From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 938EF35292A; Tue, 16 Jun 2026 18:19:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781633981; cv=none; b=WPsS6SNtfr3ec8c8lcbaZ/tAZYXq53y/rXj43tGOVw0RmbZoblLIHhXFm5a7XEm2dfkPVfiof6fBnodRrBe+JGICHFp86ZlKYqcCsoBUhXWLcGT4LEIPZ6PXXzqD7VpOLRs8ab17AA2z3keR1WTV/5u1YVIiI70Tg04NEbdCFUc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781633981; c=relaxed/simple; bh=sgXp11dCD13tuaEqMn+YKggoXzPDi0Zvgi9Wur7GdHE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=U3ztwBgLBdz1I7/ws6ce0W8E2ktF8ce0zfGRZLW9hRYw39Yqwl3QZ4yLHJiGP5h8Wf/+JGYhiUUy6IIpnDnQbk7NgZNOuzFiMHO5B//H51YhJ0ywbVUXOyfj18dpudhFzX3WK5vRi/tj1KJ58RSrNSuBeGPVD0LHXswjlqHcN80= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=aUUz1wyg; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="aUUz1wyg" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7B7391F000E9; Tue, 16 Jun 2026 18:19:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1781633980; bh=A+JLg9WZtin89emdSl1uROQGkhiBBWg5VZzgpuEiYHA=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=aUUz1wygggPIgXuYpd19EgVcNMpr/vr4YfkUytXxPIrbg+KQt+2O17BRC49lnuYp4 SkyZIQMM7Bgid5675mVVefCaatIFo3QF2UJ6gQXJI/ftHD3IS1RTc4PvLZbXoYb5m4 Tu2uznTHA6hEzX2QzDZYRaDoe0B8w0tJVshRkucE= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, David Thompson , Thangaraj Samynathan , Nicolai Buchwitz , Jakub Kicinski , Sasha Levin Subject: [PATCH 5.15 161/411] net: lan743x: permit VLAN-tagged packets up to configured MTU Date: Tue, 16 Jun 2026 20:26:39 +0530 Message-ID: <20260616145109.063225340@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260616145100.376842714@linuxfoundation.org> References: <20260616145100.376842714@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: David Thompson [ Upstream commit 8173d22b211f615015f7b35f48ab11a6dd78dc99 ] VLAN-tagged interfaces on lan743x devices were previously unreachable via SSH and failed to respond to large ping packets (e.g. "ping -s 1469" given MTU=1500). In these scenarios, "ethtool -S" reports non-zero "RX Oversize Frame Errors". According to Microchip AN2948, the MAC_RX FSE (VLAN field size enforcement) bit determines whether frames with VLAN tags exceeding the base MTU plus tag length are discarded. The driver must set the MAC_RX.FSE bit before setting MAC_RX.RXEN to allow VLAN-tagged frames up to the interface MTU, preventing them from being treated as oversized. As a result, both the base and VLAN-tagged interfaces can use the same MTU without receive errors. Fixes: 23f0703c125b ("lan743x: Add main source files for new lan743x driver") Signed-off-by: David Thompson Reviewed-by: Thangaraj Samynathan Reviewed-by: Nicolai Buchwitz Tested-by: Nicolai Buchwitz # lan7430 on arm64 (RevPi Link: https://patch.msgid.link/20260529210300.433135-1-davthompson@nvidia.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- drivers/net/ethernet/microchip/lan743x_main.c | 32 +++++++++++++++++++ drivers/net/ethernet/microchip/lan743x_main.h | 1 + 2 files changed, 33 insertions(+) diff --git a/drivers/net/ethernet/microchip/lan743x_main.c b/drivers/net/ethernet/microchip/lan743x_main.c index 49d40685136d46..8db83741aaa570 100644 --- a/drivers/net/ethernet/microchip/lan743x_main.c +++ b/drivers/net/ethernet/microchip/lan743x_main.c @@ -792,6 +792,36 @@ static void lan743x_mac_set_address(struct lan743x_adapter *adapter, "MAC address set to %pM\n", addr); } +static void lan743x_mac_rx_enable_fse(struct lan743x_adapter *adapter) +{ + u32 mac_rx; + bool rxen; + + mac_rx = lan743x_csr_read(adapter, MAC_RX); + if (mac_rx & MAC_RX_FSE_) + return; + + rxen = mac_rx & MAC_RX_RXEN_; + if (rxen) { + mac_rx &= ~MAC_RX_RXEN_; + lan743x_csr_write(adapter, MAC_RX, mac_rx); + lan743x_csr_wait_for_bit(adapter, MAC_RX, MAC_RX_RXD_, + 1, 1000, 20000, 100); + } + + /* Per AN2948, hardware prevents modification of the FSE bit while the + * MAC receiver is enabled (RXEN bit set). Use separate register write + * to assert the FSE bit before enabling the RXEN bit in MAC_RX + */ + mac_rx |= MAC_RX_FSE_; + lan743x_csr_write(adapter, MAC_RX, mac_rx); + + if (rxen) { + mac_rx |= MAC_RX_RXEN_; + lan743x_csr_write(adapter, MAC_RX, mac_rx); + } +} + static int lan743x_mac_init(struct lan743x_adapter *adapter) { bool mac_address_valid = true; @@ -831,6 +861,8 @@ static int lan743x_mac_init(struct lan743x_adapter *adapter) lan743x_mac_set_address(adapter, adapter->mac_address); eth_hw_addr_set(netdev, adapter->mac_address); + lan743x_mac_rx_enable_fse(adapter); + return 0; } diff --git a/drivers/net/ethernet/microchip/lan743x_main.h b/drivers/net/ethernet/microchip/lan743x_main.h index a1226ab0fb4217..40351d38299aac 100644 --- a/drivers/net/ethernet/microchip/lan743x_main.h +++ b/drivers/net/ethernet/microchip/lan743x_main.h @@ -118,6 +118,7 @@ #define MAC_RX (0x104) #define MAC_RX_MAX_SIZE_SHIFT_ (16) #define MAC_RX_MAX_SIZE_MASK_ (0x3FFF0000) +#define MAC_RX_FSE_ BIT(2) #define MAC_RX_RXD_ BIT(1) #define MAC_RX_RXEN_ BIT(0) -- 2.53.0