Re: [PATCH V4 04/10] dt-bindings: timestamp: Add nvidia,gpio-controller

[Linus Walleij]

On Thu, Mar 23, 2023 at 2:29 AM Dipen Patel <dipenp@xxxxxxxxxx> wrote:

> Introducing nvidia,gpio-controller property from Tegra234 SoCs onwards.
> This is done to help below case.
>
> Without this property code would look like:
> if (of_device_is_compatible(dev->of_node, "nvidia,tegra194-gte-aon"))
>         hte_dev->c = gpiochip_find("tegra194-gpio-aon",
>                                    tegra_get_gpiochip_from_name);
> else if (of_device_is_compatible(dev->of_node, "nvidia,tegra234-gte-aon"))
>         hte_dev->c = gpiochip_find("tegra234-gpio-aon",
>                                    tegra_get_gpiochip_from_name);
> else
>         return -ENODEV;
>
> This means for every future addition of the compatible string, if else
> condition statements have to be expanded.
>
> With the property:
> gpio_ctrl = of_parse_phandle(dev->of_node, "nvidia,gpio-controller", 0);
> ....
> hte_dev->c = gpiochip_find(gpio_ctrl, tegra_get_gpiochip_from_of_node);
>
> This simplifies the code significantly. The introdunction of this
> property/binding does not break existing Tegra194 provider driver.
>
> Signed-off-by: Dipen Patel <dipenp@xxxxxxxxxx>

It is fair to assume that other operating systems will need this too
so I interpret the commit message as an example of the issues
faced by anyone making a driver for this HW.
Reviewed-by: Linus Walleij <linus.walleij@xxxxxxxxxx>

Yours,
Linus Walleij