Re: [PATCH V2] gpio: brcmstb: support gpio-line-names property

[Linus Walleij]

On Mon, Mar 9, 2020 at 8:02 PM Doug Berger <opendmb@xxxxxxxxx> 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@xxxxxxxxx>
> +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;

I don't understand why that thing is named "base".

> +       unsigned int i;
> +
> +       base = bank->id * MAX_GPIO_PER_BANK;

That would be ngpios or something.

But you alread have what you need in bank->gc.ngpio, right?

So why calculate it?

> +       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(*names),
> +                            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",
> +                                       base + i, ret);
> +                       break;
> +               }
> +               if (*name)
> +                       names[i] = name;
> +       }
> +
> +       bank->gc.names = names;
> +}

Why can't you just make the function
devprop_gpiochip_set_names() public, (line in <linux/gpio/driver.h>)
and convert your np to a fwnode and call that &bank->gc ?

Yours,
Linus Walleij