Re: [PATCH RFC 2/2] gpiolib: check the 'ngpios' property in core gpiolib code

[Andy Shevchenko]

On Thu, Nov 11, 2021 at 10:26 PM Bartosz Golaszewski <brgl@xxxxxxxx> wrote:
>
> Several drivers read the 'ngpios' device property on their own, but
> since it's defined as a standard GPIO property in the device tree bindings
> anyway, it's a good candidate for generalization. If the driver didn't
> set its gc->ngpio, try to read the 'ngpios' property from the GPIO
> device's firmware node before bailing out.

Thanks!

...

> +               ret = fwnode_property_read_u32(gdev->dev.fwnode, "ngpios",
> +                                              &ngpios);

I'm wondering if there is any obstacle to call

               ret = device_property_read_u32(&gdev->dev, "ngpios", &ngpios);

?

Rationale (the main one) is to avoid direct dereference of fwnode from
struct device (it might be changed in the future). I really prefer API
calls here.

> +               if (ret == 0) {
> +                       gc->ngpio = ngpios;
> +               } else {
> +                       chip_err(gc, "tried to insert a GPIO chip with zero lines\n");
> +                       ret = -EINVAL;
> +                       goto err_free_descs;
> +               }

I would prefer the other way around and without 'else' being involved.

>         }


-- 
With Best Regards,
Andy Shevchenko