From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757547AbcIONfu (ORCPT ); Thu, 15 Sep 2016 09:35:50 -0400 Received: from relay1.mentorg.com ([192.94.38.131]:52602 "EHLO relay1.mentorg.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754290AbcIONfe (ORCPT ); Thu, 15 Sep 2016 09:35:34 -0400 Subject: Re: Crashing 'kzm' target in next-20160913 due to 'gpio: mxc: shift gpio_mxc_init() to subsys_initcall level' To: Guenter Roeck , Shawn Guo , =?UTF-8?Q?Uwe_Kleine-K=c3=b6nig?= References: <9befb559-499a-dd70-cd44-60d5fce2e5d6@roeck-us.net> CC: "linux-kernel@vger.kernel.org" , Greg Kroah-Hartman , Shawn Guo , Linus Walleij From: Vladimir Zapolskiy Message-ID: <99993063-6692-0870-12fa-64cf13d507f6@mentor.com> Date: Thu, 15 Sep 2016 16:35:04 +0300 User-Agent: Mozilla/5.0 (X11; Linux i686; rv:45.0) Gecko/20100101 Icedove/45.2.0 MIME-Version: 1.0 In-Reply-To: <9befb559-499a-dd70-cd44-60d5fce2e5d6@roeck-us.net> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [137.202.0.76] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Guenter, On 09/14/2016 06:20 AM, Guenter Roeck wrote: > Hi Vladimir, > > your commit e188cbf7564f ("gpio: mxc: shift gpio_mxc_init() to subsys_initcall level") > in -next causes the following crash when running the 'kzm' target (and most likely > the real thing) with qemu. > > [ 1.211426] Unable to handle kernel NULL pointer dereference at virtual address 0000000c > [ 1.211600] pgd = c0004000 > [ 1.211680] [0000000c] *pgd=00000000 > [ 1.212067] Internal error: Oops: 5 [#1] SMP ARM > [ 1.212245] Modules linked in: > [ 1.212542] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.8.0-rc6-next-20160913 #1 > [ 1.212671] Hardware name: Kyoto Microcomputer Co., Ltd. KZM-ARM11-01 > [ 1.212825] task: c6848000 task.stack: c683e000 > [ 1.213231] PC is at platform_get_irq+0xc0/0xe8 > > See http://kerneltests.org/builders/qemu-arm-next/builds/525/steps/qemubuildcommand/logs/stdio > for a complete log. > > Problem is quite subtle. The change causes the gpio driver to be installed later. > As a result, kzm_init_smsc9118() fails to initialize the gpio pins correctly. > gpio_request() in that function returns -EPROBE_DEFER, which is ignored, > gpio_to_irq() then returns -22 which is unconditionally assigned as interrupt number. > platform_get_irq(), as called from the smsc driver, gets this negative interrupt > number, and passes it unconditionally to irq_get_irq_data(), which returns NULL. > The NULL pointer is then passed to irqd_set_trigger_type() which, not entirely > surprisingly, crashes. > > So, in other words, lots of bugs here. Nevertheless, I would suggest to keep using > postcore_initcall(), at least until it is sure that all gpio clients handle -EPROBE_DEFER > correctly. I'm inviting Shawn and Uwe to the discussion. The proper fix in this particular case should be like this one: diff --git a/arch/arm/mach-imx/mach-kzm_arm11_01.c b/arch/arm/mach-imx/mach-kzm_arm11_01.c index 31df4361996f..8288acfe7221 100644 --- a/arch/arm/mach-imx/mach-kzm_arm11_01.c +++ b/arch/arm/mach-imx/mach-kzm_arm11_01.c @@ -245,13 +245,17 @@ static void __init kzm_board_init(void) mxc_iomux_setup_multiple_pins(kzm_pins, ARRAY_SIZE(kzm_pins), "kzm"); - kzm_init_ext_uart(); - kzm_init_smsc9118(); kzm_init_imx_uart(); pr_info("Clock input source is 26MHz\n"); } +static void __init kzm_late_init(void) +{ + kzm_init_ext_uart(); + kzm_init_smsc9118(); +} + /* * This structure defines static mappings for the kzm-arm11-01 board. */ @@ -291,5 +295,6 @@ MACHINE_START(KZM_ARM11_01, "Kyoto Microcomputer Co., Ltd. KZM-ARM11-01") .init_irq = mx31_init_irq, .init_time = kzm_timer_init, .init_machine = kzm_board_init, + .init_late = kzm_late_init, .restart = mxc_restart, MACHINE_END -- But I agree that there might be more legacy boards (i.MX31 only IMHO), which may attempt to manipulate GPIO lines before subsys_initcall() level. Would it be better to move i.MX31 IOMUX controller driver under pinctrl roof? Any suggestions are welcome. -- With best wishes, Vladimir