patch 'net/e1000: fix allocation of context desc for launch time' has been queued to stable release 25.11.1

[Kevin Traynor]

Hi,

FYI, your patch has been queued to stable release 25.11.1

Note it hasn't been pushed to http://dpdk.org/browse/dpdk-stable yet.
It will be pushed if I get no objections before 03/02/26. So please
shout if anyone has objections.

Also note that after the patch there's a diff of the upstream commit vs the
patch applied to the branch. This will indicate if there was any rebasing
needed to apply to the stable branch. If there were code changes for rebasing
(ie: not only metadata diffs), please double check that the rebase was
correctly done.

Queued patches are on a temporary branch at:
https://github.com/kevintraynor/dpdk-stable

This queued commit can be viewed at:
https://github.com/kevintraynor/dpdk-stable/commit/4c0c66d9c2919f2c27ccf10be64e6f8843c424eb

Thanks.

Kevin

---
>From 4c0c66d9c2919f2c27ccf10be64e6f8843c424eb Mon Sep 17 00:00:00 2001
From: Song Yoong Siang <yoong.siang.song at intel.com>
Date: Thu, 4 Dec 2025 09:30:08 +0800
Subject: [PATCH] net/e1000: fix allocation of context desc for launch time

[ upstream commit fc9ff0bcabe73a70d5ae8a235601734d89abdd69 ]

When the timestamp dynamic flag is set in the mbuf offload flags, force
allocation of a new context descriptor. The launch time feature requires
a dedicated context descriptor to specify the desired launch time for
packet.

Testing was performed on two Intel ADL-S platforms with i226 NICs
connected back-to-back. A DPDK sample application is created to send two
bursts of packets with 100,000 nanosecond burst interval. Each burst is
having 5 UDP packets and only the first packet in the burst using launch
time feature. Meanwhile, the tcpdump command below is used on the link
partner to capture the delta of Rx hardware timestamp of the 10 packets:

tcpdump -ttt -ni enp1s0 --time-stamp-precision=nano -j adapter_unsynced

Without this patch, packets of second burst are transmitted immediately
as the driver din't create context descriptor for the launch time, as
shown in tcpdump log below:

  00:00:00.000000000 IP 192.168.1.100.2 > 224.1.1.1.5: UDP, length 982
  00:00:00.000008384 IP 192.168.1.100.2 > 224.1.1.1.5: UDP, length 982
  00:00:00.000008381 IP 192.168.1.100.2 > 224.1.1.1.5: UDP, length 982
  00:00:00.000008384 IP 192.168.1.100.2 > 224.1.1.1.5: UDP, length 982
  00:00:00.000008384 IP 192.168.1.100.2 > 224.1.1.1.5: UDP, length 982
  00:00:00.000008384 IP 192.168.1.100.2 > 224.1.1.1.5: UDP, length 982
  00:00:00.000008387 IP 192.168.1.100.2 > 224.1.1.1.5: UDP, length 982
  00:00:00.000008384 IP 192.168.1.100.2 > 224.1.1.1.5: UDP, length 982
  00:00:00.000008381 IP 192.168.1.100.2 > 224.1.1.1.5: UDP, length 982
  00:00:00.000008387 IP 192.168.1.100.2 > 224.1.1.1.5: UDP, length 982

With this patch, packets of second burst are properly held until the
intended 100,000 nanosecond intervals, demonstrating correct launch time
behavior. As shown in tcpdump log below, the delta of first packet
between first and second bursts is 8387 + 8384 + 8384 + 8384 + 66461 =
100,000 nanosecond.

  00:00:00.000000000 IP 192.168.1.100.2 > 224.1.1.1.5: UDP, length 982
  00:00:00.000008387 IP 192.168.1.100.2 > 224.1.1.1.5: UDP, length 982
  00:00:00.000008384 IP 192.168.1.100.2 > 224.1.1.1.5: UDP, length 982
  00:00:00.000008384 IP 192.168.1.100.2 > 224.1.1.1.5: UDP, length 982
  00:00:00.000008384 IP 192.168.1.100.2 > 224.1.1.1.5: UDP, length 982
  00:00:00.000066461 IP 192.168.1.100.2 > 224.1.1.1.5: UDP, length 982
  00:00:00.000008387 IP 192.168.1.100.2 > 224.1.1.1.5: UDP, length 982
  00:00:00.000008384 IP 192.168.1.100.2 > 224.1.1.1.5: UDP, length 982
  00:00:00.000008384 IP 192.168.1.100.2 > 224.1.1.1.5: UDP, length 982
  00:00:00.000008384 IP 192.168.1.100.2 > 224.1.1.1.5: UDP, length 982

Fixes: 9630f7c71ecd ("net/igc: enable launch time offloading")

Signed-off-by: David Zage <david.zage at intel.com>
Signed-off-by: Song Yoong Siang <yoong.siang.song at intel.com>
Acked-by: Bruce Richardson <bruce.richardson at intel.com>
---
 drivers/net/intel/e1000/igc_txrx.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/net/intel/e1000/igc_txrx.c b/drivers/net/intel/e1000/igc_txrx.c
index f2a6c34094..35f36d266a 100644
--- a/drivers/net/intel/e1000/igc_txrx.c
+++ b/drivers/net/intel/e1000/igc_txrx.c
@@ -1417,4 +1417,8 @@ what_advctx_update(struct igc_tx_queue *txq, uint64_t flags,
 	uint32_t curr = txq->ctx_curr;
 
+	/* Launch time feature always need a new context descriptor */
+	if (flags & igc_tx_timestamp_dynflag)
+		return IGC_CTX_NUM;
+
 	/* If match with the current context */
 	if (likely(txq->ctx_cache[curr].flags == flags &&
@@ -1622,5 +1626,6 @@ igc_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts, uint16_t nb_pkts)
 
 		ol_flags = tx_pkt->ol_flags;
-		tx_ol_req = ol_flags & IGC_TX_OFFLOAD_MASK;
+		tx_ol_req = ol_flags & (IGC_TX_OFFLOAD_MASK |
+				igc_tx_timestamp_dynflag);
 
 		/* If a Context Descriptor need be built . */
-- 
2.53.0

---
  Diff of the applied patch vs upstream commit (please double-check if non-empty:
---
--- -	2026-02-26 10:16:49.196677721 +0000
+++ 0053-net-e1000-fix-allocation-of-context-desc-for-launch-.patch	2026-02-26 10:16:46.971459325 +0000
@@ -1 +1 @@
-From fc9ff0bcabe73a70d5ae8a235601734d89abdd69 Mon Sep 17 00:00:00 2001
+From 4c0c66d9c2919f2c27ccf10be64e6f8843c424eb Mon Sep 17 00:00:00 2001
@@ -5,0 +6,2 @@
+[ upstream commit fc9ff0bcabe73a70d5ae8a235601734d89abdd69 ]
+
@@ -53 +54,0 @@
-Cc: stable at dpdk.org