From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anssi Hannula Subject: Re: [PATCH] net: macb: do not disable MDIO bus when closing interface Date: Fri, 10 Aug 2018 09:22:05 +0300 Message-ID: References: <20180808121901.10264-1-anssi.hannula@bitwise.fi> <425ed5af-eac2-a58b-b6ca-f022a80367e4@microchip.com> <3c3a606e-b3e1-41fc-fcd8-7b98968fd06b@bitwise.fi> <20180809151433.GB20006@lunn.ch> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Cc: Claudiu Beznea , Nicolas Ferre , "David S. Miller" , netdev@vger.kernel.org To: Andrew Lunn Return-path: Received: from mail.bitwise.fi ([109.204.228.163]:48540 "EHLO mail.bitwise.fi" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725746AbeHJIud (ORCPT ); Fri, 10 Aug 2018 04:50:33 -0400 In-Reply-To: <20180809151433.GB20006@lunn.ch> Content-Language: en-US Sender: netdev-owner@vger.kernel.org List-ID: On 9.8.2018 18:14, Andrew Lunn wrote: > Hi Anssi Hi! >> macb_reset_hw() is called in init path too, though, so maybe clearing >> all bits is intentional / wanted to get the controller to a known state, >> even though the comment only mentions TX/RX? > You need to be careful here. Once of_mdiobus_register() is called, the > MDIO should be usable. If you happen to have an Ethernet switch on the > bus, it could be probed then. The DSA driver will start using the bus. > Or if you have a second PHY, connected to some other MAC, it could be > used by the other MAC. This all happens in the macb_probe function. > > Sometime later, the interface will be up'ed. At this point macb_open() > is called, which calls macb_init_hw(), which calls > macb_reset_hw(). What you don't want happening is changes to the NCR > at this point breaking an MDIO transaction which might be going on. > > Ideally, the MPE should be enabled before of_mdiobus_register(), and > left alone until mdiobus_unregister() is called in macb_remove(). Yep, fixing the use case of having PHYs of other MACs is why I wrote the patch :) Currently the reset code disables MPE while other MACs are using PHYs on the bus. -- Anssi Hannula / Bitwise Oy +358 503803997