linux-kernel - Re: [PATCH] gpio: brcmstb: support gpio-line-names property

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Date:   Mon, 9 Mar 2020 00:45:02 -0700
From:   Gregory Fong <gregory.0xf0@...il.com>
To:     Doug Berger <opendmb@...il.com>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        bcm-kernel-feedback-list <bcm-kernel-feedback-list@...adcom.com>,
        linux-gpio@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] gpio: brcmstb: support gpio-line-names property

Hi Doug,

On Fri, Mar 6, 2020 at 4:14 PM Doug Berger <opendmb@...il.com> wrote:
>
> The default handling of the gpio-line-names property by the
> gpiolib-of implementation does not work with the multiple
> gpiochip banks per device structure used by the gpio-brcmstb
> driver.
>
> This commit adds driver level support for the device tree
> property so that GPIO lines can be assigned friendly names.
>
> Signed-off-by: Doug Berger <opendmb@...il.com>

I've added a few comments below.  With the suggested updates:
Acked-by: Gregory Fong <gregory.0xf0@...il.com>

> ---
>  drivers/gpio/gpio-brcmstb.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 44 insertions(+)
>
> diff --git a/drivers/gpio/gpio-brcmstb.c b/drivers/gpio/gpio-brcmstb.c
> index 05e3f99ae59c..e9ab246e2d42 100644
> --- a/drivers/gpio/gpio-brcmstb.c
> +++ b/drivers/gpio/gpio-brcmstb.c
> @@ -603,6 +603,49 @@ static const struct dev_pm_ops brcmstb_gpio_pm_ops = {
>         .resume_noirq = brcmstb_gpio_resume,
>  };
>
> +static void brcmstb_gpio_set_names(struct device *dev,
> +                                  struct brcmstb_gpio_bank *bank)
> +{
> +       struct device_node *np = dev->of_node;
> +       const char **names;
> +       int nstrings, base;
> +       unsigned int i;
> +
> +       base = bank->id * MAX_GPIO_PER_BANK;
> +
> +       nstrings = of_property_count_strings(np, "gpio-line-names");
> +       if (nstrings <= base)
> +               /* Line names not present */
> +               return;
> +
> +       names = devm_kcalloc(dev, MAX_GPIO_PER_BANK, sizeof(char *),

Please use sizeof(*names) instead of sizeof(char *).

> +                            GFP_KERNEL);
> +       if (!names)
> +               return;
> +
> +       /*
> +        * Make sure to not index beyond the end of the number of descriptors
> +        * of the GPIO device.
> +        */
> +       for (i = 0; i < bank->width; i++) {
> +               const char *name;
> +               int ret;
> +
> +               ret = of_property_read_string_index(np, "gpio-line-names",
> +                                                   base + i, &name);
> +               if (ret) {
> +                       if (ret != -ENODATA)
> +                               dev_err(dev, "unable to name line %d: %d\n",
> +                                       i, ret);

Recommend adding the GPIO bank ID to this error message.

Best regards,
Gregory