[dpdk-dev] [PATCH] net/nfp: fix data offset initialization in TX descriptors

[Alejandro Lucero <alejandro.lucero@netronome.com>]

The mbuf struct allows to prepend metadata and the NFP TX
descriptors needs to give the data offset to the NIC.

There is no application using this metadata but it is possible
the PMD itself using it in the future for supporting hardware
offloads like OVS offload.

Also, this patch fixes a potential issue with the offset bits inside
the TX descriptor not being used nor initialized, but the firmware
checking it and doing the wrong thing if the offset bits contain
garbage.

Fixes: b812daadad0d ("nfp: add Rx and Tx")

Signed-off-by: Alejandro Lucero <alejandro.lucero@netronome.com>
---
 drivers/net/nfp/nfp_net.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/net/nfp/nfp_net.c b/drivers/net/nfp/nfp_net.c
index faad1ee..14f7fc0 100644
--- a/drivers/net/nfp/nfp_net.c
+++ b/drivers/net/nfp/nfp_net.c
@@ -2245,6 +2245,14 @@ uint32_t nfp_net_txq_full(struct nfp_net_txq *txq)
 			txds->data_len = txd.data_len;
 			txds->dma_addr_hi = (dma_addr >> 32) & 0xff;
 			txds->dma_addr_lo = (dma_addr & 0xffffffff);
+
+			/*
+			 * Prepend metadata?
+			 * NFP has just support for a 7 bits offset
+			 */
+			txds->offset_eop = (uint8_t)pkt->data_off &
+					   PCIE_DESC_TX_OFFSET_MASK;
+
 			ASSERT(free_descs > 0);
 			free_descs--;
 
-- 
1.9.1