From 6406fc709ace081575de2a8a7eee12e63d4c96c6 Mon Sep 17 00:00:00 2001
From: Sayantan Nandy <sayantann11@gmail.com>
Date: Mon, 19 Jan 2026 13:06:58 +0530
Subject: [PATCH] net: airoha_eth: increase max MTU to 9220 for DSA jumbo
 frames

The industry standard jumbo frame MTU is 9216 bytes. When using the DSA
subsystem, a 4-byte tag is added to each Ethernet frame.

Increase AIROHA_MAX_MTU to 9220 bytes (9216 + 4) so that users can set a
standard 9216-byte MTU on DSA ports.

The underlying hardware supports significantly larger frame sizes
(approximately 16K). However, the maximum MTU is limited to 9220 bytes
for now, as this is sufficient to support standard jumbo frames and does
not incur additional memory allocation overhead.

Signed-off-by: Sayantan Nandy <sayantann11@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Acked-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://patch.msgid.link/20260119073658.6216-1-sayantann11@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
 drivers/net/ethernet/airoha/airoha_eth.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/net/ethernet/airoha/airoha_eth.h
+++ b/drivers/net/ethernet/airoha/airoha_eth.h
@@ -21,7 +21,7 @@
 #define AIROHA_MAX_NUM_IRQ_BANKS	4
 #define AIROHA_MAX_DSA_PORTS		7
 #define AIROHA_MAX_NUM_RSTS		3
-#define AIROHA_MAX_MTU			9216
+#define AIROHA_MAX_MTU			9220
 #define AIROHA_MAX_PACKET_SIZE		2048
 #define AIROHA_NUM_QOS_CHANNELS		4
 #define AIROHA_NUM_QOS_QUEUES		8
