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 4891D29BD87; Thu, 12 Feb 2026 10:28:36 +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=1770892117; cv=none; b=Za0WKwynnF/TOVLHG0mNB52mVe4urkWb2GGecHqScPA5XejzD/V4jYnfzOtJW5/4uHC6ai+a7KLTQjFvA5rTS3oBsxURgxvEQGDPsOiSfixLv8mq9WmQXBcSig1FBnovO7J5s/PWfpdZ+5anPgYakVXcgFwmRYdFiq8InvuSOQo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770892117; c=relaxed/simple; bh=dDixvmDCxBfjKGZUfcrZCK8jjMgfeSQI9VVri2MGUxA=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Yir5pMPnOp1IxcG1xaixzV+jgrHFsaWz0bqZfCpQf7edV0bthHxtFOqhHkmMUVZaLAiZj72KrvQVy5QnTcNWLDZMr/3YpYh5tqAUJ/HPGqUp7o3jQZT2+T8GEUyWqsHdiXkOudkhnnbT1AbsrsPovXW5wfxGCUdKfMHlCR+wJ7o= 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=1riGLJb1; 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="1riGLJb1" 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=xSFJcBfVZKp82+Db3xO54CWUoHlWgz8IeqJYSETUKnY=; b=1riGLJb1LrUTq2AMxJAEE3fPYe GGAhsHEa5SOZDT9rTt0biTAUn50DlKRNx0SI58Ki1gpElxnFzDbIcTz3KYeBe3ZjGL1UmNW86V+Q/ p5pUTRyhoyCSwsNJzEtmcqQvkPzP2RMr4aD7qeYVKI4ioPG0sQphqLV7Ej7U+LHbbLUqBKFhC87Ut RqYEns3IrdUHTgcItxWWeYTF4epkkC7RfnQcV0lVedVjPW8+NMnuNDdA1k5iOUTvK36Pr6+AxNjGG F2gQfai0V50HAyrXYgNq+ncht/5qgAPL3JGxKL7QFMnEQgOtSgbocJKaUuV9C+xvP+918nnj5CYB4 +5wbXcxw==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:49322) 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 1vqTvt-000000004QW-3erv; Thu, 12 Feb 2026 10:28:25 +0000 Received: from linux by shell.armlinux.org.uk with local (Exim 4.98.2) (envelope-from ) id 1vqTvr-000000004hn-3a12; Thu, 12 Feb 2026 10:28:23 +0000 Date: Thu, 12 Feb 2026 10:28:23 +0000 From: "Russell King (Oracle)" To: Vincent Guittot , Rob Herring Cc: vkoul@kernel.org, neil.armstrong@linaro.org, krzk+dt@kernel.org, conor+dt@kernel.org, ciprianmarian.costea@oss.nxp.com, s32@nxp.com, p.zabel@pengutronix.de, ghennadi.procopciuc@nxp.com, Ionut.Vicovan@nxp.com, linux-phy@lists.infradead.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, netdev@vger.kernel.org, horms@kernel.org, Frank.li@nxp.com Subject: Re: [PATCH 1/4 v2] dt-bindings: serdes: s32g: Add NXP serdes subsystem Message-ID: References: <20260203161917.1666696-1-vincent.guittot@linaro.org> <20260203161917.1666696-2-vincent.guittot@linaro.org> <20260210004011.GA2188625-robh@kernel.org> 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: <20260210004011.GA2188625-robh@kernel.org> Sender: Russell King (Oracle) On Mon, Feb 09, 2026 at 06:40:11PM -0600, Rob Herring wrote: > On Tue, Feb 03, 2026 at 05:19:14PM +0100, Vincent Guittot wrote: > > +description: | > > + The SerDes subsystem on S32G SoC Family includes two types of PHYs: > > + - One PCIe PHY: Supports various PCIe operation modes > > + - Two Ethernet Physical Coding Sublayer (XPCS) controllers > > + > > + SerDes operation mode selects the enabled PHYs and speeds. Clock frequency > > + must be adapted accordingly. Below table describes all possible operation > > + modes. > > + > > + Mode PCIe XPCS0 XPCS1 PHY clock Description > > + SGMII SGMII (MHz) > > + ------------------------------------------------------------------------- > > + 0 Gen3 N/A N/A 100 Single PCIe > > + 1 Gen2 1.25Gbps N/A 100 PCIe/SGMII > > + 2 Gen2 N/A 1.25Gbps 100 PCIe/SGMII > > + 3 N/A 1.25Gbps 1.25Gbps 100,125 SGMII > > + 4 N/A 3.125/1.25Gbps 3.125/1.25Gbps 125 SGMII > > + 5 Gen2 N/A 3.125Gbps 100 PCIe/SGMII > > Mixed tabs and spaces. Drop the tabs. > > What's not clear to me is do you have 2 or 4 lanes? > ... > > + nxp,sys-mode: > > + $ref: /schemas/types.yaml#/definitions/uint32 > > maximum: 5 > > Though isn't this redundant with the child nodes? You could use the > standard 'phy-mode' property in each child. phy-mode is ethernet, but the above is more than just ethernet. I've been wondering why a generic PHY driver needs to know this via DT when the generic PHY API has: phy_set_mode() / phy_set_mode_ext() - sets the type of the PHY and its submode (e.g. ethernet interface mode) phy_set_speed() phy_set_bus_width() Surely these are sufficient to describe what mode is required from the generic PHY, and the generic PHY driver can figure out whether the mode is permitted from the above table, programming the PHY as desired. For Ethernet, we don't call the 3.125Gbps "SGMII" using that term. We use SGMII strictly for Cisco SGMII, which runs at 1.25Gbps. 3.125Gbps single-lane serdes ethernet is not able to use Cisco SGMII inband signalling because running the underlying data rate with 10 or 100 symbol replications makes no sense. So we have decided to all this 2500BASE-X. If such a SerDes is connected to a SFP cage, then we support switching between 1.25Gbps and 3.125Gbps mode depending on the module inserted, which requires dynamic reconfiguration of the SerDes. What I'm saying is that describing a single mode covering several ports could make things difficult in the future, so make sure you think carefully. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!