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Message-ID: <CAFSsGVuCZwk4PY9SCR_f=LiG920ZD3Hk-hxVNc9vHXMACtG7sA@mail.gmail.com>
Date: Wed, 21 Oct 2015 11:13:33 +0200
From: Heiner Kallweit <hkallweit1@...il.com>
To: Guenter Roeck <linux@...ck-us.net>
Cc: Linus Walleij <linus.walleij@...aro.org>,
Alexandre Courbot <gnurou@...il.com>,
linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH -next] gpio: generic: Revert to old error handling in bgpio_map
On Wed, Oct 21, 2015 at 9:12 AM, Guenter Roeck <linux@...ck-us.net> 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 <hkallweit1@...il.com>
> Signed-off-by: Guenter Roeck <linux@...ck-us.net>
> ---
> 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
>
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