From mboxrd@z Thu Jan 1 00:00:00 1970 From: Heiner Kallweit Subject: Re: [PATCH -next] gpio: generic: Revert to old error handling in bgpio_map Date: Wed, 21 Oct 2015 11:13:33 +0200 Message-ID: References: <1445411520-7175-1-git-send-email-linux@roeck-us.net> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Return-path: Received: from mail-wi0-f169.google.com ([209.85.212.169]:36740 "EHLO mail-wi0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750895AbbJUJNf (ORCPT ); Wed, 21 Oct 2015 05:13:35 -0400 In-Reply-To: <1445411520-7175-1-git-send-email-linux@roeck-us.net> Sender: linux-gpio-owner@vger.kernel.org List-Id: linux-gpio@vger.kernel.org To: Guenter Roeck Cc: Linus Walleij , Alexandre Courbot , linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org On Wed, Oct 21, 2015 at 9:12 AM, Guenter Roeck wrote: > Returning an error instead of NULL in bgpio_map if > platform_get_resource_byname does not find a resource was introduced with > commit cf3f2a2c8bae ("gpio: generic: improve error handling in bgpio_map"). > This results in several qemu runtime failures with default and non-default > configurations, if attempts are made to boot from mmcblk0. Examples for > failures with multi_v7_defconfig are > > Machine: vexpress-a9 dtb: vexpress-v2p-ca9 > Machine: vexpress-a15 dtb: vexpress-v2p-ca15-tc1 > > Crash: > > VFS: Cannot open root device "mmcblk0" or unknown-block(0,0): error -6 > Please append a correct "root=" boot option; here are the available partitions: > Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0) > > Looking into the code, always returning an error if bgpio_map fails > does not appear to make much sense, since the code in bgpio_setup_io > specifically supports some of the resources to be NULL. > Indeed. Seems like "dat" is the only mandatory resource. Previously there was a double check that "dat" is set: in bgpio_dev_probe and in bgpio_setup_io With your proposed patch the check in bgpio_dev_probe is removed. Due to the (previously redundant) check in bgpio_setup_io it's ok however. One could only discuss whether "dat" should be checked as early as possible (in bgpio_dev_probe instead of bgpio_setup_io). But that's something I'd consider to be more or less cosmetic. > Fixes: cf3f2a2c8bae ("gpio: generic: improve error handling in bgpio_map") > Cc: Heiner Kallweit > Signed-off-by: Guenter Roeck > --- > drivers/gpio/gpio-generic.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpio/gpio-generic.c b/drivers/gpio/gpio-generic.c > index d8b1700b9519..bd5193c67a9c 100644 > --- a/drivers/gpio/gpio-generic.c > +++ b/drivers/gpio/gpio-generic.c > @@ -586,7 +586,7 @@ static void __iomem *bgpio_map(struct platform_device *pdev, > > r = platform_get_resource_byname(pdev, IORESOURCE_MEM, name); > if (!r) > - return IOMEM_ERR_PTR(-EINVAL); > + return NULL; > > sz = resource_size(r); > if (sz != sane_sz) > -- > 2.1.4 >