Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932185AbcKJIqp (ORCPT ); Thu, 10 Nov 2016 03:46:45 -0500 Received: from mail-it0-f67.google.com ([209.85.214.67]:33320 "EHLO mail-it0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751582AbcKJIqo (ORCPT ); Thu, 10 Nov 2016 03:46:44 -0500 MIME-Version: 1.0 In-Reply-To: References: <27296716.H9VWo8ShOm@vostro.rjw.lan> <13957403.ZrB4mMbICz@vostro.rjw.lan> <2715729.9U1nlcpFb3@vostro.rjw.lan> <20161026111902.GA6447@wunner.de> <20161027152551.GA15718@kroah.com> <20161107212250.GH1764@wotan.suse.de> From: Geert Uytterhoeven Date: Thu, 10 Nov 2016 09:46:42 +0100 X-Google-Sender-Auth: 0yNH5yoxNxy7-Y7qJdmAzqO16ow Message-ID: Subject: Re: [PATCH v5 2/5] driver core: Functional dependencies tracking support To: "Luis R. Rodriguez" Cc: "Rafael J. Wysocki" , Greg Kroah-Hartman , Lukas Wunner , "Rafael J. Wysocki" , Linux PM list , Alan Stern , Linux Kernel Mailing List , Tomeu Vizoso , Mark Brown , Marek Szyprowski , Kevin Hilman , Ulf Hansson , Laurent Pinchart , Lars-Peter Clausen , Grant Likely , Mauro Carvalho Chehab , Dmitry Torokhov , Andrzej Hajda Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by mail.home.local id uAA8kp2x021671 Content-Length: 2246 Lines: 49 On Thu, Nov 10, 2016 at 1:59 AM, Luis R. Rodriguez wrote: > On Wed, Nov 9, 2016 at 4:43 PM, Rafael J. Wysocki wrote: >> On Mon, Nov 7, 2016 at 10:22 PM, Luis R. Rodriguez wrote: >>> As clarified by Rafael at Plumbers, this functional dependencies >>> framework assumes your driver / subsystem supports deferred probe, >> >> It isn't particularly clear what you mean by "support" here. > > I noted some folks had reported issues, and you acknowledged that if > deferred probe was used in some drivers and if this created an issue > the same issue would be seen with this framework. AFAICT there are two > possible issues to consider: > > 1) the one Geert Uytterhoeven noted. Again I'll note what he had mentioned [0]. > > "Some drivers / subsystems don’t support deferred probe yet, such failures > usually don’t blow up, but cause subtle malfunctioning. Example, an Ethernet > phy could not get its interrupt as the primary IRQ chip had not been probed > yet, it reverted to polling though. Sub-optimal." [0] > > [0] https://lists.linuxfoundation.org/pipermail/ksummit-discuss/2016-August/003425.html > > Geert can you provide more details? Issue reported in "of_mdiobus_register_phy() and deferred probe" (http://lkml.iu.edu/hypermail/linux/kernel/1510.2/05770.html) Key point is: "However, of_mdiobus_register_phy() uses irq_of_parse_and_map(), which plainly ignores EPROBE_DEFER, and it just continues." At that time, the PHY driver fell back to polling, but as of commit d5c3d8465 ("net: phy: Avoid polling PHY with PHY_IGNORE_INTERRUPTS") that's no longer the case, and now the PHY fails to work completely. Workaround is "[PATCH v2] irqchip/renesas-irqc: Postpone driver initialization" (https://www.spinics.net/lists/netdev/msg403325.html), which seems to have sparked some interest in fixing the issue for good ;-) Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds