linux-kernel - Re: [PATCH 1/1] gpio: Fix ngpio in gpio-xilinx driver

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Date:	Tue, 23 Sep 2014 17:38:51 +0200
From:	Linus Walleij <linus.walleij@...aro.org>
To:	Gernot Vormayr <gvormayr@...il.com>
Cc:	Alexandre Courbot <gnurou@...il.com>,
	Michal Simek <michal.simek@...inx.com>,
	"linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/1] gpio: Fix ngpio in gpio-xilinx driver

On Thu, Sep 18, 2014 at 11:03 AM, Gernot Vormayr <gvormayr@...il.com> wrote:

> If one adds 'gpio-controller;' to the chip in the devicetree, then
> initialization fails with 'gpiochip_find_base: cannot find free range',
> because ngpio is 0. This patch fixes the bug.
>
> Tested on ml507 board.
>
> Signed-off-by: Gernot Vormayr <gvormayr@...il.com>
> ---
>  drivers/gpio/gpio-xilinx.c | 11 +++++++----
>  1 file changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpio/gpio-xilinx.c b/drivers/gpio/gpio-xilinx.c
> index 1248186..4606ad2 100644
> --- a/drivers/gpio/gpio-xilinx.c
> +++ b/drivers/gpio/gpio-xilinx.c
> @@ -197,6 +197,7 @@ static int xgpio_of_probe(struct device_node *np)
>         struct xgpio_instance *chip;
>         int status = 0;
>         const u32 *tree_info;
> +       u32 ngpio;
>
>         chip = kzalloc(sizeof(*chip), GFP_KERNEL);
>         if (!chip)
> @@ -215,8 +216,9 @@ static int xgpio_of_probe(struct device_node *np)
>         chip->mmchip.gc.ngpio = 32;

Delete that line ^

>
>         /* Check device node and parent device node for device width */
> -       of_property_read_u32(np, "xlnx,gpio-width",
> -                             (u32 *)&chip->mmchip.gc.ngpio);
> +       status = of_property_read_u32(np, "xlnx,gpio-width", &ngpio);
> +       if (status == 0)
> +               chip->mmchip.gc.ngpio = (u16)ngpio;

Rewrite like this:

if (of_property_read_u32(np, "xlnx,gpio-width", &ngpio))
    ngpio = 32;
chip->mmchip.gc.ngpio = (u16)ngpio;

>
>         spin_lock_init(&chip->gpio_lock);
>
> @@ -262,8 +264,9 @@ static int xgpio_of_probe(struct device_node *np)
>                 chip->mmchip.gc.ngpio = 32;
>
>                 /* Check device node and parent device node for device width */
> -               of_property_read_u32(np, "xlnx,gpio2-width",
> -                                    (u32 *)&chip->mmchip.gc.ngpio);
> +               status = of_property_read_u32(np, "xlnx,gpio2-width", &ngpio);
> +               if (status == 0)
> +                       chip->mmchip.gc.ngpio = (u16)ngpio;

Same comment.

The fact that the same code appears in two places tells us something
is not quite right. Can you look into consolidating this (in a separate
patch)?

Yours,
Linus Walleij
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