From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <netdev-owner@kernel.org>
X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on
	aws-us-west-2-korg-lkml-1.web.codeaurora.org
Received: from vger.kernel.org (vger.kernel.org [23.128.96.18])
	by smtp.lore.kernel.org (Postfix) with ESMTP id C3D22C433EF
	for <netdev@archiver.kernel.org>; Tue, 24 May 2022 16:00:22 +0000 (UTC)
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S239398AbiEXQAU (ORCPT <rfc822;netdev@archiver.kernel.org>);
        Tue, 24 May 2022 12:00:20 -0400
Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46356 "EHLO
        lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S239309AbiEXQAP (ORCPT
        <rfc822;netdev@vger.kernel.org>); Tue, 24 May 2022 12:00:15 -0400
Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217])
        by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 63DF39AE7B;
        Tue, 24 May 2022 09:00:01 -0700 (PDT)
Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140])
        (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))
        (No client certificate requested)
        by dfw.source.kernel.org (Postfix) with ESMTPS id 84B1A61769;
        Tue, 24 May 2022 16:00:00 +0000 (UTC)
Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5A025C34115;
        Tue, 24 May 2022 15:59:58 +0000 (UTC)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org;
        s=k20201202; t=1653407999;
        bh=B0fbzs5NVpRoXeOmEKHVbepGaopA9N/slql/ABvPCnI=;
        h=From:To:Cc:Subject:Date:In-Reply-To:References:From;
        b=oXtEgWFMuz1RF7Wup01zcpvlwR8nXyXwIMKi+H3xb+geIOd/ajnxHRo1H7ErJtzLq
         9CKYC1Qf9fK5qvWUGoKNNCP1urrvlbAWE+u36UkUT1rFZ7K0RrQbfRLW+QWlouoPXa
         p8b+fS39jwJbLrXtzWlBbXfuQMaNPvhqUUxfMEJlQqsP0qeudMAKIOcf+U46dAfDJX
         wj/khUHqtFdQFRJFsi6q5zZDVIj4vPb01yEyPonA86a4d/MyQdohz8KyN4uzQV2Tta
         SeE1Ftyd7S5wHTZYBTyXrlAblwG0yybaALGi1AiPnb7ko0rSyuG3qIkwunQqvRhT2T
         eJAZlyF6Ze7MA==
From:   Sasha Levin <sashal@kernel.org>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc:     Joel Stanley <joel@jms.id.au>, David Wilder <wilder@us.ibm.com>,
        Dylan Hung <dylan_hung@aspeedtech.com>,
        "David S . Miller" <davem@davemloft.net>,
        Sasha Levin <sashal@kernel.org>, edumazet@google.com,
        kuba@kernel.org, pabeni@redhat.com, guoheyi@linux.alibaba.com,
        arnd@arndb.de, chenhao288@hisilicon.com, netdev@vger.kernel.org
Subject: [PATCH AUTOSEL 5.17 10/12] net: ftgmac100: Disable hardware checksum on AST2600
Date:   Tue, 24 May 2022 11:59:24 -0400
Message-Id: <20220524155929.826793-10-sashal@kernel.org>
X-Mailer: git-send-email 2.35.1
In-Reply-To: <20220524155929.826793-1-sashal@kernel.org>
References: <20220524155929.826793-1-sashal@kernel.org>
MIME-Version: 1.0
X-stable: review
X-Patchwork-Hint: Ignore
Content-Transfer-Encoding: 8bit
Precedence: bulk
List-ID: <netdev.vger.kernel.org>
X-Mailing-List: netdev@vger.kernel.org

From: Joel Stanley <joel@jms.id.au>

[ Upstream commit 6fd45e79e8b93b8d22fb8fe22c32fbad7e9190bd ]

The AST2600 when using the i210 NIC over NC-SI has been observed to
produce incorrect checksum results with specific MTU values. This was
first observed when sending data across a long distance set of networks.

On a local network, the following test was performed using a 1MB file of
random data.

On the receiver run this script:

 #!/bin/bash
 while [ 1 ]; do
        # Zero the stats
        nstat -r  > /dev/null
        nc -l 9899 > test-file
        # Check for checksum errors
        TcpInCsumErrors=$(nstat | grep TcpInCsumErrors)
        if [ -z "$TcpInCsumErrors" ]; then
                echo No TcpInCsumErrors
        else
                echo TcpInCsumErrors = $TcpInCsumErrors
        fi
 done

On an AST2600 system:

 # nc <IP of  receiver host> 9899 < test-file

The test was repeated with various MTU values:

 # ip link set mtu 1410 dev eth0

The observed results:

 1500 - good
 1434 - bad
 1400 - good
 1410 - bad
 1420 - good

The test was repeated after disabling tx checksumming:

 # ethtool -K eth0 tx-checksumming off

And all MTU values tested resulted in transfers without error.

An issue with the driver cannot be ruled out, however there has been no
bug discovered so far.

David has done the work to take the original bug report of slow data
transfer between long distance connections and triaged it down to this
test case.

The vendor suspects this this is a hardware issue when using NC-SI. The
fixes line refers to the patch that introduced AST2600 support.

Reported-by: David Wilder <wilder@us.ibm.com>
Reviewed-by: Dylan Hung <dylan_hung@aspeedtech.com>
Signed-off-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/ethernet/faraday/ftgmac100.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/ethernet/faraday/ftgmac100.c b/drivers/net/ethernet/faraday/ftgmac100.c
index caf48023f8ea..5231818943c6 100644
--- a/drivers/net/ethernet/faraday/ftgmac100.c
+++ b/drivers/net/ethernet/faraday/ftgmac100.c
@@ -1928,6 +1928,11 @@ static int ftgmac100_probe(struct platform_device *pdev)
 	/* AST2400  doesn't have working HW checksum generation */
 	if (np && (of_device_is_compatible(np, "aspeed,ast2400-mac")))
 		netdev->hw_features &= ~NETIF_F_HW_CSUM;
+
+	/* AST2600 tx checksum with NCSI is broken */
+	if (priv->use_ncsi && of_device_is_compatible(np, "aspeed,ast2600-mac"))
+		netdev->hw_features &= ~NETIF_F_HW_CSUM;
+
 	if (np && of_get_property(np, "no-hw-checksum", NULL))
 		netdev->hw_features &= ~(NETIF_F_HW_CSUM | NETIF_F_RXCSUM);
 	netdev->features |= netdev->hw_features;
-- 
2.35.1