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 502F1C43458 for ; Tue, 30 Jun 2026 15:25:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id: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-Owner; bh=DmD+OzcP3hxAXs0Zz1yHPXf2Fl6f2W68HIV2dY8Fuvo=; b=sIPmWuPkpz0xZY8plk6TaHdC/K Rdioy5jxJ5I4TeD/aPvCDA4Yaeu8hOaz8+7Ll1Plowhc1ZlkOPWoNj/iHlrZ15oFOlpq7EYrIxEZN 9HSsANoGbga4gnE1upZqlH081BL8+oXE9Dxg/PV/RHomir4vD8F9r+WroYqmEORw/e3dBJydg+M8J lUPHid4jHblsvympvbPF52Ac6KEgvWvbcMpu3rOFitDIKRqlA59EiR2uYdoXcainq54SMVvFVUWkB iYw2DpLKWSYEGoP1kJdfKyVjeuuT0e1s958x+XmXZ070PbwtRjjmYjepNE9KHhpIKFhzUmiCX1Lm3 mAt8QL4Q==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1weaLN-0000000HN2t-0fO6; Tue, 30 Jun 2026 15:25:49 +0000 Received: from vps0.lunn.ch ([156.67.10.101]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1weaLK-0000000HN21-3LG3 for linux-arm-kernel@lists.infradead.org; Tue, 30 Jun 2026 15:25:48 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lunn.ch; s=20171124; h=In-Reply-To:Content-Transfer-Encoding:Content-Disposition: Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:From: Sender:Reply-To:Subject:Date:Message-ID:To:Cc:MIME-Version:Content-Type: Content-Transfer-Encoding:Content-ID:Content-Description:Content-Disposition: In-Reply-To:References; bh=DmD+OzcP3hxAXs0Zz1yHPXf2Fl6f2W68HIV2dY8Fuvo=; b=u8 YI+Vb20Zu09I/rIon96W7/QgPk4U+ZkBc/rYUj1VeEInlWZZ9zvHkyrlBBNVyPdsPoWLosuzvd2sO LlYNxr4IPV1a65A3sDas4YfkHmAOGmsdVWlzhds6kElu/PZfs9ganbPwKe/AnLhPV5BbcCY4BYCjG D41n0/HJS9Z2seg=; Received: from andrew by vps0.lunn.ch with local (Exim 4.94.2) (envelope-from ) id 1weaL4-00A0Yx-C3; Tue, 30 Jun 2026 17:25:30 +0200 Date: Tue, 30 Jun 2026 17:25:30 +0200 From: Andrew Lunn To: "Nazle Asmade, Muhammad Nazim Amirul" Cc: "dinguyen@kernel.org" , "maxime.chevallier@bootlin.com" , "rmk+kernel@armlinux.org.uk" , "krzk+dt@kernel.org" , "conor+dt@kernel.org" , "robh@kernel.org" , "davem@davemloft.net" , "edumazet@google.com" , "kuba@kernel.org" , "pabeni@redhat.com" , "andrew+netdev@lunn.ch" , "devicetree@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "netdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH 2/3] arm64: dts: socfpga: agilex5: Add SoCDK TSN Config2 board Message-ID: References: <20260630133108.27244-1-muhammad.nazim.amirul.nazle.asmade@altera.com> <20260630133108.27244-3-muhammad.nazim.amirul.nazle.asmade@altera.com> <347c50ed-234a-4f29-b63a-1e0010c6b09d@altera.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <347c50ed-234a-4f29-b63a-1e0010c6b09d@altera.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260630_082546_839407_9580A024 X-CRM114-Status: GOOD ( 21.77 ) 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: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Jun 30, 2026 at 02:39:50PM +0000, Nazle Asmade, Muhammad Nazim Amirul wrote: > On 30/6/2026 9:58 pm, Andrew Lunn wrote: > >> + * gmac1 is the TSN port. The MAC operates in GMII mode internally > >> + * while the PHY-side interface is RGMII, so mac-mode and phy-mode differ. > >> + */ > >> +&gmac1 { > >> + status = "okay"; > >> + phy-mode = "rgmii"; /* TX/RX clock delays provided by Agilex5 I/O hardware */ > > Could you provide more details about this. I want to understand the > > big picture. > > > > Normally we talk about the PCB providing the delays. This sounds like > > it is the FPGA? So i need convincing this is correct. > Hi Andrew, > > Thanks for your quick review and yes, it is the FPGA — specifically a > soft IP block in the FPGA fabric that implements the RGMII clock delays > and is configured before Linux boots via the FPGA bitstream. The driver > must not add additional delays on top. So it depends on how the converter block is described, but .... >From a big picture, MAC and PHY pair, it is the MAC which implements the delays. https://elixir.bootlin.com/linux/v6.15/source/Documentation/devicetree/bindings/net/ethernet-controller.yaml#L346 # There are a small number of cases where the MAC has hard coded # delays which cannot be disabled. The 'phy-mode' only describes the # PCB. The inability to disable the delays in the MAC does not change # the meaning of 'phy-mode'. It does however mean that a 'phy-mode' of # 'rgmii' is now invalid, it cannot be supported, since both the PCB # and the MAC and PHY adding delays cannot result in a functional # link. Thus the MAC should report a fatal error for any modes which # cannot be supported. When the MAC implements the delay, it must # ensure that the PHY does not also implement the same delay. So it # must modify the phy-mode it passes to the PHY, removing the delay it # has added. Failure to remove the delay will result in a # non-functioning link. Andrew --- pw-bot: cr