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 EDE5014C583; Fri, 2 Feb 2024 18:06:02 +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=1706897164; cv=none; b=hNeKMDcs8m0I5YvlWD3R/FZmIPcbVJ1U7intaFYXt8Q09RdgcDg5WnI0gviODlthEON8dHmOdTQ9R6toKnM06dduzT8tLo7+gsgu8LBevXgyvlon3Tb30faTHWbFXgCwjddm/UdmvQfIXn9fTIRH2FBa6YOpt+RWveKiqLW1rlU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706897164; c=relaxed/simple; bh=0+zBy9BxMtmgrUapuuE00XzrLUjsL9pi4V6VkVRtgQc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=PXaG4UKtNVueO/ezoYbf9TniHFspnIhvoQInFK0mlQBtUkzMveXJnqoNFe8L9tl88KUMDyJNYvTh89a6VwzbRbqbUud4QVA1+0b1z/6ZbZL1snuPHwLFag0/TWMA/pBd7R8W0LQQvU9WrCylT0NK6ABRyrDsRxbNUyEjy4X5Qmg= 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=ObLXNAjP; 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="ObLXNAjP" 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-Transfer-Encoding:Content-Type:MIME-Version:References:Message-ID: Subject:Cc:To:From:Date:Reply-To: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=h2ATmObSzV4eeYzY6CoQyZq/5jRI5DOKZsLmwWQtw3M=; b=ObLXNAjPuveYNFk2FxXGhxn30h 0eMSF4JCx6nTaY5ps/qixLTdCG9nttzdB4vmXGfi1dhc0Lm+mlwVLIWjISDlCqhO22LkaLGM8bRh/ ZgYJoAqIqdCU+b140Zls+zIInP9AYeteqn0e438kukRymDf+y9BygXSO56Ns6K0YplJGZTdhFXtIC BS/gtnnwuIyYzoiBscjrIpTLWBj2/+4QkfR240j+qXMWhfZQ70gc8xr6EOfY1JO9UwgV5e8J0pJSu 2qjd4ciq2AFp+ipZLyExm5XZlqn4LncSrUUE+8wnVh/el1JEDBepA1dxdRX4ycLyI1kQ/W8q0qDBu MhuO8W/A==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:59614) by pandora.armlinux.org.uk with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1rVxv3-0006Kg-2u; Fri, 02 Feb 2024 18:05:42 +0000 Received: from linux by shell.armlinux.org.uk with local (Exim 4.94.2) (envelope-from ) id 1rVxuy-0008VK-P4; Fri, 02 Feb 2024 18:05:36 +0000 Date: Fri, 2 Feb 2024 18:05:36 +0000 From: "Russell King (Oracle)" To: =?utf-8?B?QXLEsW7DpyDDnE5BTA==?= Cc: Daniel Golle , DENG Qingfang , Sean Wang , Andrew Lunn , Florian Fainelli , Vladimir Oltean , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Matthias Brugger , AngeloGioacchino Del Regno , mithat.guner@xeront.com, erkin.bozoglu@xeront.com, Bartel Eerdekens , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org Subject: Re: [PATCH net-next v3 1/7] net: dsa: mt7530: empty default case on mt7530_setup_port5() Message-ID: References: <20240202-for-netnext-mt7530-improvements-2-v3-0-63d5adae99ca@arinc9.com> <20240202-for-netnext-mt7530-improvements-2-v3-1-63d5adae99ca@arinc9.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=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Sender: Russell King (Oracle) On Fri, Feb 02, 2024 at 08:44:39PM +0300, Arınç ÜNAL wrote: > On 2.02.2024 14:40, Russell King (Oracle) wrote: > > While reviewing this change, but not related to it, I notice that this > > function sets the TX delay based on the RGMII interface mode. This isn't > > correct. I've explained why this is this many times in the past, but > > essentially it comes down to the model: > > > > > > phy-mode in NIC node Network driver PCB PHY > > rgmii no delays delays no delays > > rgmii-id no delays no delays tx/rx delays > > rgmii-txid no delays no delays tx delays > > rgmii-rxid no delays no delays rx delays > > > > Then we have rx-internal-delay-ps and tx-internal-delay-ps in the NIC > > node which define the RGMII delays at the local end and similar > > properties for the PHY node. > > > > > > So, if we take the view that, when a switch is connected to a NIC in > > RGMII mode, then the phy-mode specified delays still should not impact > > the local NIC. > > > > Now, for the switch, we specify the phy-mode in the port node as well. > > Consider the case of a switch port connected to a RGMII PHY. This has > > to operate in exactly the same way as a normal NIC - that is, the > > RGMII delays at the port should be ignored as it's the responsibility > > of a PHY. > > > > The final scenario to examine is the case of a RGMII switch port > > connected to a NIC. The NIC's phy-mode has no way to be communicated > > to DSA or vice versa, so neither phy-mode can impact the other side > > of the RGMII link, but should only place the link into RGMII mode. > > Given everything I've said above, the only way to configure RGMII > > delays is via the rx-internal-delay-ps and tx-internal-delay-ps > > properties. So, DSA drivers should _not_ be configuring their ports > > with RGMII delays based on the RGMII phy interface mode. > > > > The above is my purely logically reasoned point of view on this > > subject. Others may have other (to me completely illogical) > > interpretations that can only lead to interoperability issues. > > I will address this with the next patch series. Thank you for explaining it > in detail. This is a good time to point out not to rush with the next patch series, as my email will _likely_ provoke some additional discussion from Andrew and/or Vladimir. So please give it a few days (maybe around the middle of next week) to give them time to consider my email and respond. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!