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 F1878C369CB for ; Thu, 24 Apr 2025 00:58:41 +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=3Z01g9mp1eyyFtluc5GyteUbLs/S90EnYtjJKxUTeL4=; b=qXOUJ2J5pRvQxopcI3fMqDThqD kEDc4wetd4c171tdiYYFFyQsnOzkpNI4uvBe6Ha9u9wkfX6TxIabicWzAIEHOb5Z9yQl9+a48dYBe r5FKh7ryc9LItl/IaFTuwahjfY3IfP0XJKUBiiFr9Gc5uAjSR9fPC1e2GS9G+cadd+PCve+DEkXFw ZFV41C9hVoSVechw1D/t9t/eFg1YnhYqUZym7pYIzE8/j4TqNngGTAAsc23ysbg1kBMJLLtcce6cn hwuMTvGmI/RTD09nEaiLcd1bUlxPZuRL7jHZ8ZYogoUecAmAAybadzU2JOY0KsfLQ0JLGpHSllXo9 bUEWxVQg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1u7kvB-0000000CSQb-36Rs; Thu, 24 Apr 2025 00:58:33 +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 1u7kgx-0000000CQVm-2NpK for linux-arm-kernel@lists.infradead.org; Thu, 24 Apr 2025 00:43:53 +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 073311063; Wed, 23 Apr 2025 17:43:43 -0700 (PDT) Received: from minigeek.lan (usa-sjc-mx-foss1.foss.arm.com [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 812703F59E; Wed, 23 Apr 2025 17:43:45 -0700 (PDT) Date: Thu, 24 Apr 2025 01:42:41 +0100 From: Andre Przywara To: Andrew Lunn Cc: Yixun Lan , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Chen-Yu Tsai , Jernej Skrabec , 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 Subject: Re: [PATCH 4/5] arm64: dts: allwinner: a527: add EMAC0 to Radxa A5E board Message-ID: <20250424014120.0d66bd85@minigeek.lan> In-Reply-To: References: <20250423-01-sun55i-emac0-v1-0-46ee4c855e0a@gentoo.org> <20250423-01-sun55i-emac0-v1-4-46ee4c855e0a@gentoo.org> Organization: Arm Ltd. X-Mailer: Claws Mail 4.2.0 (GTK 3.24.31; x86_64-slackware-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-20250423_174351_651889_1EA3EAD8 X-CRM114-Status: GOOD ( 12.89 ) 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 Wed, 23 Apr 2025 18:58:37 +0200 Andrew Lunn wrote: Hi, > > +&emac0 { > > + phy-mode = "rgmii"; > > Does the PCB have extra long clock lines in order to provide the > needed 2ns delay? I guess not, so this should be rgmii-id. That's a good point, and it probably true. > > > + phy-handle = <&ext_rgmii_phy>; > > + > > + allwinner,tx-delay-ps = <300>; > > + allwinner,rx-delay-ps = <400>; > > These are rather low delays, since the standard requires 2ns. Anyway, > once you change phy-mode, you probably don't need these. Those go on top of the main 2ns delay, I guess to accommodate some skew between the RX and TX lines, or to account for extra some PCB delay between clock and data? The vendor BSP kernels/DTs program those board specific values, so we have been following suit for a while, for the previous SoCs as well. I just tried, it also works with some variations of those values, but setting tx-delay to 0 stops communication. Cheers, Andre