Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936562AbcJQTUt (ORCPT ); Mon, 17 Oct 2016 15:20:49 -0400 Received: from mail-qk0-f195.google.com ([209.85.220.195]:36399 "EHLO mail-qk0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934593AbcJQTUk (ORCPT ); Mon, 17 Oct 2016 15:20:40 -0400 Subject: Re: [PATCH] spi: mark device nodes only in case of successful instantiation Mime-Version: 1.0 (Mac OS X Mail 9.3 \(3124\)) Content-Type: text/plain; charset=utf-8 From: Pantelis Antoniou In-Reply-To: <39e8d53a-a93d-feeb-044f-9b1b239dff21@ramses-pyramidenbau.de> Date: Mon, 17 Oct 2016 22:20:47 +0300 Cc: Geert Uytterhoeven , Mark Brown , linux-spi , "linux-kernel@vger.kernel.org" , Geert Uytterhoeven , Wolfram Sang , Linux I2C Message-Id: <33118B65-9BF4-45AF-AC55-B44BECB5BBD1@gmail.com> References: <20161014193113.29275-1-ralf@ramses-pyramidenbau.de> <39e8d53a-a93d-feeb-044f-9b1b239dff21@ramses-pyramidenbau.de> To: Ralf Ramsauer X-Mailer: Apple Mail (2.3124) 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 u9HJKqli005236 Content-Length: 3721 Lines: 110 Hi Ralf, > On Oct 16, 2016, at 12:55 , Ralf Ramsauer wrote: > > Hi Geert, > > On 10/16/2016 10:49 AM, Geert Uytterhoeven wrote: >> Hi Ralf, >> >> (Cc i2c) >> >> On Fri, Oct 14, 2016 at 9:31 PM, Ralf Ramsauer >> wrote: >>> Instantiated SPI device nodes are marked with OF_POPULATE. This was >>> introduced in bd6c164. On unloading, loaded device nodes will of course >>> be unmarked. The problem are nodes the fail during initialisation: If a >>> node failed during registration, it won't be unloaded and hence never be >>> unmarked again. >>> >>> So if a SPI driver module is unloaded and reloaded, it will skip nodes >>> that failed before. >>> >>> Skip device nodes that are already populated and mark them only in case >>> of success. >>> >>> Fixes: bd6c164 ("spi: Mark instantiated device nodes with OF_POPULATE") >>> Signed-off-by: Ralf Ramsauer >>> Cc: Geert Uytterhoeven >>> --- >>> Hi, >>> >>> imagine the following situation: you loaded a spi driver as module, but >>> it fails to instantiate, because of some reasons (e.g. some resources, >>> like gpios, might be in use in userspace). >>> >>> When reloading the driver, _all_ nodes, including previously failed >>> ones, should be probed again. This is not the case at the moment. >>> Current behaviour only re-registers nodes that were previously >>> successfully loaded. >>> >>> This small patches fixes this behaviour. I stumbled over this while >>> working on a spi driver. >> >> Thanks for your patch! >> >>> drivers/spi/spi.c | 7 +++++-- >>> 1 file changed, 5 insertions(+), 2 deletions(-) >>> >>> diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c >>> index 200ca22..f96a04e 100644 >>> --- a/drivers/spi/spi.c >>> +++ b/drivers/spi/spi.c >>> @@ -1604,12 +1604,15 @@ static void of_register_spi_devices(struct spi_master *master) >>> return; >>> >>> for_each_available_child_of_node(master->dev.of_node, nc) { >>> - if (of_node_test_and_set_flag(nc, OF_POPULATED)) >>> + if (of_node_check_flag(nc, OF_POPULATED)) >>> continue; >>> spi = of_register_spi_device(master, nc); >>> - if (IS_ERR(spi)) >>> + if (IS_ERR(spi)) { >>> dev_warn(&master->dev, "Failed to create SPI device for %s\n", >>> nc->full_name); >>> + continue; >>> + } >>> + of_node_set_flag(nc, OF_POPULATED); >> >> I think it's safer to keep the atomic test-and-set, but clear the flag on >> failure, cfr. of_platform_device_create_pdata() and of_amba_device_create(). > Ack, no prob. Let me change this in the next version. >> >> Shouldn't of_spi_notify() be fixed, too? > Right, that's almost the same path. >> >> The same issue exists for i2c in of_i2c_register_devices() and of_i2c_notify(), >> which is what I had used as an example. > Good old c&p ;-) > I'll fix and test that tomorrow and come back with two patches, as it > touches different subsystems. > Thanks for this. This is a very rare case that’s easy to slip through. It is good to be consistent :) > Best > Ralf >> Regards — Pantelis >> 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 >> > > > -- > Ralf Ramsauer > GPG: 0x8F10049B