Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752879AbaLBKc1 (ORCPT ); Tue, 2 Dec 2014 05:32:27 -0500 Received: from mail-la0-f53.google.com ([209.85.215.53]:65397 "EHLO mail-la0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751371AbaLBKcW (ORCPT ); Tue, 2 Dec 2014 05:32:22 -0500 MIME-Version: 1.0 In-Reply-To: References: <1416383487-15993-1-git-send-email-acourbot@nvidia.com> Date: Tue, 2 Dec 2014 11:32:20 +0100 X-Google-Sender-Auth: BMMjYRwdiHJh-b9hQtn8zco2-c0 Message-ID: Subject: Re: [PATCH] gpio: remove gpio_descs global array From: Geert Uytterhoeven To: Linus Walleij , Alexandre Courbot Cc: "linux-gpio@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Alexandre Courbot , Linux-sh list Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Linus, Alexandre, On Fri, Nov 28, 2014 at 11:29 AM, Linus Walleij wrote: > On Wed, Nov 19, 2014 at 8:51 AM, Alexandre Courbot wrote: >> Replace the ARCH_NR_GPIOS-sized static array of GPIO descriptors by >> dynamically-allocated arrays for each GPIO chip. >> >> This change makes gpio_to_desc() perform in O(n) (where n is the number >> of GPIO chips registered) instead of O(1), however since n is rarely >> bigger than 1 or 2 no noticeable performance issue is expected. >> Besides this provides more incentive for GPIO consumers to move to the >> gpiod interface. One could use a O(log(n)) structure to link the GPIO >> chips together, but considering the low limit of n the hypothetical >> performance benefit is probably not worth the added complexity. >> >> This patch uses kcalloc() in gpiochip_add(), which removes the ability >> to add a chip before kcalloc() can operate. I am not aware of such >> cases, but if someone bisects up to this patch then I will be proven >> wrong... >> >> Signed-off-by: Alexandre Courbot > > OK patch applied. Let's see if the world explodes. This patch changes a return value from -EPROBE_DEFER to -EINVAL in regulator-gpio when a GPIO cannot be found yet, causing probe failures on r8a7791/koelsch: of_get_named_gpiod_flags: can't parse 'enable-gpio' property of node '/regulator@1[0]' of_get_named_gpiod_flags: parsed 'gpios' property of node '/regulator@1[0]' - status (-517) -gpio-0 (?): gpiod_request: status -517 -gpio-regulator regulator@1: Could not obtain regulator setting GPIOs: -517 -platform regulator@1: Driver gpio-regulator requests probe deferral +------------[ cut here ]------------ +WARNING: CPU: 0 PID: 1 at /scratch/geert/linux/linux-renesas/drivers/gpio/gpiolib.c:80 gpio_to_desc+0x94/0xac() +invalid GPIO 0 +Modules linked in: +CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.18.0-rc7-koelsch-05803-ge7a5d822abfc727e #634 +Hardware name: Generic R8A7791 (Flattened Device Tree) +Backtrace: +[] (dump_backtrace) from [] (show_stack+0x18/0x1c) + r6:c04608f7 r5:00000009 r4:00000000 r3:00200040 +[] (show_stack) from [] (dump_stack+0x78/0x94) +[] (dump_stack) from [] (warn_slowpath_common+0x70/0x94) + r4:eec53d10 r3:c04f3390 +[] (warn_slowpath_common) from [] (warn_slowpath_fmt+0x38/0x40) + r8:eed4a600 r7:00000001 r6:00000000 r5:00000000 r4:c04f9430 +[] (warn_slowpath_fmt) from [] (gpio_to_desc+0x94/0xac) + r3:00000000 r2:c0460931 +[] (gpio_to_desc) from [] (gpio_request_one+0x18/0xc4) + r5:00000000 r4:00000000 +[] (gpio_request_one) from [] (gpio_request_array+0x28/0x60) + r6:00000004 r5:00000000 r4:eed5a4c0 r3:00000002 +[] (gpio_request_array) from [] (gpio_regulator_probe+0x424/0x5a4) + r7:eed4a610 r6:00000004 r5:eed464d0 r4:eed5a5d0 +[] (gpio_regulator_probe) from [] (platform_drv_probe+0x50/0xa0) + r10:00000000 r9:c0509f80 r8:c04fa648 r7:00000000 r6:c04fa648 r5:eed4a610 + r4:ffffffed +[] (platform_drv_probe) from [] (driver_probe_device+0xc0/0x204) + r6:00000000 r5:c054ae0c r4:eed4a610 r3:c022a7cc +[] (driver_probe_device) from [] (__driver_attach+0x70/0x94) + r8:c04ee560 r7:c04fe4b0 r6:c04fa648 r5:eed4a644 r4:eed4a610 r3:00000000 +[] (__driver_attach) from [] (bus_for_each_dev+0x74/0x98) + r6:c0229190 r5:c04fa648 r4:00000000 r3:00000001 +[] (bus_for_each_dev) from [] (driver_attach+0x20/0x28) + r6:eed52300 r5:00000000 r4:c04fa648 +[] (driver_attach) from [] (bus_add_driver+0xe8/0x1d0) +[] (bus_add_driver) from [] (driver_register+0xa4/0xe8) + r7:c04ee560 r6:00000000 r5:c04c0498 r4:c04fa648 +[] (driver_register) from [] (__platform_driver_register+0x50/0x64) + r5:c04c0498 r4:eed5a800 +[] (__platform_driver_register) from [] (gpio_regulator_init+0x18/0x20) +[] (gpio_regulator_init) from [] (do_one_initcall+0x108/0x1b8) +[] (do_one_initcall) from [] (kernel_init_freeable+0x11c/0x1e4) + r9:c0509f80 r8:c0509f80 r7:c04dfcf0 r6:c04d7c2c r5:0000006d r4:00000004 +[] (kernel_init_freeable) from [] (kernel_init+0x10/0xec) + r9:00000000 r8:00000000 r7:00000000 r6:00000000 r5:c0384528 r4:00000000 +[] (kernel_init) from [] (ret_from_fork+0x14/0x3c) + r4:00000000 r3:eec52000 +---[ end trace e95579bdd1fdbe74 ]--- +gpiod_request: invalid GPIO +gpio-regulator regulator@1: Could not obtain regulator setting GPIOs: -22 +gpio-regulator: probe of regulator@1 failed with error -22 Reverting commit 14e85c0e69d5c7fdbd963edbbec1dc5cdd385200 ("gpio: remove gpio_descs global array") fixes the issue. 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/