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

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Message-ID: <CACRpkdZ1p3_U_yth-rCEKdPsuFNFnxsE3kTeP7krf-xHuSGkFw@mail.gmail.com>
Date:   Wed, 11 Mar 2020 16:32:29 +0100
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Doug Berger <opendmb@...il.com>
Cc:     Gregory Fong <gregory.0xf0@...il.com>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        bcm-kernel-feedback-list <bcm-kernel-feedback-list@...adcom.com>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH V2] gpio: brcmstb: support gpio-line-names property

On Mon, Mar 9, 2020 at 8:02 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>
> +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