc as requested.
---
 doc/guides/nics/ark.rst         | 13 ++++++++--
 drivers/net/ark/ark_ethdev_tx.c | 43 ++++++++++++++++++---------------
 drivers/net/ark/ark_logs.h      |  8 ------
 3 files changed, 35 insertions(+), 29 deletions(-)

diff --git a/doc/guides/nics/ark.rst b/doc/guides/nics/ark.rst
index c3ffcbbc2..358e7f624 100644
--- a/doc/guides/nics/ark.rst
+++ b/doc/guides/nics/ark.rst
@@ -129,8 +129,10 @@ Configuration Information
    * **CONFIG_RTE_LIBRTE_ARK_PMD** (default y): Enables or disables inclusion
      of the ARK PMD driver in the DPDK compilation.
 
-   * **CONFIG_RTE_LIBRTE_ARK_PAD_TX** (default y):  When enabled TX
-     packets are padded to 60 bytes to support downstream MACS.
+   * **RTE_LIBRTE_ARK_MIN_TX_PKTLEN** (default 0): Sets the minimum
+     packet length for tx packets to the FPGA.  Packets less than this
+     length are padded to meet the requirement. This allows padding to
+     be offloaded or remain in host software.
 
 
 Building DPDK
@@ -144,6 +146,13 @@ By default the ARK PMD library will be built into the DPDK library.
 For configuring and using UIO and VFIO frameworks, please also refer :ref:`the
 documentation that comes with DPDK suite <linux_gsg>`.
 
+To build with a non-zero minimum tx packet length, set the above macro in your
+CFLAGS environment prior to the meson build step. I.e.,
+
+    export CFLAGS="-DRTE_LIBRTE_ARK_MIN_TX_PKTLEN=60"
+    meson build
+
+
 Supported ARK RTL PCIe Instances
 --------------------------------
 
diff --git a/drivers/net/ark/ark_ethdev_tx.c b/drivers/net/ark/ark_ethdev_tx.c
index 72624deb3..a0e35af88 100644
--- a/drivers/net/ark/ark_ethdev_tx.c
+++ b/drivers/net/ark/ark_ethdev_tx.c
@@ -14,6 +14,11 @@
 #define ARK_TX_META_OFFSET (RTE_PKTMBUF_HEADROOM - ARK_TX_META_SIZE)
 #define ARK_TX_MAX_NOCHAIN (RTE_MBUF_DEFAULT_DATAROOM)
 
+#ifndef RTE_LIBRTE_ARK_MIN_TX_PKTLEN
+#define ARK_MIN_TX_PKTLEN 0
+#else
+#define ARK_MIN_TX_PKTLEN RTE_LIBRTE_ARK_MIN_TX_PKTLEN
+#endif
 
 /* ************************************************************************* */
 struct ark_tx_queue {
@@ -91,6 +96,7 @@ eth_ark_xmit_pkts(void *vtxq, struct rte_mbuf **tx_pkts, uint16_t nb_pkts)
 	uint32_t prod_index_limit;
 	int stat;
 	uint16_t nb;
+	const uint32_t min_pkt_len = ARK_MIN_TX_PKTLEN;
 
 	queue = (struct ark_tx_queue *)vtxq;
 
@@ -104,27 +110,26 @@ eth_ark_xmit_pkts(void *vtxq, struct rte_mbuf **tx_pkts, uint16_t nb_pkts)
 	     ++nb) {
 		mbuf = tx_pkts[nb];
 
-		if (ARK_TX_PAD_TO_60) {
-			if (unlikely(rte_pktmbuf_pkt_len(mbuf) < 60)) {
-				/* this packet even if it is small can be split,
-				 * be sure to add to the end mbuf
+		if (min_pkt_len &&
+		    unlikely(rte_pktmbuf_pkt_len(mbuf) < min_pkt_len)) {
+			/* this packet even if it is small can be split,
+			 * be sure to add to the end mbuf
+			 */
+			uint16_t to_add = min_pkt_len -
+				rte_pktmbuf_pkt_len(mbuf);
+			char *appended =
+				rte_pktmbuf_append(mbuf, to_add);
+
+			if (appended == 0) {
+				/* This packet is in error,
+				 * we cannot send it so just
+				 * count it and delete it.
 				 */
-				uint16_t to_add =
-					60 - rte_pktmbuf_pkt_len(mbuf);
-				char *appended =
-					rte_pktmbuf_append(mbuf, to_add);
-
-				if (appended == 0) {
-					/* This packet is in error,
-					 * we cannot send it so just
-					 * count it and delete it.
-					 */
-					queue->tx_errors += 1;
-					rte_pktmbuf_free(mbuf);
-					continue;
-				}
-				memset(appended, 0, to_add);
+				queue->tx_errors += 1;
+				rte_pktmbuf_free(mbuf);
+				continue;
 			}
+			memset(appended, 0, to_add);
 		}
 
 		if (unlikely(mbuf->nb_segs != 1)) {
diff --git a/drivers/net/ark/ark_logs.h b/drivers/net/ark/ark_logs.h
index c3d7e7d39..ca46d86c9 100644
--- a/drivers/net/ark/ark_logs.h
+++ b/drivers/net/ark/ark_logs.h
@@ -8,14 +8,6 @@
 #include <inttypes.h>
 #include <rte_log.h>
 
-
-/* Configuration option to pad TX packets to 60 bytes */
-#ifdef RTE_LIBRTE_ARK_PAD_TX
-#define ARK_TX_PAD_TO_60   1
-#else
-#define ARK_TX_PAD_TO_60   0
-#endif
-
 /* system camel case definition changed to upper case */
 #define PRIU32 PRIu32
 #define PRIU64 PRIu64
-- 
2.17.1