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Date: Wed, 14 May 2025 11:37:46 +0200
Message-Id: <D9VS6WE94O04.GXFI0K5BH4XN@kernel.org>
Cc: "Daniel Almeida" <daniel.almeida@collabora.com>, "Miguel Ojeda"
 <ojeda@kernel.org>, "Alex Gaynor" <alex.gaynor@gmail.com>, "Boqun Feng"
 <boqun.feng@gmail.com>, "Gary Guo" <gary@garyguo.net>,
 =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= <bjorn3_gh@protonmail.com>, "Benno Lossin"
 <benno.lossin@proton.me>, "Andreas Hindborg" <a.hindborg@kernel.org>,
 "Alice Ryhl" <aliceryhl@google.com>, "Trevor Gross" <tmgross@umich.edu>,
 "Danilo Krummrich" <dakr@kernel.org>, "Boris Brezillon"
 <boris.brezillon@collabora.com>, "Sebastian Reichel"
 <sebastian.reichel@collabora.com>, "Liam Girdwood" <lgirdwood@gmail.com>,
 <linux-kernel@vger.kernel.org>, <rust-for-linux@vger.kernel.org>
Subject: Re: [PATCH v3] rust: regulator: add a bare minimum regulator
 abstraction
From: "Benno Lossin" <lossin@kernel.org>
To: "Mark Brown" <broonie@kernel.org>
X-Mailer: aerc 0.20.1
References: <20250513-topics-tyr-regulator-v3-1-4cc2704dfec6@collabora.com>
 <D9VATLUHDGU8.53I80TGVRV0J@kernel.org>
 <aCRKR5h_X04OXgjq@finisterre.sirena.org.uk>
In-Reply-To: <aCRKR5h_X04OXgjq@finisterre.sirena.org.uk>

On Wed May 14, 2025 at 9:46 AM CEST, Mark Brown wrote:
> On Tue, May 13, 2025 at 10:01:05PM +0200, Benno Lossin wrote:
>> On Tue May 13, 2025 at 5:44 PM CEST, Daniel Almeida wrote:
>
>> > +/// A [`Regulator`] that is known to be enabled.
>> > +///
>> > +/// # Invariants
>> > +///
>> > +/// - [`EnabledRegulator`] is a valid regulator that has been enabled=
.
>
>> This isn't fully clear what it's supposed to mean to me. Maybe mention
>> the `regulator_enable` function?
>
> I suspect this is adequately clear to someone with the domain specific
> knowledge required to be using the API.

I still think it's useful to name the exact function that is meant by
"enabled".

>> > +impl EnabledRegulator {
>> > +    fn as_ptr(&self) -> *mut bindings::regulator {
>> > +        self.inner.inner.as_ptr()
>> > +    }
>
>> > +    /// Disables the regulator.
>> > +    pub fn disable(self) -> Result<Regulator> {
>> > +        // Keep the count on `regulator_get()`.
>> > +        let regulator =3D ManuallyDrop::new(self);
>
>> Why don't we drop the refcount if the `regulator_disable` call fails?
>
> If you fail to disable the regulator then the underlying C code won't
> drop it's reference count.

So if it fails, the regulator should stay alive indefinitely? Would be
useful to explain that in the comment above the `ManuallyDrop`.

---
Cheers,
Benno