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=-8.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 0E951C433E0 for ; Mon, 8 Feb 2021 19:07:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B148464E5A for ; Mon, 8 Feb 2021 19:07:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236046AbhBHTGo (ORCPT ); Mon, 8 Feb 2021 14:06:44 -0500 Received: from vps0.lunn.ch ([185.16.172.187]:56082 "EHLO vps0.lunn.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235826AbhBHTEg (ORCPT ); Mon, 8 Feb 2021 14:04:36 -0500 Received: from andrew by vps0.lunn.ch with local (Exim 4.94) (envelope-from ) id 1l9Bou-004vFh-KW; Mon, 08 Feb 2021 20:03:36 +0100 Date: Mon, 8 Feb 2021 20:03:36 +0100 From: Andrew Lunn To: Serge Semin Cc: Serge Semin , Giuseppe Cavallaro , Alexandre Torgue , Jose Abreu , "David S. Miller" , Jakub Kicinski , Joao Pinto , Jose Abreu , Heiner Kallweit , Russell King , Alexey Malahov , Pavel Parkhomenko , Vyacheslav Mitrofanov , Maxime Coquelin , netdev@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 01/20] net: phy: realtek: Fix events detection failure in LPI mode Message-ID: References: <20210208140341.9271-1-Sergey.Semin@baikalelectronics.ru> <20210208140341.9271-2-Sergey.Semin@baikalelectronics.ru> <20210208174441.z4nnugkaadhmgnum@mobilestation> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210208174441.z4nnugkaadhmgnum@mobilestation> Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org > Hi Andrew, > > I honestly tried to find any doc with a glimpse of errata for RTL8211E > PHY, but with no luck. Official datasheet didn't have any info regarding > possible hw bugs too. Thus I had no choice but to find a fix of the > problem myself. > > It took me some time to figure out why the events weren't reported after > the very first link setup (turned out only a full HW reset clears the > PC1R.10 bit state). I thought it could have been connected with some > sleep/idle/power-safe mode. So I disabled the EEE initialization in the > STMMAC driver. It worked. Then I left the EEE mode enabled, but called the > phy_init_eee(phy, 0) method with "clk_stop_enable==0", so PHY wouldn't > stop RXC in LPI mode. And it wonderfully worked. Then I started to dig in > from another side. I left "RXC disable in LPI" mode enabled and tried to > figure out what was going on with the PHY when it stopped reporting events > just by reading from its CSR using phytool utility. It was curious to > discover that any attempt to read from any PHY register caused the problem > disappearance (LED2 started blinking, events got to be reported). Since I > did nothing but a mere reading from a random even EEE-unrelated register I > inferred that the problem must be in some HW/PHY bug. That's how I've got > to the patch introduced here. If you have any better idea what could be a > reason of that weird behavior I'd be glad to test it out on my device. It is a reasonable explanation, and a read should not do any harm. Reviewed-by: Andrew Lunn Andrew