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 CF0A8C369C2 for ; Fri, 25 Apr 2025 14:13:38 +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:Content-Transfer-Encoding: Content-Type:MIME-Version:References:In-Reply-To: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=nCEyDT0nGnZmgHn2zf2dWe+DqNKcKS+VLDZKV6s8w9k=; b=0CwLLjVpkY6EGrh7cJLiMIymxu gfzKLk189o5/LcirU56v9n6DuBOGuYeJyYIVfzAzgD/hC9xr815xFiV++OF+IMSOqM/mxe1fSWeFT bi9sWrQskOUgng8RwgxXxGbO/a7zXiUYkDxec/3p4yTio2+N2bcr51bFRGgSkIQCFnswpaTMnlIu/ hISI5zkzObwD3YUSdDK5vVbracOBUPEVSgWPM4ESl65HFZLw8wRLq6AKfOoA6A/gf3aJNPfhdWMSc VYoZQa7/8bdsbLlQwiXjKJqdPOBTnIBxWnxSNSLw2vE1kAXHrnWJPBjrwEG3FhGGmurWIRdbWkkxX 1yr9YplQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1u8Jo3-0000000HOcG-05rI; Fri, 25 Apr 2025 14:13:31 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1u8J15-0000000HGUM-2ewb for linux-arm-kernel@lists.infradead.org; Fri, 25 Apr 2025 13:22:56 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 82A88106F; Fri, 25 Apr 2025 06:22:49 -0700 (PDT) Received: from donnerap.manchester.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 67B103F59E; Fri, 25 Apr 2025 06:22:52 -0700 (PDT) Date: Fri, 25 Apr 2025 14:22:50 +0100 From: Andre Przywara To: Andrew Lunn Cc: Jernej =?UTF-8?B?xaBrcmFiZWM=?= , Yixun Lan , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Chen-Yu Tsai , Samuel Holland , Maxime Ripard , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-sunxi@lists.linux.dev, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, clabbe.montjoie@gmail.com Subject: Re: [PATCH 4/5] arm64: dts: allwinner: a527: add EMAC0 to Radxa A5E board Message-ID: <20250425142250.006a029d@donnerap.manchester.arm.com> In-Reply-To: <3681181a-0fbb-4979-9a7e-b8fe5c1b7c3c@lunn.ch> References: <20250423-01-sun55i-emac0-v1-0-46ee4c855e0a@gentoo.org> <4ba3e7b8-e680-40fa-b159-5146a16a9415@lunn.ch> <20250424150037.0f09a867@donnerap.manchester.arm.com> <4643958.LvFx2qVVIh@jernej-laptop> <20250424235658.0c662e67@minigeek.lan> <3681181a-0fbb-4979-9a7e-b8fe5c1b7c3c@lunn.ch> Organization: ARM X-Mailer: Claws Mail 3.18.0 (GTK+ 2.24.32; aarch64-unknown-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250425_062255_722191_55739331 X-CRM114-Status: GOOD ( 20.80 ) 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 Fri, 25 Apr 2025 04:01:30 +0200 Andrew Lunn wrote: > > Ah, right, I dimly remembered there was some hardware setting, but your > > mentioning of those strap resistors now tickled my memory! > > > > So according to the Radxa board schematic, RGMII0-RXD0/RXDLY is pulled > > up to VCCIO via 4.7K, while RGMII0-RXD1/TXDLY is pulled to GND (also via > > 4K7). According to the Motorcom YT8531 datasheet this means that RX > > delay is enabled, but TX delay is not. > > The Avaota board uses the same setup, albeit with an RTL8211F-CG PHY, > > but its datasheet confirms it uses the same logic. > > > > So does this mean we should say rgmii-rxid, so that the MAC adds the TX > > delay? Does the stmmac driver actually support this? I couldn't find > > this part by quickly checking the code. > > No. It is what the PCB provides which matters. A very small number of > PCB have extra long clock lines to add the 2ns delay. Those boards > should use 'rgmii'. All other boards should use rgmii-id, meaning the > delays need to be provided somewhere else. Typically it is the PHY > which adds the delays. > > The strapping should not matter, the PHY driver will override that. So > 'rgmii-id' should result in the PHY doing the basis 2ns in both > directions. The MAC DT properties then add additional delays, which i > consider fine tuning. Most systems don't actually need fine tuning, > but the YT8531 is funky, it often does need it for some reason. Ah, many thanks for the explanation, that clears that up! I read something about the MAC adding delays, which confused me, but what you say now makes sense. Thanks! Andre.