From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752481AbdGIQtm (ORCPT ); Sun, 9 Jul 2017 12:49:42 -0400 Received: from mail-oi0-f68.google.com ([209.85.218.68]:35141 "EHLO mail-oi0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752267AbdGIQtj (ORCPT ); Sun, 9 Jul 2017 12:49:39 -0400 Subject: Re: [PATCH] of_mdio: Fix broken PHY IRQ in case of probe deferral To: Geert Uytterhoeven , Andrew Lunn Cc: Geert Uytterhoeven , Rob Herring , Frank Rowand , Thomas Petazzoni , Sergei Shtylyov , "netdev@vger.kernel.org" , "devicetree@vger.kernel.org" , Linux-Renesas , "linux-kernel@vger.kernel.org" References: <1495112345-24795-1-git-send-email-geert+renesas@glider.be> <20170518193453.GB13759@lunn.ch> <08a89dd5-b707-8b8f-b8e1-e20b9ed630b7@gmail.com> From: Florian Fainelli Message-ID: <38cc7c65-e4ca-cb8a-f43b-ca53e87724cf@gmail.com> Date: Sun, 9 Jul 2017 09:49:35 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/02/2017 01:37 PM, Geert Uytterhoeven wrote: > On Tue, Jun 6, 2017 at 11:43 AM, Geert Uytterhoeven > wrote: >> On Tue, May 23, 2017 at 11:36 AM, Geert Uytterhoeven >> wrote: >>> On Fri, May 19, 2017 at 12:21 AM, Florian Fainelli wrote: >>>> On 05/18/2017 01:36 PM, Geert Uytterhoeven wrote: >>>>> On Thu, May 18, 2017 at 9:34 PM, Andrew Lunn wrote: >>>>>>>> This most certainly works fine in the simple case where you have one PHY >>>>>>>> hanging off the MDIO bus, now what happens if you have several? >>>>>>>> >>>>>>>> Presumably, the first PHY that returns EPROBE_DEFER will make the entire >>>>>>>> bus registration return EPROB_DEFER as well, and so on, and so forth, >>>>>>>> but I am not sure if we will be properly unwinding the successful >>>>>>>> registration of PHYs that either don't have an interrupt, or did not >>>>>>>> return EPROBE_DEFER. >>>>>>>> >>>>>>>> It should be possible to mimic this behavior by using the fixed PHY, and >>>>>>>> possibly the dsa_loop.c driver which would create 4 ports, expecting 4 >>>>>>>> fixed PHYs to be present. >>>>>>> >>>>>>> mdiobus_unregister(), called from of_mdiobus_register() on failure, >>>>>>> should do the unwinding, right? >>>>>>> >>>>>>> And when the driver is reprobed, all PHYs are reprobed, until they all >>>>>>> succeed. >>>>>> >>>>>> That is the theory. I looked at that while reviewing the patch. But >>>>>> this has probably not been tested in anger. It would be good to test >>>>>> this properly, with not just the first PHY returning -EPROBE_DEFER, to >>>>>> really test the unwind. >>>>> >>>>> Unfortunately I don't have a board with multiple PHYs, so I cannot test >>>>> that case. >>> >>> I tried adding a few dummy PHYs in DT, but that didn't work. >>> >>> So how can we proceed? >>> >>> I think the only way my patch can cause issues is because some systems >>> may rely on EPROBE_DEFER errors being ignored. >>> >>>>> Does unbinding/rebinding a network driver with multiple PHYs currently >>>>> work? Or module unload/reload? >>>> >>>> Usually there is a strict 1:1 mapping between a network device (not >>>> driver) and a PHY device, switch drivers however, would have multiple >>>> PHYs (one per port, aka net_deice). >>>> >>>> NB: binding and unbinding of PHYs is pretty broken at the moment though, >>>> because there is a complete disconnect between what the Ethernet MAC >>>> expects, and the state in which the PHY is. I had some patches to fix >>>> that, but this turned out to be playing whack-a-mole which I typically >>>> suck at. >>> >>> I didn't mean unbinding the PHY, but the network device. >>> Don't you have the same issue with the state of PHYs as left by the bootloader? >> >> Anyone who can test the behavior on an Ethernet device with multiple PHYs, >> e.g. by faking an -EPROBE_DEFER somewhere in the middle? >> >> I'd like to get this issue fixed in v4.13, to avoid a regression when migrating >> several systems to a new and better clock driver in v4.14, which will trigger >> EPROBE_DEFER. > > Ping? > > This patch fixes a real issue. It sure does fix a real issue, but I am really concerned about the inability to test this patch in a configuration where we have multiple PHY(s) or MDIO device(s) hanging off the same MDIO bus and one of those requesting an EPROBE_DEFER. I currently don't have a setup where I could exercise this, Andrew, do you? -- Florian