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 X-Spam-Level: X-Spam-Status: No, score=-15.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7B171C2B9F4 for ; Fri, 25 Jun 2021 09:09:28 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 4C2076141C for ; Fri, 25 Jun 2021 09:09:28 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4C2076141C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=armlinux.org.uk Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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=a5Q681z8oM8HPZQb/gCFz2jjmADOr5k+ldfKVEwbmrw=; b=TdP728wGsKS2xV 4U0ruDZxthCqEWhz+j7w5hX/2C09P2aYxVLfsWO8aUU9/97LXTuFz+yh3p5orWidU9+1dxqTVt23i 832JbF19zKc1YfnjYsU4nE9jMXk0ntMCgAj5PEwacyxbGpL4wPtmSIxbLfKxbTilpysT0dfQR+Gc0 uF6hbXUi8fDYOfLI5goxugaLAAvymvVLwM247AT6xAs12LtmnpSk7QThLFH9mAdt8jVBRQY9zD9yJ 3Muogy00P5L0cZWevQ1WqEVwwHO8C6lkXJCgaMM+o9B6W5NAXZukDtiAVAfkhlZ889S+KfHvJc486 vLLPOv2P+nT0m/DEM5uw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1lwhnx-000ZiM-96; Fri, 25 Jun 2021 09:07:18 +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 1lwhMN-000QTC-3R for linux-arm-kernel@lists.infradead.org; Fri, 25 Jun 2021 08:38:49 +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-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-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=y/xQbMyMnMxZ5Gql4eu4zBlccrgde0Q2Cbp1fMJpM/0=; b=h8GK8ea9YmRjCkYMkRYtPHWlU GICBKOokMCyNagLzYbZyTBBizq8nPfm9GX20I47WwD/UkrvyGwu6zik4FK+USO0YdswhCCxe35IJX lMY+hj+PpyqCiyGBnuwuq05W0et8+ZaweQUJZYtsaPYhGV5Wt4NhSF30mLHbCrmNCp8I0dpmbUEaa +X3kN1pYPogAwRc/X5IRiO/gbaD17IIckAXJjk519u4SPBafp7tzp0W2PwZwk85fkSxxwG5XV0zKI 2aqVBP+kUfG4j0/JpPHJo9RWO6JBjkwj7g3mHKBB395+Kf4J4royVR96DBfZ/q67hXJ/uJwtOjH3b 3uWL79wTQ==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:45336) by pandora.armlinux.org.uk with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1lwhMG-0000NX-LP; Fri, 25 Jun 2021 09:38:40 +0100 Received: from linux by shell.armlinux.org.uk with local (Exim 4.92) (envelope-from ) id 1lwhMG-0006WW-6w; Fri, 25 Jun 2021 09:38:40 +0100 Date: Fri, 25 Jun 2021 09:38:40 +0100 From: "Russell King (Oracle)" To: Maxime Chevallier Cc: Shawn Guo , Rob Herring , Andrew Lunn , thomas.petazzoni@bootlin.com, herve.codina@bootlin.com, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] ARM: dts: imx6qdl-sr-som: Increase the PHY reset duration to 10ms Message-ID: <20210625083840.GS22278@shell.armlinux.org.uk> References: <20210625083051.3691737-1-maxime.chevallier@bootlin.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210625083051.3691737-1-maxime.chevallier@bootlin.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210625_013848_195340_0226C74A X-CRM114-Status: GOOD ( 25.71 ) 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="iso-8859-1" Content-Transfer-Encoding: quoted-printable Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Jun 25, 2021 at 10:30:51AM +0200, Maxime Chevallier wrote: > The datasheet for the AR803x PHY present on this SoM recommends that the > reset line is asserted low for 10ms, so that the PHY has time to > properly reset the internal blocks. > = > The previous value of 2ms was found to be problematic on some setups, > causing intermittent issues where the PHY would be unresponsive > every once in a while on some sytems, with a low occurence (it typically > took around 30 consecutive reboots to encounter the issue). > = > Bumping the delay to the 10ms recommended value makes the issue > dissapear, with more than 2500 consecutive reboots performed without the > issue showing-up. This isn't actually what the datasheet says, which is: Input clock including the crystal and external input clock should be stable for at least 1ms before RESET can be deasserted. When using crystal, the clock is generated internally after power is stable. For a reliable power on reset, suggest to keep asserting the reset low long enough (10ms) to ensure the clock is stable and clock-to-reset 1ms requirement is satisfied. The 10ms duration you quote is the _power on reset_ duration, and in those circumstances, there is a delay before the required clocks will be stable. This is not a power on reset scenario - the power was applied long ago by the time the kernel starts booting, and XI clock would have been running. So, I think the commit message which seems to be claiming that the reset line always needs to be asserted for 10ms is not entirely accurate. > = > Fixes: 208d7baf8085 ("ARM: imx: initial SolidRun HummingBoard support") > Signed-off-by: Maxime Chevallier > Tested-by: Herv=E9 Codina > --- > arch/arm/boot/dts/imx6qdl-sr-som.dtsi | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > = > diff --git a/arch/arm/boot/dts/imx6qdl-sr-som.dtsi b/arch/arm/boot/dts/im= x6qdl-sr-som.dtsi > index 0ad8ccde0cf8..a54dafce025b 100644 > --- a/arch/arm/boot/dts/imx6qdl-sr-som.dtsi > +++ b/arch/arm/boot/dts/imx6qdl-sr-som.dtsi > @@ -54,7 +54,7 @@ &fec { > pinctrl-names =3D "default"; > pinctrl-0 =3D <&pinctrl_microsom_enet_ar8035>; > phy-mode =3D "rgmii-id"; > - phy-reset-duration =3D <2>; > + phy-reset-duration =3D <10>; > phy-reset-gpios =3D <&gpio4 15 GPIO_ACTIVE_LOW>; > status =3D "okay"; > = > -- = > 2.25.4 > = > = -- = 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