linux-kernel - [PATCH] igc: enable HW VLAN insertion/stripping by default

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Message-ID: <20250307110339.13788-1-rsalvaterra@gmail.com>
Date: Fri,  7 Mar 2025 11:02:39 +0000
From: Rui Salvaterra <rsalvaterra@...il.com>
To: muhammad.husaini.zulkifli@...el.com,
	anthony.l.nguyen@...el.com,
	przemyslaw.kitszel@...el.com
Cc: edumazet@...gle.com,
	kuba@...nel.org,
	netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Rui Salvaterra <rsalvaterra@...il.com>
Subject: [PATCH] igc: enable HW VLAN insertion/stripping by default

This is enabled by default in other Intel drivers I've checked (e1000, e1000e,
iavf, igb and ice). Fixes an out-of-the-box performance issue when running
OpenWrt on typical mini-PCs with igc-supported Ethernet controllers and 802.1Q
VLAN configurations, as ethtool isn't part of the default packages and sane
defaults are expected.

In my specific case, with an Intel N100-based machine with four I226-V Ethernet
controllers, my upload performance increased from under 30 Mb/s to the expected
~1 Gb/s.

Signed-off-by: Rui Salvaterra <rsalvaterra@...il.com>
---

This patch cost me two afternoons of network debugging, last weekend. Is there
any plausible reason why VLAN acceleration wasn't enabled by default for this
driver, specifically?

 drivers/net/ethernet/intel/igc/igc_main.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
index 84307bb7313e..6fef763239bc 100644
--- a/drivers/net/ethernet/intel/igc/igc_main.c
+++ b/drivers/net/ethernet/intel/igc/igc_main.c
@@ -7049,6 +7049,9 @@ static int igc_probe(struct pci_dev *pdev,
 	netdev->xdp_features = NETDEV_XDP_ACT_BASIC | NETDEV_XDP_ACT_REDIRECT |
 			       NETDEV_XDP_ACT_XSK_ZEROCOPY;

+	/* enable hardware VLAN insertion/stripping by default */
+	netdev->features |= NETIF_F_HW_VLAN_CTAG_TX | NETIF_F_HW_VLAN_CTAG_RX;
+
 	/* MTU range: 68 - 9216 */
 	netdev->min_mtu = ETH_MIN_MTU;
 	netdev->max_mtu = MAX_STD_JUMBO_FRAME_SIZE;
-- 
2.48.1