From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 4CCF2ECAAD3 for ; Thu, 15 Sep 2022 10:09:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To: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-Owner; bh=IDoKDZducUwUV+sHrDY5qTSNY8LNJ3KD0+RoYdwAguY=; b=Lha+j5/umG9aH9 27Q8lnnT4DQWDbzUU/cSJ7WJDv/u9GJpQzI2wfWYR5Z5ezKFCcwqw6zb7ExL1Sm3Lwz8g2/+4wiKD 6fdZcNcUwON0qDJp6SSvt1M7kAeYo47387XTQViJ4oicju0djhhwj2BN4oorHLKKa8uvaNQS9S0Y0 N+DUWsS7dWWNLkxAjTd+DmLqZyHD/KNhvr8eN49zLuGHodasfUnpYD4BEA2xA1jDiBYbZCBJqgMLt 8ZGilFDubOHARdAuxCp+YZ0uxjFCmwuGV0GU90RU5xcqsXhcdqXZY5Escezz1yufhxoCLSSONQDYS V8G5n0CzdMhLFw5ERUEg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1oYln5-006AE6-7g; Thu, 15 Sep 2022 10:08:15 +0000 Received: from pandora.armlinux.org.uk ([2001:4d48:ad52:32c8:5054:ff:fe00:142]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1oYln1-0068OQ-Ik for linux-arm-kernel@lists.infradead.org; Thu, 15 Sep 2022 10:08:13 +0000 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=lEcKAUl8uQYq+qOdV2UzEHdm6WUdIBi8uUUItFAWIow=; b=T6UvT04L11Ek3OkV3KRUdqTMBf yjoZrmtDvQ/81H8keWnDPKiXL76sDSLOBJ/WfNnjyQb7NlTMTbs14Ev/debcGweG8qatDja/Z9NAg DfVhm4dbsGOXdw4xMZEOk3xrZIHo8u3uvFTrZs5N5RRvxVwSQTQK5yqXcgTnr73EPBQZ9AYBeP3cD TLrF5WrwMvGqMC8wXFMc1kSduuCXbFybJzrtAxyvyVLA+dx0Ij1nCtWyzYOPrAcMvjg/n0/53f1O1 UY156jdceqeLqbhOCyCRWuj4xrkSh/UhFqjcn+sf42oWgwlZYrdrbzGPSVQ47uRBidfylhiOiixiI CB0/Y0bw==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:34344) by pandora.armlinux.org.uk with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1oYlmJ-0005RV-Vj; Thu, 15 Sep 2022 11:07:28 +0100 Received: from linux by shell.armlinux.org.uk with local (Exim 4.94.2) (envelope-from ) id 1oYlmG-0002Wd-0t; Thu, 15 Sep 2022 11:07:24 +0100 Date: Thu, 15 Sep 2022 11:07:23 +0100 From: "Russell King (Oracle)" To: Siddharth Vadapalli Cc: davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, robh+dt@kernel.org, krzysztof.kozlowski@linaro.org, krzysztof.kozlowski+dt@linaro.org, vladimir.oltean@nxp.com, grygorii.strashko@ti.com, vigneshr@ti.com, nsekhar@ti.com, netdev@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kishon@ti.com Subject: Re: [PATCH 5/8] net: ethernet: ti: am65-cpsw: Add support for fixed-link configuration Message-ID: References: <20220914095053.189851-1-s-vadapalli@ti.com> <20220914095053.189851-6-s-vadapalli@ti.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220915_030811_643301_D7EA17EA X-CRM114-Status: GOOD ( 24.07 ) 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: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi, On Thu, Sep 15, 2022 at 02:58:52PM +0530, Siddharth Vadapalli wrote: > Hello Russell, > > On 14/09/22 21:39, Russell King (Oracle) wrote: > > On Wed, Sep 14, 2022 at 03:20:50PM +0530, Siddharth Vadapalli wrote: > >> Check for fixed-link in am65_cpsw_nuss_mac_config() using struct > >> am65_cpsw_slave_data's phy_node property to obtain fwnode. Since > >> am65_cpsw_nuss_mac_link_up() is not invoked in fixed-link mode, perform > >> the relevant operations in am65_cpsw_nuss_mac_config() itself. > > > > Further to my other comments, you also fail to explain that, when in > > fixed-link SGMII mode, you _emulate_ being a PHY - which I deduce > > since you are sending the duplex setting and speed settings via the > > SGMII control word. Also, as SGMII was invented for a PHY to be able > > to communicate the media negotiation resolution to the MAC, SGMII > > defines that the PHY fills in the speed and duplex information in > > the control word to pass it to the MAC, and the MAC acknowledges this > > information. There is no need (and SGMII doesn't permit) the MAC to > > advertise what it's doing. > > > > Maybe this needs to be explained in the commit message? > > I had tested SGMII fixed-link mode using a bootstrapped ethernet layer-1 > PHY. Based on your clarification in the previous mails that there is an > issue with the fixed-link mode which I need to debug, I assume that what > you are referring to here also happens to be a consequence of that. > Please let me know if I have misunderstood what you meant to convey. I think what you're saying is that you have this setup: ethernet MAC <--SGMII link--> ethernet PHY <---> media which you are operating in fixed link mode? >From the SGMII specification: "This is achieved by using the Auto- Negotiation functionality defined in Clause 37 of the IEEE Specification 802.3z. Instead of the ability advertisement, the PHY sends the control information via its tx_config_Reg[15:0] as specified in Table 1 whenever the control information changes. Upon receiving control information, the MAC acknowledges the update of the control information by asserting bit 14 of its tx_config_reg{15:0] as specified in Table 1." For the control word sent from the MAC to the PHY, table 1 specifies a value of 0x4001. All the zero bits in that word which are zero are marked as "Reserved for future use." There are no fields for speed and duplex in this acknowledgement word to the PHY. I hope this clears up my point. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last! _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel