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=-5.3 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 C0CD0C07E9B for ; Fri, 9 Jul 2021 15:54:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A852161182 for ; Fri, 9 Jul 2021 15:54:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232385AbhGIP5b (ORCPT ); Fri, 9 Jul 2021 11:57:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51524 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231976AbhGIP5a (ORCPT ); Fri, 9 Jul 2021 11:57:30 -0400 Received: from pandora.armlinux.org.uk (pandora.armlinux.org.uk [IPv6:2001:4d48:ad52:32c8:5054:ff:fe00:142]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0355BC0613DD; Fri, 9 Jul 2021 08:54:46 -0700 (PDT) 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=Jsw/ngtLTGz+rX9IOc4ToB/qHLSDIH6IoMbYjr26N84=; b=BQWj9lG9sPMHYq+SZocXjF36l Kf686SWmfxqe644Vwy0kAPJrFS1O4pNRSDP5COdHLWNQqQHVDp3FYsVLpco1PYV4okgZinEG7jpr9 79OHDMvu3/WGmycSN58LFuNV8lgyYAfQATMiNNC3mK8YywFFTNZuyZU2hPUoMn3xuL+yZGBANt2xq bzTjSEVEkoZOyEX6IoJlgwoUynR7IqpxlpwiEsyJkk8dAKQsHLvQd+IGkizaBJuUWPdUBum3X8x7b tc6R3nqnwy28k69fLtvkoJkAoa+5xelUNDK27HNBTcSxJNVkN9b8JU1c8unYxoInf8g2xfbZOdA+u bVualvlaQ==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:45920) by pandora.armlinux.org.uk with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1m1spw-000200-Sn; Fri, 09 Jul 2021 16:54:44 +0100 Received: from linux by shell.armlinux.org.uk with local (Exim 4.92) (envelope-from ) id 1m1spw-00055L-Ao; Fri, 09 Jul 2021 16:54:44 +0100 Date: Fri, 9 Jul 2021 16:54:44 +0100 From: "Russell King (Oracle)" To: Geert Uytterhoeven Cc: Andrew Lunn , Heiner Kallweit , netdev , Linux-Renesas Subject: Re: PHY reset may still be asserted during MDIO probe Message-ID: <20210709155444.GB22278@shell.armlinux.org.uk> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: Russell King (Oracle) Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Fri, Jul 09, 2021 at 05:33:36PM +0200, Geert Uytterhoeven wrote: > Hi all, > > I'm investigating a network failure after kexec on the Renesas Koelsch > and Salvator-XS development boards, using the sh-eth or ravb driver. Personally, I've never liked the reset support at PHY device level due to problems like the one you've identified here. I've tended to use the bus-level reset in preference to the PHY-level reset, particularly because when you have multiple PHYs on the bus all sharing a common reset, it seems to be the most sensible approach - and I see a single PHY as no different from multiple PHYs on the bus. However, I can see the argument for using the PHY level, but as you note, that can create chicken and egg issues. I'm not entirely sure why we decide to hold a PHY in reset when we've found it but not started to make use of it - we don't do that with other devices in the system. Why are PHYs special? -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!