patch 'net/txgbe: fix inaccuracy in Tx rate limiting' has been queued to stable release 25.11.3

[Kevin Traynor]

Hi,

FYI, your patch has been queued to stable release 25.11.3

Note it hasn't been pushed to http://dpdk.org/browse/dpdk-stable yet.
It will be pushed if I get no objections before 08/04/26. 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/6b65875e2a84f777714c6d851b19c1e64bc93f15

Thanks.

Kevin

---
>From 6b65875e2a84f777714c6d851b19c1e64bc93f15 Mon Sep 17 00:00:00 2001
From: Zaiyu Wang <zaiyuwang at trustnetic.com>
Date: Wed, 24 Jun 2026 19:52:37 +0800
Subject: [PATCH] net/txgbe: fix inaccuracy in Tx rate limiting

[ upstream commit 4667f5aa613a9399944814333efc5b895954112d ]

Amber-lite NIC's TX rate limiting has large deviations for small
packets. To address this, the following changes are made:

1. Set TDM_RL_ADJ (0x1820c) to 21B (includes 7B Ethernet preamble,
   1B SFD, 1B EFD, and 12B IPG).
2) Remove the rate offset in the driver (e.g., 105 / 100, a rough
   compensation value from Linux kernel driver tests).

After these changes, accuracy deviation for 64B packets is within
~5%, while large packets show lower deviation.

Fixes: a309ab43acf3 ("net/txgbe: support Tx queue rate limiting for Amber-Lite")

Signed-off-by: Zaiyu Wang <zaiyuwang at trustnetic.com>
---
 drivers/net/txgbe/base/txgbe_regs.h | 3 +++
 drivers/net/txgbe/txgbe_ethdev.c    | 2 +-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/net/txgbe/base/txgbe_regs.h b/drivers/net/txgbe/base/txgbe_regs.h
index 95c585a025..3d1bc88430 100644
--- a/drivers/net/txgbe/base/txgbe_regs.h
+++ b/drivers/net/txgbe/base/txgbe_regs.h
@@ -1671,4 +1671,7 @@ enum txgbe_5tuple_protocol {
 #define   TXGBE_TDM_FACTOR_FRA_SHIFT    2
 
+#define TXGBE_TDM_RL_ADJ                0x1820C
+ /* Ethernet framing overhead: 7B Ethernet preamble + 1B SFD + 1B EFD + 12B IPG */
+#define   TXGBE_FRAME_OVERHEAD          21
 #define TXGBE_TDM_RL_VM_IDX             0x018218
 #define TXGBE_TDM_RL_VM_CFG             0x01821C
diff --git a/drivers/net/txgbe/txgbe_ethdev.c b/drivers/net/txgbe/txgbe_ethdev.c
index 779874aac9..099341b5ab 100644
--- a/drivers/net/txgbe/txgbe_ethdev.c
+++ b/drivers/net/txgbe/txgbe_ethdev.c
@@ -4315,5 +4315,4 @@ txgbe_set_queue_rate_limit(struct rte_eth_dev *dev,
 
 			link_speed = dev->data->dev_link.link_speed;
-			tx_rate  = tx_rate * 105 / 100;
 			/* Calculate the rate factor values to set */
 			factor_int = link_speed / tx_rate;
@@ -4325,4 +4324,5 @@ txgbe_set_queue_rate_limit(struct rte_eth_dev *dev,
 			}
 
+			wr32(hw, TXGBE_TDM_RL_ADJ, TXGBE_FRAME_OVERHEAD);
 			wr32(hw, TXGBE_TDM_RL_QUEUE_IDX, queue_idx);
 			wr32m(hw, TXGBE_TDM_RL_QUEUE_CFG,
-- 
2.55.0

---
  Diff of the applied patch vs upstream commit (please double-check if non-empty:
---
--- -	2026-07-30 10:16:01.659404952 +0100
+++ 0005-net-txgbe-fix-inaccuracy-in-Tx-rate-limiting.patch	2026-07-30 10:16:01.424990816 +0100
@@ -1 +1 @@
-From 4667f5aa613a9399944814333efc5b895954112d Mon Sep 17 00:00:00 2001
+From 6b65875e2a84f777714c6d851b19c1e64bc93f15 Mon Sep 17 00:00:00 2001
@@ -5,0 +6,2 @@
+[ upstream commit 4667f5aa613a9399944814333efc5b895954112d ]
+
@@ -18 +19,0 @@
-Cc: stable at dpdk.org
@@ -39 +40 @@
-index 77870f3aee..c97a7f1a4e 100644
+index 779874aac9..099341b5ab 100644