From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from pandora.armlinux.org.uk (pandora.armlinux.org.uk [78.32.30.218]) (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 288B426B75C; Tue, 18 Nov 2025 08:23:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=78.32.30.218 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763454245; cv=none; b=dVNJJ/otx854sTVdyj/PGSzIjN+A6opQWxw7dGNMHhO6FMNnjEZuG16NAWuFHmiSkpcfOPLu5nuGsxzVG8N/ti7TfLVv0FJk3R7BQc6obnyqwVXN8xCSXCaXZAb9AAwKhl5FefCel7oJA1fpbzubfDFAB1MZZZIJdWlE/Z+NP0M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763454245; c=relaxed/simple; bh=GWBWi6n/09s4UFkCZrc4hn3vheoXtmdjxbEXTYUz66I=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=tzhdQj4sB6UDMEBmSQvfsiLDBvKsg/QWy2BBobkX+ytKeOYoBB90r8KQ+P+pzr3VpYHGnwlS+5LsbMhOqsvjvWY5tlYdXO1DT3yRByiRvoT8rMtmx3IdBtZHXTUiJU4k3KKC9uv3yId42p000xSp7A6TwK40ZJSXTq0kbnhD1BA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=armlinux.org.uk; spf=none smtp.mailfrom=armlinux.org.uk; dkim=pass (2048-bit key) header.d=armlinux.org.uk header.i=@armlinux.org.uk header.b=XzsDB1G9; arc=none smtp.client-ip=78.32.30.218 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=armlinux.org.uk Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=armlinux.org.uk Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=armlinux.org.uk header.i=@armlinux.org.uk header.b="XzsDB1G9" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=armlinux.org.uk; s=pandora-2019; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=8SLu1N6OkiZOCKYpKcgBHYGaJlgn3HankT7fWKAAW+g=; b=XzsDB1G9tH6y6Am4sthjbvOngF F84JB9kQMPJ/3gUMA8ErN74tm83ExxYGIC5MQhG0I9pMt9u4VIfAO+tO5vInKyPiu4CbNeIUVg1i/ NsWjhcBW2hhaz7Cf5fbeufgQFsaM8OlplZ1hjTnTRlwEaKUVhw3shh6OOslzqx7XUcmW/wxMKmswL BczBrSBZRRs2j3ghXL+RHYXJ/V/sNbaCD59TVansTjdcoGrPrY/SFK9ZdJqmtbSepTP4kshJjI4Ij MX17udDSBe9XcHZpmj3Vvd5KQ9viTYzHryqBBOxk5rLdZ1J2NeurXaHwsFihy5aO8byOTL03V/0uU WiF4jyTw==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:57590) by pandora.armlinux.org.uk with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.98.2) (envelope-from ) id 1vLH0A-000000002uO-1cZE; Tue, 18 Nov 2025 08:23:50 +0000 Received: from linux by shell.armlinux.org.uk with local (Exim 4.98.2) (envelope-from ) id 1vLH05-000000002Jb-2EVx; Tue, 18 Nov 2025 08:23:45 +0000 Date: Tue, 18 Nov 2025 08:23:45 +0000 From: "Russell King (Oracle)" To: Wei Fang Cc: andrew@lunn.ch, hkallweit1@gmail.com, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, eric@nelint.com, maxime.chevallier@bootlin.com, imx@lists.linux.dev, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 net] net: phylink: add missing supported link modes for the fixed-link Message-ID: References: <20251117102943.1862680-1-wei.fang@nxp.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251117102943.1862680-1-wei.fang@nxp.com> Sender: Russell King (Oracle) On Mon, Nov 17, 2025 at 06:29:43PM +0800, Wei Fang wrote: > Pause, Asym_Pause and Autoneg bits are not set when pl->supported is > initialized, so these link modes will not work for the fixed-link. This > leads to a TCP performance degradation issue observed on the i.MX943 > platform. > > The switch CPU port of i.MX943 is connected to an ENETC MAC, this link > is a fixed link and the link speed is 2.5Gbps. And one of the switch > user ports is the RGMII interface, and its link speed is 1Gbps. If the > flow-control of the fixed link is not enabled, we can easily observe > the iperf performance of TCP packets is very low. Because the inbound > rate on the CPU port is greater than the outbound rate on the user port, > the switch is prone to congestion, leading to the loss of some TCP > packets and requiring multiple retransmissions. > > Solving this problem should be as simple as setting the Asym_Pause and > Pause bits. The reason why the Autoneg bit needs to be set, Russell > has gave a very good explanation in the thread [1], see below. > > "As the advertising and lp_advertising bitmasks have to be non-empty, > and the swphy reports aneg capable, aneg complete, and AN enabled, then > for consistency with that state, Autoneg should be set. This is how it > was prior to the blamed commit." > > [1] https://lore.kernel.org/all/aRjqLN8eQDIQfBjS@shell.armlinux.org.uk/ > > Fixes: de7d3f87be3c ("net: phylink: Use phy_caps_lookup for fixed-link configuration") > Signed-off-by: Wei Fang > Reviewed-by: Maxime Chevallier NAK. I give up. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!