Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755372AbcJPJzc (ORCPT ); Sun, 16 Oct 2016 05:55:32 -0400 Received: from ramses-pyramidenbau.de ([37.120.178.10]:37280 "EHLO mail.ramses-pyramidenbau.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753953AbcJPJza (ORCPT ); Sun, 16 Oct 2016 05:55:30 -0400 Subject: Re: [PATCH] spi: mark device nodes only in case of successful instantiation To: Geert Uytterhoeven References: <20161014193113.29275-1-ralf@ramses-pyramidenbau.de> Cc: Mark Brown , linux-spi , "linux-kernel@vger.kernel.org" , Geert Uytterhoeven , Wolfram Sang , Linux I2C From: Ralf Ramsauer Message-ID: <39e8d53a-a93d-feeb-044f-9b1b239dff21@ramses-pyramidenbau.de> Date: Sun, 16 Oct 2016 11:55:22 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3387 Lines: 96 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. Best Ralf > > 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