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Sun, 18 Jan 2026 23:37:08 -0800 (PST) Received: from nbai25050028.lan ([2409:4090:807d:4601:b49b:a111:92a3:e6d0]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-c5edf32d1f1sm8170540a12.22.2026.01.18.23.37.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 18 Jan 2026 23:37:07 -0800 (PST) From: Sayantan Nandy To: lorenzo@kernel.org Cc: linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, netdev@vger.kernel.org, sayantan.nandy@airoha.com, bread.hsu@airoha.com, kuldeep.malik@airoha.com, aniket.negi@airoha.com, brown.huang@airoha.com, Sayantan Nandy Subject: [PATCH net-next v3] net: airoha_eth: increase max MTU to 9220 for DSA jumbo frames Date: Mon, 19 Jan 2026 13:06:58 +0530 Message-ID: <20260119073658.6216-1-sayantann11@gmail.com> X-Mailer: git-send-email 2.43.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260118_233709_710594_46C16EDA X-CRM114-Status: GOOD ( 11.73 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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 --- v3: - Document that hardware supports larger MTU (~16K), but limit to 9220 for now - Target net-next (netdev/main) as this is a feature enhancement - No functional changes v2: - Clarified commit message regarding DSA tag overhead drivers/net/ethernet/airoha/airoha_eth.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/net/ethernet/airoha/airoha_eth.h b/drivers/net/ethernet/airoha/airoha_eth.h index fbbc58133364..20e602d61e61 100644 --- 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 -- 2.43.0