Re: [PATCH RESEND v2] rust: regulator: add a bare minimum regulator abstraction

[Sebastian Reichel]

Hi,

On Wed, Mar 26, 2025 at 03:39:33PM -0300, Daniel Almeida wrote:
> +    pub fn get(dev: &Device, name: &CStr) -> Result<Self> {
> +        // SAFETY: It is safe to call `regulator_get()`, on a device pointer
> +        // received from the C code.
> +        let inner = from_err_ptr(unsafe { bindings::regulator_get(dev.as_raw(), name.as_ptr()) })?;
> +
> +        // SAFETY: We can safely trust `inner` to be a pointer to a valid
> +        // regulator if `ERR_PTR` was not returned.
> +        let inner = unsafe { NonNull::new_unchecked(inner) };
> +
> +        Ok(Self { inner })
> +    }

I think it's worth discussing using regulator_get() VS
regulator_get_optional(). We somehow ended up with the C regulator
API being more or less orthogonal to other in-kernel C APIs (clocks,
gpio, reset, LED) with the _optional suffixed version returning
-ENODEV for a missing regulator (and thus needing explicit handling)
and the normal version creating a dummy regulator (and a warning).

Considering the Rust API is new, it would be possible to let the
Rust get() function call regulator_get_optional() instead and then
introduce something like get_or_dummy() to call the normal
regulator_get() C function.

I see reasons in favor and against this. I just want to make sure it
has been considered before the API is being used, which makes it a
lot harder to change.

Greetings,

-- Sebastian

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